Mercury Service Manual

SERVICE MANUAL Mercury 2 Cyl.

MERCURYMercury Marine

Div. Brunswick Corp.Fond du Lac, Wisconsin 54935

TWO-CYLINDER MODELSYear Produced Model1970-1971 40019724978 4021978-1983 401984-1985 35

CONDENSED SERVICE DATA

TUNE-UPHp/rpm:

Model 35 35/5400-6000Models 40, 400 & 402 40/5000-5500

Bore 2.870 in.(72.9 mm)

Stroke 2.562 in.(65.1mm)

Displacement 33.3 cu. in.(546 cc)

Compression At Cranking Speed *Spark Plug:

AC V40FFMtChampion L76V

Electrode Gap Surface GapIgnition:

Type Solid StateTrigger Gap (Model 400) 0.050-0.060 in.

(1.27-1.52 mm)Carburetor Pickup Timing See TextMaximum Advance See Text

FuekOil Ratio See Text

*Not more than 15 psi (103.5 kPa) variations betweencylinders,

TAC type M40FFX spark plugs gapped at 0.030 inch (0.76mm) are recommended for use on 1971 400 models if roughlow speed operation is noted.

SIZES-CLEARANCESPiston Rings:

End Gap *Side Clearance *

Piston Skirt Clearance *

SIZES-CLEARANCES CONT.Crankshaft Bearings:

Top Main Bearing Roller or Ball BearingCenter Main Bearing Bushing With Reed ValveLower Main Bearing Ball BearingCrankpin Caged Rollers

Piston Pin Bearing In Rod Loose RollersNumber of Rollers Per Rod 29

* Publication not authorized by manufacturer.

TIGHTENING TORQUESConnecting Rod 180 in.-lbs.

(20.3 N-m)Crankcase Screws 200 in.-lbs.

(22.6 N-m)Cylinder Cover:

35 HP 100 in.-lbs.(11.3 N-m)

40 HP 70 in.-lbs.(7.9 N-m)

Exhaust Cover 200 in.-lbs.(22.6 N-m)

Flywheel Nut 70-75 ft.-lbs.(95.2-102 N-m)

Reed Screws 25 in.-lbs.(2.8 N-m)

Spark Plugs 240 in.-lbs.(27.1 N-m)

Transfer Port Cover:35 HP 50 in.-lbs.

(5.6 N-m)40 HP 60 in.-lbs.

(6.8 N-m)

Illustrations courtesy Mercury 225

Mercury 2 Cyl. OUTBOARD MOTOR

LUBRICATION

The engine is lubricated by oil mixedwith the fuel. Fuel should be regularleaded, low lead or unleaded gasolinewith a minimum pump octane rating of86. Premium gasoline may be used ifdesired regular gasoline is not available.Recommended oil is Quicksilver Formu-la 50 or 50-D. A good quality NMMA cer-

Fig, M1O-1-Exptod0d vi0w of M0rcarb "WMK"C0rbur0tor. Tlllotson carbur0tor is similar.

1. Body2. Bowl cover 14. Throttle shaft3. Inlet fitting 15. Welch plug4. Gasket 16. Idle mixture screw5. Inlet needle & seat 17. Spring6. Primary lever 18. Plug7. Pin 19. Venturi8. Secondary lever 20. Main jet9. Float 21. Gasket

10. Gasket 22. Plug11. Follower 23. Main nozzle12. Idle tube 24. Plug13. Plug 25. Spring

Fig, M1O-2-Dlstanc0 (A) should b0 1^2 Inch(10.32 mm), R0f0r to text for adiu8tm0nt pro-C0dur0 and Fig, MIO-I for parts ld0ntiflcatlon.

tified TC-Wn oil may be used. Fuel:oilratio should be 50:1 when using Formula50 or 50-D oil. Follow fuel:oil ratio rec-ommended by oil manufacturer if For-mula 50 or 50-D is not used.

Tb break in new or overhauled motors,observe the following: Vary throttleopening during first hour of operationwhile avoiding extended idling in coldwater and prolonged full throttle op-eration.

The lower unit gears and bearings arelubricated by oil contained in the gear-case. Only Quicksilver Super Duty GearLubricant should be used. Gearcase isfilled through the lower plug hole onport side of case, with motor in an up-right position. The vent plug (located aftand above the fill plug) should be re-moved when filling. Lubricant should bemaintained at level of vent plug.

FUEL SYSTEM

CARBURETOR. Standard make ofcarburetor is a Tillotson KD-5A on Mod-el 400 prior to serial number 2979679.Standard make of carburetor on all oth-er models is a MerCarb WMK. Standardmain jet (20—Fig. MlO-1) size on earlymodels is 0.0785 inch (2 mm) and 0.072inch (1.83 mm) on later models (afterserial number 5823917). Various main jet(20) sizes are available for adjusting thecalibration for elevations or other spe-cial conditions. Preliminary adjustmentof idle mixture screw (16) is 1 to IV4turns out from a lightly seated position.Recommended idle speed is 650-750rpm on early models and 500-650 onlater models. Ac^ust idle speed with en-gine running at normal operating tem-perature in forward gear.

With the outboard motor properlymounted on a boat or suitable tank, im-merse the lower unit. Connect atachometer and set it on the appropri-ate range scale. Start the engine and al-low it to warm up to normal operatingtemperature. With the engine runningat idle speed and forward gear engaged,turn idle mixture screw (16) untilsmooth engine operation is noted. Read-just engine idle speed screw (IS—Fig.MlO-8, Fig. MlO-13 or Fig. MlO-14) to rec-ommended idle speed if required.

1b determine float level, invert bowlcover (2—Fig. MlO-2) with inlet needleand seat (5), primary lever (6) andsecondary lever (8) installed. On earlymodels, measure distance (A) from car-buretor body surface to top of secon-dary lever (8). Distance (A) should be*V32 inch (10.3 mm). Adjust distance (A)by bending curved end of primary lever(6). On later models (after serial num-ber 5823917) bend curved end of pri-mary lever (6) so secondary lever (8) isparallel to bowl cover (2) mating surface.

Tb check float drop, position bowl cov-er upright (Fig. MlO-3) and measure dis-tance (D) between primary lever (6) andend of secondary lever (8). Distance (D)should be V4 inch (6.4 mm). Bend tab (T)to adjust. The contact spring located incenter of float (9-Fig. MlO-1) should ex-tend V32 inch (2.4 mm) above top offloat. Inspect spring and renew ifstretching or other damage is noted.

SPEED CONTROL LINKAGE. Thespeed controls change ignition timingand the amount of carburetor throttleopening. The timing and throttle open-ing must be correctly synchronized toprovide proper operation. When check-ing, the complete system should betested in sequence to ensure desired re-sults. Speed control linkage used on 400models is different from linkage used on35, 40 and 402 models. Refer to the ap-propriate following paragraphs.

Model 400

Before attempting any test, check alllinkage for free movement. Make cer-tain that spark advance arm (Fig. MIO-5) remains aligned with the throttle armthroughout its full movement, from idleuntil the spark control arm contacts the

Fig. M10 3-With bowl co¥0r (2) upright,distanc0 (D) b0tw00n primary l0V0r ($) and end ofsecondary t0¥0r (8) should b0 % Inch (6,4 mm),

B0nd tab (T) to adjust

Fig. M1O-5 — M0rc 400 spark ad¥Bnc0 arm andthrottle arm should be aiign0d BB shown fromtdl0 until the spark Bd¥anc0 arm contacts BiopBcrBw (IM). Th0 throttl0 arm should still ba BbiBto mo¥0 until CBrburBtor throttle is completely

open.

226 Illustrations courtesy Mercury


maximum advance stop screw. Thespark advance arm is attached to thethrottle arm with a spring which allowsfurther movement of the throttle armafter ignition reaches maximum ad-vance. Excessive friction in linkage, in-correct routing of pickup coil wires, etc.,may prevent free movement and resultin inaccurate checks and adjustments.

Check clearance between triggerpickup coil (C-Fig. MlO-6) and triggermagnets in flywheel. Trigger gap(clearance) should be 0.050-0.060 inch(1.27-1.52 mm). If incorrect, loosenscrews (S) and add or remove shims be-tween plate (P) and starter housing.Make certain that trigger gap remainswithin limits throughout operating slotlength. Screws (S) should be centered inelongated holes in plate (P).

Connect a suitable tachometer to theengine and a timing light to the topcylinder. Start the engine and shift intoforward gear. Increase engine speed un-til the two ignition timing dots (D-Fig.MlO-7) are in center of timing window.With controls set as outlined, theprimary pickup edge of throttle plateshould just contact throttle follower(11-Fig. MlO-8). If the primary pickupis not in contact with the follower or ifthe throttle is partially open, loosen thetwo screws that attach the throttle plateto the bottom of the actuator and movethe throttle plate. Repeat the above pro-cedure to confirm the proper adjust-ment.

Increase engine speed to 5000-5200rpm and check maximum advance tim-ing marks in window (W-Fig. MlO-7).If the straight line timing mark is not inthe center of the timing window, loosenlocknut and turn ignition maximum ad-vance stop screw (IM-Fig. MlO-5) tostop movement of the spark advancearm when maximum advance timing iscorrect.

With the engine stopped, move speedcontrols slowly from idle toward fastposition and stop just as the spark ad-vance arm contacts ignition maximumadvance stop screw (IM).

NOTE: It is important that maximum ad-vance is correct before attempting thischeck. Just as the spark advance armtouches stop screw (IM), the secondarythrottle pickup should just contact thesecondary arm of follower as shown inFig. IVI10-9. If the secondary pickup is notyet touching or if the primary arm is awayfrom cam at (X), carefully bend thesecondary pickup until correct. If correc-tions are necessary, recheck by againmoving speed controls from idle towardfast until spark advance arm just contactsstop screw (IM — Fig. Ml0-5).

Carefully move the speed controlstoward maximum speed position whilechecking for play at the carburetorthrottle follower. The throttle stopscrew (Fig. Ml0-10) should stop move-ment of throttle arm just before all playis removed from the throttle andfollower (11-Fig. MlO-9). With throttlearm against stop screw (Fig. MlO-10),throttle follower (11-Fig, MlO-9)should have approximately 0.010-0,015inch (0.25-0.38 mm) play to preventdamage. If speed controls are forcedafter throttle is completely open, thesecondary pickup may be bent or otherdamage may result.

Idle speed is adjusted at stop screw(IS-Fig. MlO-8). Refer to the CAR-BURETOR section for idle speed adjust-ment.

Fig. MtO-6- View of Modei 400 trigger coii (C) in-staiied. The coii moves in the siot to change igni-tion timing. Plate (P) should be centered In

screws ($).

Models 35, 40 And 402

To synchronize ignition timing andthrottle opening, proceed as follows:Connect a power timing light to the topcylinder spark plug lead and attach asuitable tachometer to the engine. Withthe engine running, shift into "Forward"gear. On manual start models, view win-dow (A-Fig. MlO-11) on all 35 and 40models and 402 models with serialnumber 4726798 and above, and window

Fig. M10 7-Vlew showing timing dots (D) andwindow (W) used on Model 400. Refer to text.

Fig. MlO-9-On Model 400, view of the throttlefotiower ( I t ; attached to top of carburetor throt-tie shaft. Refer to text for checking the secon-

dary throttie pickup.

Fig. MtO-iO-View of Modei 400 controi arms inmaximum speed position. The spark advancearm contacts the ignition maximum advancescrew before the throttie arm contacts the throt-tie stop screw (TS), Refer to text for adjustment

Fig. MIO'8-View showing throttie follower (1Uidle mixture screw (16) and idie speed screw (IS)

used on Modei 400.

Fig. M10-11 — On manuai start modeis, view win-dow (A) on aii 35 and 40 models and 402 modeiswith serial number 4726798 and above, and win-dow (B) on 402 modeis prior to seriai number

4726798.



(B) on 402 models prior to serial number4726798. On electric start models, referto timing pointer and numbered degreemarks on flywheel. Increase the enginespeed until the two ignition timing dots(D-Fig. Ml0-12), on manual startmodels, are aligned with timing windownotch (N). On electric start models, tim-ing pointer should align with 2°-5°BTDC timing mark on flywheel. At thispoint, on 402 models and early 40models, adjust turnbuckle (T-Fig.MlO-13) so throttle cam just contactsfollower (11) at point (P). On 35 modelsand late 40 models, adjust primarythrottle pickup screw (PP - Fig. MlO-14)so throttle cam just contacts follower(11-Fig. MlO-13) at point (P).

Increase engine speed to 5000-5500rpm on 40 models and 5400-6000 rpm on

Fig. M10-12- View showing timing dots (D), tim-ing window (IV) and notch (N) used on Modeis 35,

40 and 402 with manuai start. Refer to text.

Fig. M1013 - View of speed controi componentsused on 402 models and eBrly 40 models. Refer

to text,11. Throttle followerP. Contact point IS. Idle speed screwT. Turnbuckle PA. Secondary pickup arm

35 models and check maximum advancetiming at timing pointer on electric startmodels and look for mark in window(W-Fig. Ml0-12) on manual startmodels. If the straight line timing markis not aligned with notch (N) on manualstart models or 27° BTDC mark on elec-tric start models, loosen locknut andturn ignition maximum advance stopscrew (IM-Fig. MlO-4 or Fig. MlO-15)to stop movement of the spark advancearm (S) when maximum advance timingis correct. Tighten locknut on screw.

Stop the engine and remove the tim-ing light. Position spark advance arm (S)so it touches maximum advance stopscrew (IM). Adjust throttle pickup screw(TP-Fig. MlO-14 or Fig. MlO-16) so itjust contacts secondary pickup arm(PA-Fig. MlO-13) on carburetorfollower.

Move speed control to maximumspeed position and check carburetor tomake sure throttle valve is completelyopen. The throttle stop screw (TS-Fig.MlO-14 or Fig. MlO-15) should stopmovement of throttle arm just before allplay is removed from the throttle andfollower (11-Fig. MlO-13). With throt-tle arm against stop screw (TS-Fig.MlO-14 or Fig. MlO-15), throttlefollower (11-Fig. MlO-13) should haveapproximately 0.010-0.015 inch (0.25-0.38 mm) play to prevent damage.

Idle speed is adjusted at stop screw-(IS-Fig. MlO-13 or Fig. MlO-14). Referto the CARBURETOR section for idlespeed adjustment.

REED VALVES. The inlet reedvalves are located on the center mainbearing assembly. The crankshaft mustbe removed before reed valves can beserviced.

Reed petals (18-Fig. MlO-27) shouldbe perfectly flat and have no more than0.007 inch (0.18 mm) clearance betweenfree end and seating surface of mainbearing. The reed stop (17) must becarefully adjusted to provide 5/32 inch(3.97 mm) clearance between end of stopand reed seating surface. Seating sur-

Fig, MiO-U-View of speedcontroi components used on35 models and late 40

models. Refer to text.S. Spark advance arm

IM. Maximum advance stopscrew

IS. Idle speed screwPP. Primaiy throttle pickup

screwTP. Secondary throttle pickup

screwTS. Throttle stop screw

face on bearing must be smooth and flat,and may be refinished on a lapping plateafter removing reed valves. Do not at-tempt to bend or straighten a reed petaland never install a bent petal. Reeds andreed plates are secured by either shortscrews threaded into main bearing or byscrews extending through the bearingand having nuts on the ends. Lubricatereed valve before assembly. On modelsso equipped, install screws (21) withheads toward top and nuts (16) towardbottom to provide proper clearance forcrankshaft.

FUEL PUMP. A diaphragm type fuelpump is used. Pressure and vacuumpulsations from the crankcase alternateto pull fuel from supply tank and flII car-buretor float bowl. Most of the work isperformed by the main supply chamber(5-Fig. MlO-18). Vacuum in the crank-case pulls diaphragm (2) downwardcausing fuel to be drawn through inletline (8), past inlet check valve (7) intomain pump chamber (5). The alternatepressure forces diaphragm out and fuelleaves the chamber through outlet checkvalve (6). The booster pump chamber (3)

Fig. M1015-View identifying spark advancearm (S)^ maximum advance stop screw (iM) andthrottie stop screw (TS) used on 402 modeis and

eariy 40 modeis. Refer to text.

Fig. M10-16~View identifying secondary throt-tle pickup screw (TP) used on 402 modeis andeariy 40 modeis. Refer to text for adjustment pro-

cedures.



serves to dampen the action of the larg-er, main pump chamber (5), and in-crease maximum potential fuel flow.

When overhauling fuel pump, renewall defective or questionable compo-nents. On pump equipped with one redand one white color check valve, be surered color check valve is installed on in-take side of pump.

IGNITION SYSTEM

Early Models

Refer to Fig. MlO-20 for wiring dia-gram on Model 400 and Fig. MlO-21 forwiring diagram on Model 402 and earlyModel 40. All models are equipped withThunderbolt breakerless ignition. Referto the appropriate SPEED CONTROLLINKAGE section for checking and ad-justing ignition timing and speed controllinkage.

Check all wires and connections be-fore trouble-shooting ignition system.Make sure all connections are clean andtight.

Test ignition components using asuitable ohmmeter. The followingspecifications will aid trouble-shooting:

Model 400STATORManual Start—Blue lead and

ground 2100-2500 ohmsElectric Start—White lead and

ground 115-130 ohms

IGNITION COILPart A-332-4075A1

Primary—Positive terminal andground 0 ohms

Secondary—High tension tower andground 2400-3000 ohms

Part A-336-4592A2Primary—Positive terminal and

ground 0.01-0.015 ohmSecondary—High tension tower and

ground 9000-10500 ohms

TRIGGERPart A-332-4315A1

Brown and black leads . 27-41 ohmsPart A-332-4608A2 .No resistance testpossible

Model 402 (1972-1974)STATOR

Manual Start—Red and blueleads 5000-6400 ohms

Electric Start—Red lead andground 45-60 ohms

IGNITION COILPrimary—Positive and negative

terminals 0.02-0.04 ohmSecondary—High tension tower and


TRIGGERWhite and brown

leads 700-1000 ohms

Model 402 (1975-1978)STATOR

Blue lead andground 5000-6000 ohms

Red lead and ground . . . 50-60 ohms

IGNITION COILPrimary— Positive and negative

terminals 0.02-0,4 ohmSecondary—High tension tower and


TRIGGERBetween trigger

leads 800-1000 ohms

Models 35 and 40 Hp

IGNITION. An alternator driven ca-pacitor discharge ignition (CDI) systemis used. Ignition system consists of theflywheel, stator, trigger assembly,switch box and ignition coils. The sta-tor is mounted below the flywheel andincludes two capacitor charging coils.The trigger assembly consists of twotrigger coils and is mounted below theflywheel. Ignition timing is advancedand retarded by rotating trigger assem-bly in relation to the inner flywheelmagnets. Refer to SPEED CONTROLLINKAGE section for timing adjustmentprocedures. Diodes, capacitors andSCR's are contained in the switch box.Switch box, trigger assembly and statormust be serviced as unit assemblies. Re-

fer to Fig. MlO-21 for wiring diagram onearly model 40 and Fig. MlO-22 for 35hp and late 40 models.

If engine malfunction is noted, andthe ignition system is suspected, makesure the spark plugs and all electricalwiring are in acceptable condition andall electrical connections are clean andtight prior to trouble-shooting CDIsystem.

Proper testing of the switch box andignition coils requires the use of Quick-silver Multi-Meter DVA Tfester part 91-99750, or a suitable voltmeter capableof measuring a minimum of 400 DC volts

5 7 8-Fig. M10 18-Schematic view of diaphragm typefuei pump. Pump body mounts on side ofcyiinder block and is ported to two crankcases

as shown.1. Pressure ports 5. Main fuel chamber2. Diaphram 6. Outlet check valve3 Booster chamber 7. Inlet check valve4. To carburetor 8. Fuel inlet

1 ^EHCmf HARNESft

Fig, fyiW-20- Wiring diagram of eiectric starting 400 modeis. Ignition is similar on manual start 400modeis.



used with Quicksilver Direct VoltageAdaptor (DVA) part 91-89045. Follow in-structions provided by tester manufac-turer when performing tests. If thesetesters are not available, a process ofelimination must be used when testingthe ignition system. Stator and triggerassemblies can be effectively tested us-ing a suitable ohmmeter.

NOTE: All tests that involve cranking orrunning the engine must be performed withlead wires connected. Switch box case

iVIUST be grounded to engine for all tests orswitch box may be damaged.

Tb test ignition system, proceed asfollows:

IGNITION COILS PRIMARY CIRCUITOn models after serial number 5823917,connect DVA red test lead to ignitioncoil negative (-) terminal and black testlead to coil positive ( + ) terminal. Onearlier models, connect red test lead toignition coil positive ( + ) terminal andblack test lead to coil negative (-) ter-

Fig. M10-21^ Wiring dia-gram of eiectric starting oneariy 40 modeis and 402modeis. Ignition for manuaistart 40 and 402 is similar.External wiring harness inFig. M10-20 is common to aii

eiectric start modeis.

minal. Position tester selector sw itch to400 DVA. On early models, tester shouldread 150-250 volts at cranking or idlespeed (3004000 rpm) and 180-280 voltsat 1000-4000 rpm. On models after serialnumber 5823917, tester should read 100-250 volts at cranking or idle speed (300-1000 rpm) and 150-300 volts at 1000-4000 rpm. If voltage readings are belowspecified reading, refer to SWITCH BOXSTOP CIRCUIT test. If readings arewithin specifications, connect a suita-ble spark tester to ignition coil high ten-sion leads, crank engine and note spark.If weak or no spark is noted, renew ig-nition coil(s). If normal spark is noted,renew spark plugs. If malfunction is stillevident after renewing spark plugs,check ignition timing. If ignition timingis erratic, such as a sudden timingchange, inspect trigger advance linkagefor excessive wear or damage and innerflywheel magnets (shifted position orother damage). If timing is withinspecifications, problem is not in ignitionsystem.

SWITCH BOX STOP CIRCUIT On ear-ly models, connect DVA black test leadto engine ground and red test lead toblack/yellow switch box terminal (or-ange terminal on some early models).On models after serial number 5823917,connect red test lead to engine groundand black test lead to black/yellowswitch box terminal. Set DVA selector

IGNITIONSWITCH

IGNITION COILS

Fig. M10-22^ Wiring diagrBm of eiectric stBrting on late 40 modeis end 35 modeis, ignition system on manuBi start modeis is simiiBr.B. BlackR. RedY. Yellow B/Y. Black with yellow G/Y. Green with yellow

Gr. Gray tracer tracerB/W. Black with white G/W. Green with white Y/B. Yellow with black

tracer tracer tracer

Y/R. Yellow with redtracer

R/Pr. Red with purpletracer

Br/Y. Brown withyellow tracer



switch to 400 DVA. Voltage reading atcranking and all running speeds shouldbe 200-360 volts on all models. If read-ing is within specifications, refer to STA-TOR tests. If reading is above specifiedvoltages, disconnect trigger leads atswitch box and connect a suitable ohm-meter between trigger leads. Trigger re-sistance should be 800-1000 on earlymodels and 650-8500 ohms on modelsafter serial number 5823917. If not, re-new trigger assembly. If trigger resis-tance is acceptable, renew switch boxand repeat SWITCH BOX STOP CIRCUITtest. If SWITCH BOX STOP CIRCUIT testreading is below specified voltage, dis-connect ignition switch, stop switch andmercury switch from black/yellowswitch box terminal (orange switch boxterminal on early models). Make sureblack/yellow stator lead remains con-nected to switch box. With stop switch,ignition switch and mercury switch iso-lated, repeat SWITCH BOX STOP CIR-CUIT test. If reading is now withinspecification, ignition switch, stopswitch or mercury switch is defective.If reading remains below specificationrefer to STATOR test.

STATOR. On early models, connectDVA black lead to engine ground andred lead to blue switch box terminal. Onmodels after serial number 5823917,connect red test lead to engine groundand black test lead to black/yellowswitch box terminal. Set DVA selectorswitch to 400 DVA. Voltage reading onearly models should be 210-310 volts atcranking and idle speeds and 190-310volts at 1000-4000 rpm. Voltage readingon models after serial number 5823917should be 200-360 volts at all crankingand running speeds. Next, on earlymodels, switch DVA red test lead to redswitch box terminal or on models afterserial number 5823917, switch black testlead to black/white switch box terminal.Voltage reading on early models shouldbe 20-100 volts at cranking or idlespeeds and 140-310 volts at 1000-4000rpm. Voltage reading on models afterserial number 5823917 should be 10-100volts at cranking or idle speeds and 100-300 volts at 1000-4000 rpm.

NOTE: A shorted or open capacitor insideswitch box wiii resuit in fauity stator voitagereadings during cranking and running tests.Stator resistance shouid be checiced as fol-iows before faiiing stator.

If either STATOR test is not to specifi-cation, check stator resistance as fol-lows: On early models, resistance be-tween blue stator lead and engineground should be 5000-6000 ohms andbetween red stator lead and ground re-sistance should be 50-60 ohms. On

models after serial number 5823917, re-sistance between black/white statorlead and ground should be 120-180ohms, between black/yellow stator leadand ground should be 3200-3800 ohmsand between black/yellow andblack/white stator leads should be 3100-3700 ohms. Renew stator if resistance isnot as specified. If stator resistance isas specified, renew switch box and re-peat STATOR tests.

IGNITION COILS RESISTANCE TESTDisconnect wires and high tension leadfrom coiL Connect a suitable ohmmeterbetween coil positive ( +) and negative(-) terminals. Resistance should be 0.02-0.04 ohm on all models. On early models,connect ohmmeter between coil hightension terminal and ground. Resistanceshould be 900-1200 ohms. On models af-ter serial number 5823917, connectohmmeter between coil high tensionterminal and coil negative terminal. Re-sistance should be 800-1100 ohms. Re-new ignition coil(s) if resistance is notas specified.

NOTE: ignition coii resistance tests canoniy detect open or shorted windings, if coiiresistance is within specification and stiiisuspected as defective, coll must be testedusing DVA meter as previousiy outlined iniGNiTiON COiL test, if DVA meter is notavaiiabie, substitute a known good ignitioncoii and run engine to test.

All Models

Recommended spark plug is ACV40FFM or Champion L76V. ChampionQL76V may be used if radio noise sup-pression is required. Renew surface gapspark plugs if the center electrode ismore than V32 inch (0.79 mm) belowflush with flat surface of plug end. Ifrough low speed operation is noted on1971 400 models, AC M40FFX or Cham-pion L77J spark plugs gapped at 0.030inch (0.76 mm) can be used.

COOLING SYSTEM

WATER PUMP. The rubber impellertype water pump is housed in the gear-case housing. The impeller is mountedon and driven by the lower unit driveshaft. Model 402 is equipped with athermostat and a poppet type pressurerelief valve (Fig. MlO-24) mounted un-der the ignition coil bracket on top ofthe power head.

When cooling system problems are en-countered, first check the water inletfor plugging or partial stoppage, then,if not corrected, remove the gearcasehousing as outlined in LOWER UNITsection and examine the water pump,water tubes and seals.

When assembling, observe the assem-bly notes, cautions and tightening tor-ques listed in the LOWER UNIT section.

POWER HEAD

R&R AND DISASSEMBLE. Toremove the power head assembly, firstremove the top cowl and disconnect stopswitch wire, speed control linkage andchoke linkage. Remove nuts securingpower head to lower unit; then lift offthe complete power head assembly.

Place the unit on power head stand orequivalent and remove fuel pump, car-buretor, flywheel and ignition com-ponents. Exhaust cover plate (1-Fig.MlO-26), cylinder block cover plate (3)and transfer port cover (4) should beremoved for inspection and cleaning.

Remove cap screws that retain topend cap (5). Remove screws (20) thatsecure lower end cap (16) on 35, 40 and402 models and bearing retainer(10-Fig. MlO-27) on 35, 40, 400 and 402models. Unbolt and remove crankcasehalf (11-Fig. MlO-26). Use extra carenot to spring parts or to mar machined

Fig. M1024^Exploded view of typicai ther-mosiat and relief valve installation used onModel 402. Thermostat (13) is used on some 35

and 40 models.1. Cover 8. Spring2. Washer 9- Poppet valve3. Diaphragm 10. Washer4. Coil mount bracket 11. Grommet5. Grommet 12. Gasket6. Gasket 13. Thermostat



mating surfaces. Crankcase half (11)and cylinder block (13) are matched andalign bored, and are available only as anassembly.

The crankshaft and bearingsassembly, with pistons and connectingrods attached can now be lifted out ofcylinder block for service or overhaul asoutlined in the appropriate followingparagraphs. Assemble by following theprocedures outlined in the ASSEMBLYparagraph.

ASSEMBLY. When assembling, thecrankcase must be completely sealed

against both vacuum and pressure. Ex-haust manifold and water passages mustbe sealed against pressure leakage.Whenever power head is disassembled,it is recommended that all gasket sur-faces and machined joints withoutgaskets be carefully checked for nicksand burrs which might interfere with atight seal.

Completely assemble the crankshaftmain bearings, connecting rods, pistonand rings. Lip of lower end seals(15-Fig. MlO-26) should be down. In-stall screws (21-Fig. MlO-27) withheads toward top. Install the crankshaft

22

Fig, M10-26-Exploded viewof crankcBse end cyiinderblock assembiy typicBi of BU

modeis. Refer to text.1.2.3.4.5.6.7.8.9.

10.11.12.13.14.15.16.17.18.19.20.21.

Exhaust coverExhaust baffleCylinder coverTransfer port coverTop end capOil seal"0" ringBall bearingStarter motor bracketDowelCrankcase halfSealing stripsCylinder block"0" ringLower sealLower end cap"0" ringSealWasherScrewDowel

19 n 17 16

Fig. M10-27~ View of crank-shBft Bnd center mein beer-ing Bssembiy typicBi of thetype used on BU modeis,Beering retBiner (12) . BndspBcer (13) Bre not used onearly 402 modeis. Com-ponents (12 through 15) arenot used on 400 modeis.Components (13 through 15)are not used on 35 end iBte

40 modeis.1. Piston2. Piston pin3. Washer4. Needles5. Bearing cage6. Connecting rod7. Rod cap8. Rod screw9. Crankshaft

10. Bearing retainer11. Ballbearing12. Retainer ring13. Retainer spacer14. "0" ring carrier15. "0" ring16. Nut17. Reed stop18. Reeds19. Center main bearing20. Dowel pin21. Reed stop screw22. Bearing clamp screw

assembly by inserting pistons in lowerend of cylinders. Two special Mercuryring compressors should be used. If ringcompressor kit is not available, two menmust work together and use extremecare in installing the crankshaft andpistons assembly. Thoroughly lubricatethe pistons, rings and bearings usingnew engine oil and make sure that ringend gaps are aligned with the locatingpins in the ring grooves.

Make certain that end cap (5-Fig.M10-26) correctly engages dowel (10)and that retainer (10-Fig. MlO-27)engages dowel (21-Fig. MlO-26). Seal-ing strips (12) are used between halvesof crankcase (11 and 13) on all models.Apply a thin bead of Permatex 2C-12 ora suitable equivalent to mating surfaceof crankcase half prior to installation.On models so equipped, seals (18) shouldbe installed on the retainer attachingscrews (20). After crankcase is as-sembled, turn the crankshaft until eachpiston ring has been visible in the ex-haust and transfer ports and check fordamage during assembly. Turn crank-shaft several revolutions to make cer-tain that all parts are free and do notbind.

PISTONS, PINS RINGS ANDCYLINDERS. Before detaching con-necting rods from crankshaft assembly,make sure that rod and cap are proper-ly identified for correct assembly toeach other and in the correct cylinder.

Maximum allowable cylinder borewear or out-of-round is 0.004 inch (0.102mm) on 400, 402 and early 40 modelsand 0.006 inch (0.152 mm) on late 40models and 35 models.

Piston pin is pressed in piston bossesand secured with retaining rings. Pistonend of connecting rod is fitted with 29loose bearing rollers which use the con-necting rod bore and the piston pin asbearing races. Install bearing washersand needle bearings in piston end ofconnecting rod using light nonfibrousgrease to hold them in place. Heat pis-ton to 190° F (88° C), then install thepiston pin using Mercury special tool 91-76159A1. Pistons must be installed sosharp vertical side of deflector will betoward intake side and long sloping sideof piston will be toward exhaust port incylinder. Thoroughly lubricate all fric-tion surfaces during assembly.

CONNECTING RODS, BEARINGSAND CRANKSHAFT. Upper end ofcrankshaft is carried by ball bearing(8—Fig. MlO-26). The unbushed centermain bearing also contains the inlet reedvalves. Lower main bearing (11—Fig.M1027) is not interchangeable with theupper ball bearing.



Each connecting rod rides on 29 loosebearing rollers (4) at piston pin end andcaged rollers (5) at crankpin end. Checkrod for alignment, using Mercury Align-ment Tool C-91-2844A2, or by placingrod on a surface plate and checkingwith a light. Make certain that align-ment marks on connecting rods are bothon same side of rod during assembly.

Crankpin bearing surface of connect-ing rods should be cleaned with crocuscloth only. Piston pin bearing surface ofconnecting rod should be cleaned with#320 carborundum paper only.

If bearing surface of rod and cap isrough, scored, worn, or shows evidenceof overheating, renew the connectingrod. Inspect crankpin and main bearingjournals. If scored, out-of-round, orworn, renew the crankshaft. Check thecrankshaft for straightness using a dialindicator and "V" blocks.

Inspect and adjust the reed valves asoutlined in REED VALVE paragraph,and reassemble as outlined inASSEMBLY paragraph.

MANUAL STARTER

Early Type

Refer to Fig. Ml0-30 for explodedview of rewind starter assembly. Todisassemble, remove three stud nutssecuring motor top cowl to power head,pry rope anchor (22) out of starter han-dle and remove top cowl. Tie a slip knotin start rope to keep it from winding intohousing. Remove ignition triggerassembly on 400 models. Disconnectshift interlock cable (Fig. MlO-32) onlate 400 models and 40 and 402 models.Detach starter housing from top ofmotor. Insert a screwdriver in slot in topin sheave shaft (19-Fig. MlO-30) andloosen the left hand thread nut (3).Allow the screwdriver and shaft (19) toturn clockwise until recoil spring un-winds. Remove nut (3), invert theassembly and remove the parts, makingsure that recoil spring (7) remains inhousing recess as sheave (10) is re-moved. Protect hands with gloves or acloth, grasp the recoil spring (7), removespring and allow it to unwind slowly.

Lubricate the parts with MultipurposeLubricant, and assemble by reversingthe disassembly procedure. Installspring guide bushing (8) with chamferedend toward sheave (10). Make sure thatpawls (12) are all installed the same way,with radius to outside and identificationmark away from sheave (10). Install re-tainer (15) with cup end out and positionwasher (16) and wave washer (17) in cup.Make certain that tang on spring re-tainer (6) engages slot in sheave shaft(19). Position starter with end of shaft

(19) through housing (15) and installlockwasher (4) and nut (3). Pull free endof recoil rope through cowl or starterhousing and install handle (21) and an-chor (22). Turn sheave shaft (19)counterclockwise until handle is pulledagainst cowl, plus an additional IV4turns; then tighten nut (3). Pull cord outand check for sticking and full return.

NOTE: When checking, it will benecessary to hold starter lock (24) up.

The starter lockout (23, 24 and 25)used on early 400 models preventsmanual starter from being pulled at highspeed throttle settings. To adjust, locatethe locknut cam with Vs inch (3.175 mm)clearance as shown in Fig. MlO-31. Thetop screw should be located at front ofslot in cam. Adjustment is accomplishedby moving cam on bottom screw. The ig-nition control rod should push thelockout cam and lever up at slow speedsettings.

The shift interlock (Fig. MlO-32) usedon late 400 models and 40 and 402models is used to prevent starting withmotor in forward or reverse gear.Loosen screw holding cable clamp (C)and move cable until pin of toggle (T) isat mid-point of cam on sliding cam (SC)with motor in neutral. Tighten cableclamp screw.

4 3 23 24 25

Late Type

To remove the manual rewind starter,first remove the engine cover assembly.Remove the starter rope from the han-dle anchor and allow the rope to rewindinto the starter. Remove the starter in-terlock cable at the starter housing.Remove the screws retaining themanual starter to the engine. Withdrawthe starter assembly.

To disassemble, bend tabs of tabwasher (4-Fig. MlO-33) away from nut(3). Insert a screwdriver in slot of sheaveshaft (19) and loosen the left-handthread nut (3). Remove nut (3), invertstarter housing (5) and remove manualstarter components. Make sure that therewind spring remains in pulley recessas the starter pulley is removed. Use

Fig. M10-30-Exploded view of the recoil starterused on 400 models. Unit used on Models 40 and

402 is similar.1. Pulley2. Spacer H. Spacer3. Nut 15. Retainer4. Lockwasher 16. Washer5. Housing 17. Wave washer6. Retainer 18. Plate7. Rewind spring 19. Sheave shaft8. Bushing 21. Handle

10. Sheave 22. Anchor11. Wave washers 23. Spring12. Pawls 24. Iijckout lever13. Bushing 25. Cam

Fig. M10 3i-Refer to text for adjusting themanual starter lockout cam.

Fig. MiO32- View of shift interlock used on ear-ly Model 40, Model 402 and late Model 400.



suitable hand protection and extract therewind spring from the starter pulley.Allow the rewind spring to uncoil in asafe area.

Inspect all components for damageand excessive wear and renew if needed.

NOTE: During reassembly, lubricate allfriction surfaces witfi a suitable lowtemperature grease.

Assemble by revers ing thedisassembly procedure. Be sure thatpawl (12) is installed with the radiustoward the outside and the identificationmark (dot) away from sheave (10). Onearly models, install washer (25) withcupped side facing away from sheave(10). Make certain that tab on spring re-tainer plate (6) properly engages rewindspring (7) loop during installation.

With the manual starter assembly pro-perly assembled, install tab washer (4)and nut (3). Pull free end of starter rope(27) through housing (5) and secure witha knot approximately 1 foot (30 cm)from rope end. Place a suitable sizescrewdriver blade in sheave shaft (19)slot. Turn sheave shaft counterclock-wise until starter rope knot is pulledagainst the rope guide, then continue toturn the sheave shaft an additional 2 fullturns. Tighten nut (3) and bend tabs oftab washer (4) to secure nut (3) in place.Bend one tab on tab washer (4) into

starter housing hole. Pull the starter outto full length while checking for freedomof travel, then allow the starter rope torewind slowly onto the starter pulley.

Remount the manual s tar terassembly. Adjust starter lockoutassembly by varying position of opera-tion cable. Starter should engage whengear shift lever is in the neutral position,but not engage when gear shift lever isin the forward or reverse position.

Install the engine cover assembly.Feed the starter rope through theengine cover opening and starter han-dle. Secure rope end with handle anchor.

LOWER UNIT

PROPELLER AND DRIVECLUTCH. Protection for the motor isbuilt into a special cushioning clutch inthe propeller hub. No adjustment ispossible on the propeller or clutch.Various pitch propellers are availableand propeller should be selected for thebest performance under applicable con-ditions. With speed control linkage cor-rectly adjusted propeller should beselected to provide maximum speed of5400-6000 rpm on 35 hp models and5000-5500 rpm on 40 hp models. Pro-pellers other than those designed for themotor must not be used.

Fig. MiO-33-Expioded viewof manual rewind starterused on late Model 40 and

Model 35.1. Pulley2. Spacer3. Nut4. Tab washer5. Housing6. Retainer7. Rewind spring8. Bushing

10. Sheave12. Pawl14. Spacer17. Wave washer19. Sheave shaft21. Handle22. Anchor23. Spring24. Clip25. Washer26. Lever27. Starter rope28. Interlock cam29. Spring30. Interlock actuator31. Spring32. Interlock cable

R&R AND OVERHAUL. Most serv-ice on the lower unit can be performedby detaching the gearcase housing fromthe drive shaft housing. To remove thehousing, remove the plastic plug andAllen head screw from location (1 - Fig.MlO-35). Remove trim tab (2) and studnut from under trim tab. Remove thestud nut from location (3) and the twostud nuts (4) from each side then with-draw the lower unit gearcase assembly.

NOTE: Do not lose plunger or spring (67and68—Fig. M10-36).

Remove the housing plugs and drainthe housing, then secure the gearcase ina vise between two blocks of soft wood,with propeller up. Wedge a piece ofwood between propeller and antiventila-tion plate, remove the propeller nut,then remove the propeller.

Disassemble the gearcase by removingthe gearcase housing cover nut (61 - Fig.MlO-36). Clamp the outer end of pro-peller shaft in a soft jawed vise andremove the gearcase by tapping with arubber mallet. Be careful not to lose key(59) or shims (47) on early models. For-ward gear (40) will remain in housing.Withdraw the propeller shaft from bear-ing carrier (56) and reverse gear (46).

Clamp the bearing carrier (56) in asoft-jawed vise and remove reverse gear(46) and bearing (49) with an internal ex-panding puller and slide hammer.Remove and discard the propeller shaftrear seal or seals (58).

To remove dog clutch (43) from pro-peller shaft, remove retaining ring (44).Insert cam follower (8) in hole in shaftand apply only enough pressure on endof cam follower to remove the springpressure, then push out pin (42) with asmall punch. The pin passes through

Fig. M10-35—TO remove the tower unit gearcaseassembly, remove the Allen head screw and stud

nuts from location indicated.



drilled holes in dog clutch and operatesin slotted holes in propeller shaft.

To disassemble the drive shaft andassociated parts, reposition gearcase invise with drive shaft projecting upward.Remove rubber slinger (11), water pumpbody (16), impeller (19) and impellerdrive pin (20). Remove the flushingscrew and withdraw the remainder ofthe water pump parts. Clamp upper endof drive shaft in a soft jawed vise,remove pinion retaining cap screw ornut (37); then tap gearcase off driveshaft and bearing. Note the position andthickness of shims (30) on drive shaft up-per bearing. Mesh position of pinion iscontrolled by shims (30) placed under-neath the bearing.

After drive shaft has been removed,the forward gear (40) and bearing conecan be withdrawn. Use an internal ex-panding type puller to withdraw bearingcup if removal is required. Remove andsave the shim pack (38).

Shift shaft (5) and cam (7) can beremoved after removing forward gearand unscrewing bushing (3) from gear-case housing.

If gear wear is abnormal or if anyparts that affect gear alignment wererenewed, check and adjust gear mesh asfollows: Install forward gear (40) andbearing (39) using shims (38) that wereoriginally installed. Position shims (30)that were originally installed at bottomof bearing bore, then install bearing cup(32) in housing bore against shims (30).Position the drive pinion in housing andinsert drive shaft (33), with bearing (32)installed, into housing, bearing (34) andgear (35). Install the retaining nut (37).Coat gears (35 and 40) with bearing blueand check mesh position. It will benecessary to push down on end of driveshaft while checking mesh position. Ifgears do not mesh in center of teeth, addor remove shims (30) under bearing asnecessary. After setting mesh position,check backlash between teeth of gears(35 and 40). Backlash should be withinlimits of 0.003-0.005 inch (0.076-0.127mm) on 400, 402 and early 40 modelsand 0.007-0.010 inch (0.178-0.254 mm)on 35 and late 40 models. To increaseclearance (backlash), remove part ofshim stack (38) behind bearing cup. Ifgears are too loose, add shims. Afterchanging thickness of shims (38), gearsshould be recoated with bearing blue andmesh position should be rechecked. In-stall bearings (49), thrust washer (48)and reverse gear (46) in bearing carrier(56). Then, install bearing carrier andgear assembly using shims (47), on earlymodels, that were originally installedand check backlash between gears (35and 46). If backlash is not within thelimits of 0.003-0.005 inch (0.076-0.127

mm), add or remove shims (47) as re-quired. Adding shims (47) increasesbacklash (clearance).

When reassembling, long splines onshift rod (5) should be toward top. Shiftcam (7) is installed with notches up andtoward rear. Assemble shifting parts (9,8S, 43, 42 and 44) into propeller shaft(45). Pin (42) should be through hole inslide (8S). Position follower (8) in end ofpropeller shaft and insert shaft intobearing (41) and forward gear. Installthe reverse gear and bearing carrierassembly using new seals (55 and 58).Lip of seal (58) should face propeller(out) on single seal models. On two sealmodels, install inner seal with lip towardreverse gear and outer seal with liptoward propeller.

Upper oil seal (26) should be installedwith lips facing up (toward engine) andlower oil seal (27) should be pressed intowater pump base with lips facing downtoward propeller shaft. Install re-mainder of water pump assembly andtighten the screws or nuts to the follow-ing recommended torque. Torque V4-28nuts to 25-30 in.-lbs. (2.8-3.4 N-m). Tor-que 5/16-24 nuts to 35-40 in.-lbs. (3.9-4.5N-m). Torque V4-20 screws to 15-20in.-lbs. (1.7-2.2 N-m).

Fig. M10-36-Exploded ¥iewof typicBi geBrcBse Bssem-bty. Two oil seBis (1) Breused on some models. TwoseBis (58} Bre used on iBtermodels. Shim (47) is notused on iBter models. OniBter models, B nylon wBsher

replBces spacer (2L).I. Oil seal

2C. Reverse locking cam2L. Spacer

3. Bushing4. "0" ring5. Shift shaft6. Snap ring7. Shift cam8. Cam follower

8S. Slide9. Spring

10. "O" ringII. Rubber ring (slinger)12. Oil seal14. Seal15. Nylon washer16. Water pump body17. Gasket18. Rubber washer19. Impeller20. Key21. Insert22. Plate23. Pump base24. Gasket25. Dowel26. Oil seal27. Spring loaded oil seal28. "0" ring29. Gasket30. Shims32. Tapered bearing33. Drive shaft34. Roller bearing35. Drive pinion37. Nut38. Shim39. Tapered roller bearing

On early models, the reverse lockingcam must be installed on shaft splinesso the two tabs are aligned with the leftfront stud when in FORWARD gear(clockwise) position. Refer to Fig. MIO-37. On later models, place shift shaft(5—Fig. MlO-36) in neutral position. In-stall nylon washer with grooved sidedown and position reverse lock cam(2C-Fig. MlO-38) with high point (H) ofcam positioned as shown in Fig. MlO-38.

Later models are equipped with twoseals which fit over upper drive shaftsplines. Install splined seal on driveshaft splines with splined seal end to-ward top of drive shaft, then install re-maining seal with small end toward topof drive shaft.

Before attaching gearcase housing tothe drive shaft housing, make certainthat shift cam (7-Fig. MlO-36) and theshift lever (on motor) are in forwardgear position on models with reverselocking cam shown in Fig. MlO-37 andneutral position on models with reverselocking cam shown in Fig. MlO-38. Com-plete assembly by reversing disassemblyprocedure.

Make certain that spring (68—Fig.MlO-36) and plunger (67) are positionedbefore attaching gearcase to drive shafthousing.

WL

40. Forward gear41. Roller bearing42. Cross pin43. Dog clutch44. Retaining ring45. Propeller shaft46. Reverse gear47. Shim48. Thrust washer49. Ball bearing

50. Exhaust tube seal51. Support plate52. Gear housing53. Vent screw54. Filler screw55. "0" ring56. Bearing carrier57. Roller bearing58. Oil seal59. Key

60. Washer61. Housing cover nut63. Thrust hub64. Cupped washer65. Spline washer66. Propeller nut67. Plunger68. Spring69. Lubrication sleeve

Illustrations courtesy Mercury235


Ummx &*v«)r»*

Fig, M10-37-On early models, the reverse iockcam must be Installed on shift splines as shown

when in forward gear position.

Fig. MtO-38-On later modeis, the reverse iockcam (2C) must be instaiied on shift spiines withhigh point (H) of cam positioned as shown when

in neutrai position.

POWER TILT/TRIM

FLUID. Recommended fluid is SAElOW-30 automotive oil. With outboardin full up position, oil level should reachbottom of fill plug hole threads (Fig.MlO-40). Do not overfill.

BLEEDING. Tb determine if air ispresent in tilt/trim hydraulic system,trim outboard out to trim limit position,then pull up on lower unit. If trim cyl-inder pistons retract into cylinders in ex-cess of Vs inch (3.2 mm), air is presentand should be purged from system.

Make sure manual release valve is infull counterclockwise position and openvent screw (Fig. MlO-40) two turns.Make sure pump reservoir is full of oil.Tb bleed system, operate tilt/trim systemthrough several full up and full in cy-cles, checking oil level in reservoir ateach full up position.

ADJUST TRIM LIMIT SWITCH. Op-erate trim control so outboard is in fulldown position. Press "UP/OUT" or"UP" control button and hold it untilpump motor stops. Outboard should tiltup and stop so there is V2 inch (12.7 mm)overlap (L—Fig. MlO-41) between swiv-el bracket flange (W) and clamp brack-et flange (M). Pull up on lower unit toremove slack when checking overlap(L). Note that if cylinder rods entercylinders more than an additional Vginch (3.2 mm), air is present in hydrau-lic system and should be purged as out-lined in BLEEDING section. If overlap(L) is incorrect, loosen retainer screw

(R-Fig. MlO-42), then turn adjustingnut (N) counterclockwise to increaseoverlap or clockwise to decrease over-lap. Retighten retainer screw (R) andrecheck adjustment.

PRESSURE TEST. Tb check hydrau-lic system pressure, disconnect fourhoses attached to control valve asshown in Fig. MlO-43; small hoses arefor up circuit while large hoses are fordown circuit. Connect a pressure gageto one up circuit port of control valveand another pressure gage to one downcircuit port. Screw plugs into remainingports. Check fluid reservoir and fill if

Fig. M10-42—Loosen retainer screw (R) and turntrim iimit adjusting nut (N) to adjust trim limit

switch.

Fig. M10'40^View showing power tlit/trim systemfiii plug and reservoir vent piug.

Fig. MW-41—Overiap (L) between swivei bracketfiange (W) and clamp bracket flange (M) should

be '/2 inch (12.7 mm) minimum.

Fig. M10-43^View of controi valve showing ioca-tlon of up circuit hoses (U) and down circuit hoses

(D).



necessary. Operate trim control in up ry 15 seconds. Operate trim control in faster than 100 psi (689.5 kPa) every 15direction until maximum pressure is in- the down direction until the maximum seconds. If pressure is normal, inspectdicated on gage. Minimum up pressure pressure is indicated on the gage. Down trim cylinders and hoses for leakage. Ifis 2700 psi (18.6 MPa). After releasing pressure should be within 500-1000 psi pressure is abnormal, install a knowntrim control button, pressure will drop (3.4-6.9 MPa). After releasing trim con- good control valve and recheck pres-slightly after stabilizing but should not trol button, pressure will drop slightly sure. If pressure remains abnormal, in-drop faster than 100 psi (689.5 kPa) eve- after stabilizing but should not drop stall a new pump body.

237

Mercury Service Manual

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