Who knows how long it had been sittingin the garage.When we took possession ofthe 1989 Yamaha 2-stroke, 2-horsepoweroutboard motor, it was unused, unloved,had seized up, and was collecting dust.Wehad no idea what wed find under theproverbial hood and werent certain itcould be repaired.While our expectationswere low, our assignment was simple:Takethe engine apart, diagnose its problem, andget it running againand hopefully have a

little fun in the process.In the end, the project took two full

days and cost around $70 for a completeset of replacement gaskets, O-rings, oilseals, impeller, and new water-pump hous-ing. Other parts also might have benefitedfrom replacing, but we took a wait-and-see approach with these.We could alwaysswap them out later if the motor actuallyworked. We used just basic toolswrenches, sockets, screwdrivers, and pli-

erswith a few extra items like lubricant,a hammer,Vise-Grips, and some sandpaper.We also bought an illustrated shop manu-almany of these are available fromInternet book sellersthat proved invalu-ble. Finally, the photos we took to docu-ment this story came in handy when weput the engine back together. If you have adigital camera, take some snaps along theway; youll be happy you did.

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OUTBOARD REBUILDSeized motor? Dont be so quick to junk it. With a little time and the right spares, you could bring a dead outboard back to life By Dave Baldwin

ENGINESSKILL LEVEL

HARDEASYTIME 16 HOURS (ONE DAY TO TAKE IT APART, ANOTHER TO PUT IT BACK TOGETHER)

CHECKLISTTOOLS Basic tool kit

Wrenches and sockets (metric if youre working on a European or Japanese engine)

Screwdrivers

Propane blowtorch

Rubber mallet

Hammer

Razor blade

Pliers

Vise-Grips

Vise

400-grit wet/dry sandpaper

Brush for applying grease and lubricating oil

Torque wrench

Outboard-engine manual

MATERIALS At minimum, a new set of

gaskets, but other spare parts may be required

Waterproof grease (make sure its graphite-free; graphite can corrode engine components)

Oil-Gasoline mixture

Kerosene

Penetrating oil

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1After wiping off themotor with a wet rag,we got down to businessdraining any remaininggasoline from the fuel tankand oil from the gearcase.

2Using a vise,we clamped theengine to a work-bench and removedthe side panels.

3Next we disconnected thespark-plug wire and pulledthe spark plug. It was coveredwith soot, but was otherwise ingood condition, so we cleanedit off for possible reuse.

4The control panel was tricky to remove at first butafter locating two hidden nuts underneath, it slid offjust fine. Although the choke knob was loose and the stopbutton seized, we opted against replacing either part untilwe ensured that the engine would work.

5With the control panel off, wewere able to disconnect the stop-switch leads, capacitor dischargeignition (CDI), and remaining electricwiring. All wires were color-coded soreassembly was a snap.

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UPPER-UNIT DISASSEMBLY

TOP TIP We put all nuts, bolts,screws, and washers into care-fully labeled plastic cups foreasy access during reassembly.

The spark plug is a goodindicator of the engines condi-tion. While soot covered thisplug, it was actually in goodshape. We tested it by pullingon the starter cord and lookingfor a spark.

6We took off both the recoil starter housing andthe fuel tank (after detaching the fuel line fromthe carburetor), although we decided not to disas-semble the starter and flywheel before further inspec-tion (it can often be left intact). Disassembling theflywheel may require special tools.

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7So far, so good. Next, weremoved the cylinder headand inspected the piston, find-ing it in good shape. We lubri-cate the piston, but the fly-wheel still struggled to turn.

8Off with the carburetor, reedvalve, and intake manifold.Surprisingly, the connecting rod alsolooked good, so we kept our fingerscrossed and hoped the problem mightlie outside the motor.

9After a significant struggle that required the use of woodenwedges, we disconnected the power head from the drive shafthousing. Eureka moment number 1. The flywheel spun while the pis-ton and rod moved freely. We sprayed more lubricant inside toloosen them up further. The propeller, on the other hand, still would-nt turn despite being freed from the motor. We were getting warmer.

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10First we pulled the propeller cotterpin and detached the propellerbefore sliding the entire lower unit out ofthe drive shaft housing.

11With the lower unit now clampedto the bench with a vise, weremoved the carrier and gasket, butinspected only the propeller shaft andgear. They looked fine so we decidedagainst taking it all apart.

12Next we opened and disassembledthe water pump. Eureka momentnumber 2. What a mess. Only two of the sixblades remained on the impeller; bits of theothers vanes fell to the floor. The inside ofthe pump housing was rusted and the oilseals were damaged. Both of them prevent-ed the drive shaft from turning. Houston, wehave the problem.

13We extracted the drive shaft fromthe drive-shaft tube and found it tobe rusted as well. Clearly, water had beencircumventing the seal and entering thedrive-shaft tube rather than exiting viawater-pickup tube. Careful examinationlater revealed that someone had crimpedthe drive-shaft tube in order to get it backinto the water-pump housing.

LOWER-UNIT DISASSEMBLY

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14After ordering replace-ment gaskets, oil seals,and a water-pump housing, weorganized all engine parts onthe workbench.

15Using a propane blowtorch and hammer, wedetached the drive-shaft tube from the corrod-ed water-pump housing. Since the end of the tube hadbeen crimped, we used a piece of rod rigging to force asocket of equivalent diameter through the tube, thus

reshaping it to as close to original as possible. Thisworked as a jury rig, but it would have been better toreplace the tube. NOTE: A propane blowtorch can beuseful in removing rusted or stuck parts, but be care-fulit can cause irreparable damage.

REASSEMBLY

REPLACING OIL SEALS

17-19We fitted a new O-ring into the top ofthe housing (it slides into an interiorgroove) and brushed it with oil. Then welubricated the inside and inserted thetwo oil seals, using a socket to pressthem completely into place.

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16The 1989model of thisengine has two oilseals inside thewater-pump housing.

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GEAR CASE & WATER PUMP

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20We sanded the rustoff the drive shaftand covered it with water-proof grease. After shootinga generous amount ofgrease into the drive-shafttube, we reinserted itthrough both the tube andwater-pump housing.

21Using kerosene and400-grit sandpaper,we cleaned the water pumpplate and refit it to the bot-tom of the housing. Whilewe were at it, we gentlyscrubbed the seal protectorand top of the gear casewith kerosene.

22With the impeller drive pin insertedinto the drive shaft, we slid on the newimpeller and reinserted the drive shaft into thegear case, attaching with bolts properlylabeled in the plastic cups. IMPORTANT: Makesure the impeller is inserted with the vanesbent in the direction of rotation. If not, it willhave difficulty turning, the blades could breakoff, and the pump wont work.

23A steady hand anda pair of needle-nose pliers were needed toreinsert the thrust washer,shim, pinion gear, and Ering, the latter being one ofthe toughest parts to bothput on and remove.

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1. Drive shaft2. Pin3. Water tube4. Seal5. O ring6. Water pump housing7. Oil seals8. Plate9. Impeller10. Liner/seal protector11. Seal12. Cavitation Plate13. Dowel pin14. Bushing15. Gearcase16. Vent plug

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17. Drain plug18. E ring19. Pinion gear20. Thrust washer21. Shim22. Bearing23. Shim24. Shear pin25. Propeller shaft &gear

26. Gasket27. Carrier28. Oil seal29. Propeller30. Cotter pin

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2826Next we inserted a new O-ring intothe exhaust plate and brushed

with oil. After inserting the new gasket, wereattached the cylinder block. Workingfrom inside out, we tightened the cylinderblock in equal amounts until reaching thefinal specified torque of 7 ft-lbs.

27With the cylinder head scrapped,we attached the new gasket andrebolted it to the cylinder block.

28At this point, we were simplyworking in reverse order. The reedvalve and intake manifold were attachedto the crankcase next, and we made cer-tain to first insert a new gasket. An airleak will make the engine run weak andcould cause an overheating situation.

24Next we reassembled the gearcase with a new gasket and carri-er and attached a new sacrificial zincanode to the bottom (compare the new andold anodes). Then we reinserted the gearcasewith brass water-pickup tubeattachedinto the drive-shaft housing.Were half way home.

25Using a razor blade and a vacu-um cleaner, we scraped the oldgaskets off the exhaust plate, drive-shafthousing, and cylinder head.

TOP TIP Use a vacuum or shop-vac tosuck up dust as you scrape awayold gaskets with a razor blade. A correctly-sized socketmakes an ideal tool for press-ing oil seals into place.

While we didnt thoroughlyscrub and soak all partsbefore reassembly, we did usekerosene to clean vital com-ponents.

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29Next we reattached the carburetorto the intake manifold, fuel tank,and manual recoil starter assembly. Dontforget to reconnect the fuel line.

30While the color-coded wires madereconnecting the electrics astraightforward task, we did consult our pic-tures to determine where exactly to mountthe CDI.

31Now for a quick test of the spark plug.Pulling the starter cord, we got a sparkto jump across. This plug is still good, but wewould have fitted a new one had we rememberedto buy one.

32Almost there. We reat-tached the controlpanel, replaced the covers,bolted the handle back on, andremounted the propeller andshear pin. Then we filled thegearbox with oil (shooting the oilup to force air out) and the tankwith a 50-50 gas/oil mix.

33And now the momentof truth. After sever-al minutes of pulling thestarter cord, we finally gotcontact. A whirl of smokefumed out, and it startedpurring like a cat. Successnever felt so good. This motoris back in business. BW