lower end seals needed when replacing impeller, '63 lightwin

backwater52

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Going to replace impeller on a 3 hp. What else should i get and what else should be checked while it's apart? And where to buy parts, this site doesn't seem to list any for older motors. It's a 1963 3hp lightwin, thanks
 

lindy46

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Impeller is available right here:
https://www.iboats.com/shop/sierra-w...s-18-3001.html
or if you want genuine OMC part # is 434424.
Check for water in the gearcase. If you see any, you may need to replace the driveshaft or propshaft seal. Also replace the crush washers on the fill and drain screws. Those are available here. Propshaft and Driveshaft seals are the same: 327031.
 

oldboat1

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If the gear case oil is milky, empty it and pressure test to locate leaks. You can do that by pumping a few lbs of pressure into the drain hole, closing the vent hole. Spray some soapy water around the driveshaft base -- no shift shaft to be concerned about. Simply replacing drain and vent washers also may take care of leaks.

Don't try to fix what ain't broke. If the pump is working, you will get misting from the openings on the leg. No tell-tale on that motor. If it's a salty, beware of breaking bolts (presoak with ATF, rock back and forth, etc.).
 

backwater52

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I'm picking it up today, decal's in pic look like 1963, if so could be 3302, 3303, 3312. From the pic's it's a short shaft and he say's it runs fine and compression good, will see. Unless i trip over a cheap grumman sport boat will have no use for it for a while so me and grand son can take care of any tune up, general maintenance work. I never worked on a B/M before but lots of chain saws and cement saws so not completely in the dark. If the power head is bad at least we will have a cheap practice unit. thanks for the help/info, will ask Q's here when i get my hands on it.
 

backwater52

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Got it home but no time to really check it out. Has new plugs, autolite 303's wires look good too. Prop seems to have side to side play and not sure if it's missing a cap over it. Fuel line nut is buggered up. Couple pic's what are the empty stud holes behind the fuel line? Thanks again.
 

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backwater52

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missing the nose cone at least.
 

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racerone

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Those holes might be where you would mount one of the wee square fuel pump to run off a bigger tank.----Remove the plug between those holes for the pulse port.
 

oldboat1

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If mine, I would begin with Champion J4C plugs, and make sure the plug wires have a solid core (stranded, or single copper). The prop will be OK that way while you get it up and running. The prop nut appears to be the correct one — takes a rubber nut cap when you get one.

Be careful with the shut-off valve as they are a little delicate. There is an integral filter that might turn to powder if you try to twist it — probably best to leave it alone. Look in the tank for debris, and smell it for old fuel. The motor will be happy with a 24:1 mix.

Are the nut threads for the fuel line buggered up, or the threads in the carb? I would need to check mine, but think you need that carb port for both the installed tank and a fuel pump and auxiliary tank.

Check it for spark with an adjustable open-air tester — look for 3/8” or more. If the coils under the flywheel have cracked cases, they will need to be replaced. I would get new points and condensers. Install one side at a time so you have an assembled side to check. Gap plugs at .030”, and points at .020”.

May need to disassemble and clean carb, but when all is finished they are great little motors.
 

backwater52

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Need to get a good puller, have sprk tester. Love the one side at a time approach, like drum brakes. The inside of tank looks like it had been chemically cleaned, mostly bare pitted metal. Probably toilet cleaner, hope it's solid. Anyway on hold. Life is strange, one death, two in hospital all separate illness's and lost my workshop to storage all in 6 hr's. Regroup next week i hope.
 

oldboat1

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Best to you. Obsessing over a meaningless project sometimes not a bad idea. Keep posting progress, or lack of it. :)
 

kbait

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Plug chart calls for Champion J6C (NGK B6S) plugs for non-thermostat outboards like the 3hp’s, J4C (B8S) for those with a thermostat.
 

backwater52

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Pulled lower covers off and checked spark. Very good spark so i mixed up a 1/2 gallon of 24:1 (more like 20:1) and filled a half barrel of water and got it to fire up once after 8 pulls. Died before i could fiddle with it. Then fuel wss dripping off front bottom of carb. SS knob dosent engage the needle valve so i had to turn it in with pliers then backed it out 1 1/2 turns. Tried for an hour but never poped again. Pulled & dried plugs and pulled the starter with fuel off a couple times to dry it out but no luck . Compression seems good but will check it this week end. Cant do much more till i get my garage back.
 

racerone

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If spark can not jump a gap of 1/4" + you do not have " very good spark " -----That would make it hard to start.
 

backwater52

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getting over 3/8ths blue spark so when i can get some room to turn around i will do the carb and check out the ignition more.
 

backwater52

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Got lucky i think, coils and points look good and fairly new plus great spark. Need carb kit but ran it a little by opening and closing the fuel **** so it didn't flood. Fuel **** leaked but tightened it up but if that don't work will try to repack it. Oil looks good in lower to but couldn't see if impeller was working while keeping it running. So carb kit, impeller, maybe seals and O-rings. Have a owners manual coming but could anyone suggest a repair manual, i cant find any for this motor.
 

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Last edited:

lindy46

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is there a seal or gasket between gear case and lower leg housing?

No. Clean those points with business card stock dipped in acetone. Those points should be open to. 020" when you see them in the inspection window. They appear closed to me.
 
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