evinrude lower unit

[craigcraftdave]

i am not sure where to post this but i need to rebuild the lower unit on my 57 evinrude fastwin 18 and i need to know what year range the parts are used on it looks like the 68 evin18 is the same lower and i can order parts for a 68 very easily , dave

[JohnsonM50]

i am not sure where to post this but i need to rebuild the lower unit on my 57 evinrude fastwin 18 and i need to know what year range the parts are used on it looks like the 68 evin18 is the same lower and i can order parts for a 68 very easily , dave

I think those older ones had kind of a blunt nose cone shape, then on later ones the gearcase had no cone shape. If the housings the same externally then probably the same inside. Look at screw, drain/fill plug & pivot-screw locations for differences. Parts are still around, may need to shop tho. Whats wrong that it needs a rebuild? The clutch dog?.. or leaking + subsequent chain reaction of bad news is about all they're vulnerable too. Or the pivot screw gets removed by mistake lols

[craigcraftdave]

Well I had a leak and crap in the gear case and i have six lowers so i am restoring my motor and just want to re build the lower and make it like new instead of putting a old leaky one on. I hope to avoid break downs

[JohnsonM50]

The hardest part of the job may be the screws, getting em out. They are #3 phillips usually & too tight to substitute a #2 for. I find that a typical battery-clutch drive drill works well because you can start the clutch light & increase as needed. This does 2 things, vibrate the heck out of em & since you 'can' hold it from slipping- save the screw heads. Beyond that a heavy duty screwdriver w/ visegrips. [hold the driver in with 1 hand, turn the visegrips with the other] or one of the hammer smack type impact drivers. These work well but limit the blows to not too hard.
Once apart the leaks can be from several to all places at once. The seal under the waterpump, the shift rod bushing & the housing seal. Then the most likely & the worst. The rear bushing/seal assembly $115.oo last I bought one. The actual seal can be dug out of the thing but is difficult, typical seal encased in it. You might also find a groove worn into the shaft, if severe it will leak seal or not. Its not a bad idea to put a new clutch dog in, even a small amount of rounding over & it can start popping out of gear. Once it starts it gets worse as ya go, unless it looks real good.. a thought.
Ive worked with one of these extensively to get it to go fast. Eventually it reached 50+ at 7+Gs rpm. on a hydro. By then the clutch dog was pinned into full time forward. The reverse gear teeth were ground off [the gear hub acts as a spacer now & spins with the shaft not against] The shift linkage is gone, the hole plugged. Now the thing finally holds up . It leaked so bad once that after a long day clear water drained out of it. That was under abusive to normal spec conditions tho & done right yours should last a long time.
I saw something on the AOMCI site about a sleeve to fix the seal groove thing. If you need go to AOMCI -ask a member, free, no need to be a member & usually a few OMC 'BOOK' guys there. Good Luck.

[Skoontz]

The leak is usually the gearcase head and seal. Use a hit it style 3/8" impact driver, and if they won't rock out, then use a propane torch on the upper case where the screws thread into it. If propane won't do it, use oxy acetylene, move it up and down fast on the case. Make sure you rub a 600 degree temperature stick on it. If the stick melts, pull the torch off quick.

I've never had a screw win using this system.

The guts on the pre '66 case will be the same, however the driveshaft splines changed when the case style changed. You can retro fit the old style driveshaft into the new case. Make sure you change the spaghetti gasket if you can when you split the cases, especially if you had to use heat to undo the screws.

[Bill Gohr]

OK well guys the 57' didn't have phillips screws, they were slotted, there are 2 different style gears in them in the 50's and 60's. Straight and spiral. Anyway, I have the parts cards for the old ones here if you want me to check the numbers for you. As well, we have numerous old dealers here that will have anything in stock if you can't get them, I will get them for you. Generally the shafts get grooved. All you need is 2 seals, 2 orings, 1 spag seal 309044 (I remembered that one) and 2 washers for the fill plugs 311598. If they've been run with lots of water in them the bronze bushings will be shot, if you have 6 of them I'm sure you will have a set of good enough parts

[craigcraftdave]

Well i have lots of gears and bushings so i am sure i can find good ones. i just need all the seals o rings and an impeller. if you know a good place to get them i could send you some money for them and your time i just want to know what it is going to cost first, dave

[jeff55vDSH]

NAPA used to sell seal kits for bunches of the ol' OMC's. They had #18-2684 for 1958-73 18hp motors (and a bunch of others). It included everything you needed to replace all the oil stoppers in those. It's been a long time since I dealt with that stuff. Perhaps they still have the item available.