OMC Lower Unit Sealant and Questions

[fleetwin]

I’m not sure what you mean when you say "end play". Are you saying the prop shaft slops side to side? Or, are you saying the prop shaft can be pulled in and out in the gearcase excessively?
Funny you should mention a leaky prop shaft seal. I am having the same problem on a 40hp Bigtwin gearcase charity job I’m doing. I was so discouraged seeing those air bubbles during the pressure test (in water bucket), I just kind of put the project aside. I used a new OMC prop shaft seal. Admittedly, it is tough to press that seal into the housing without the proper tool, which I did NOT have. I couldn’t get the seal square in the housing and ended up seating it all the way into the housing. I remember looking at the prop shaft, not seeing any problems in the sealing area. The way the seal housing is made, it is tough to determine if the leak was coming from the actual seal, or from a problem between the seal case and aluminum housing, like others have mentioned.
One thing is for dang sure, this is a job you only want to do once! The thought of pulling that skeg back off, cleaning up all that 847, and resealing again is upsetting. Use the proper sealers, OEM parts, and take your time!

[raglover]

Going to tear into it tonight take measurements etc. I am very familiar with these lower units or so I thought and I agree there should be no play on the aft end.

Will research both my parts and the books but did they run a different size Ball bearing….like a bigger ID and I just missed it?

Will post late tonight

[raglover]

Well I have the answer and I am VERY embarrassed.

Pulled the skeg off and a major component was missing……the ball bearing at the rear. This is a very bad mistake and resulted in the destruction of the internals of the lower unit, mostly due to water intrusion I did not know about until it was too late.

I know where it went wrong so I will share with others a basic thing I should know. NEVER get too many parts on the table at once. I had too many lower units apart on the bench at the time and was in a rush.

Now for the amazing part. That motor ran with no issues for 5 days on Lake Lure and stayed in the water the whole time. Gears were intact but were rusty. All bearings and bearing surfaces pitted and water marked.

Now that it is established I made a very costly mistake, for the questions.

1. What is the likely hood the housing is still good–I see no wear on the walls or obvious damage–would like to keep it if possible due to paint match
2. If housing is good I want to swap in the internals from a 33 ski twin that has a mismatched lower unit and is not good for use as an assembly–issues? I know it has the detented prop shaft but all else should work I think if I swap it all
3. How do I remove the pinion bearing housing–heat and patience, drive out from the top? I know there is the pinion bearing, thrust bearing, and smaller needle bearing for the drive shaft in there. I was thinking of heat then driving down from the top with a brass rod.

I would like to save the big pinion gear bearing from my donor, know the thrust will drop out, and then if I have too buy a new needle bearing if it is sacrificed in the removal–opinions on success?

Last question. If the entire lower unit si a lost cause I have a donor from an early 60’s gale 25–the water pump is different of course as it is a non thermostat motor but if I change the pump housing will it work? EDIT I compared the non thermostat lowers to the super quiet, No it will not work as it does not have the same cooling passages.

Sorry for the long list of questions. Hope someone can learn from my mistake and take the extra steps to double check. Of course, I am going back into my 56 due to the spaghetti leak and I hope the bearing is in there.

Thanks,

Allen

[cannuck]

One of the things I have found after about resealing almost 10 of these lower halves is not only all what is suggested here which is correct but— clean the crap out of the groove and spray final with carb cleaner or acetone . You cant be clean enough with an anaerobic adhesive that 847 is . Last you must coat all the screws with 847 and make sure on that little piece that extends after case prior too, give it an extra dab both sides By the way mine don’t leak so far with this procedure — Good luck just food for thought

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