MerCruiser 1, Lower Oil Seals

[Way2cool]

Hi guys,

I'm still messing with this 'acquired boat' fixing things that stop it from launching.. lot's of stuff in the works and on the bench.

On the Lower Unit, I need the oil seals replaced. The process seems pretty straight forward, (a) remove that HUGE nut the book calls 'Cover, gear housing' (b) slide out the 'bearing carrier'.. and work on replacing those seals on the workbench.

Well.. I cant get that 'Cover, gear housing' (NUT) to turn.. I've put about 200 ft.lbs against a counter-clockwise rotation and it wont budge..

So, should I give up and bring it to a shop.. or try something else?

 

[Bt Doctur]

Re: MerCruiser 1, Lower Oil Seals

That looks like is has a cutter seal already, why are you replacing them?

 

[Way2cool]

Re: MerCruiser 1, Lower Oil Seals

Well.. I passed a 24 hour pressure test.. no problem. .. and I'm leaking gear oil from behind that big 'ol nut somewhere. I'm also replacing all the seals in the 'shift shaft bushing assembly' as there's quite a bit of gear oil coming up from there as well.

Hmm.. could the shift shaft bushing be the ONLY problem? Would oil leaking from the shift shaft wind up coming out behind the big NUT on the lower?

 

[Bt Doctur]

Re: MerCruiser 1, Lower Oil Seals

There is an O ring for the carrier and 2 prop seals, thats it. oil leakage from that area can be caused by the shift shaft seal, the water pump base seals. oil flows downhill so , the upper seals,for the driveshaft, the shift shaft seal, and the water pump base seals.
Very limited areas for leaks. http://www.boatfix.com/merc/Servmanl/6/6covr3.pdf

 

[ktbarrentine]

Re: MerCruiser 1, Lower Oil Seals

My money is on your shift shaft seal leaking. I recommend doing a lower unit pressure test by itself and using a soap-bubble solution spary to test for seal leaks. All you need to do to this test is plug the oil passage port (with a rubber taper plug) and test from the bottom oil-add/drain port.

(yes.... oil from your shift shaft bushing, or the vertical shaft seals in the upper half can and will leak out of the prop area).

If at all possible avoid removing the prop seals.... and in your case (cant get the nut to turn), you are not alone. Most have to drill small holes at strategic locations and break that nut out.

 

[Way2cool]

Re: MerCruiser 1, Lower Oil Seals

Got it !!

Thanks guys.. I'll do the bottom only pressure test and see where that leads.
Hopefully I'll just have to rebuild the shift-shaft bushing and be done with it.

I'm soooo glad I checked with you guys before getting a longer cheater bar..

PS:
I have a complete water pump kit as well... hopefully that'll dis-spell any leaks from that area.