rear oil leak

[Jim Booth]

We found the source of a persistent oil leak at the rear of the engine (not a pan gasket).

Is there a write up on replacing the rear oil seal? I have the Moyer book but it doesn't seem to deal directly with that. Basically, is it a matter of remove the prop shaft, output coupler and rear "plate", dig out the seal and reverse the process?

My boat came with two spare seals when we bought it about 15 yrs ago. I presume they are for the rear but maybe not. Both have part number CR USA 14875 embossed in them. One is in an old plastic bag marked 239919 from Universal Motors that looks used. The other is in a Chicago Rawhide box that looks new, though maybe it's too old and dried out to risk putting it in.

Thanks,
Jim

[Al Schober]

Jim,
You seem to have a handle on it. Remove bolts holding coupling to transmission, and slide the shaft and coupling aft. This will give you access to the big nut on the transmission shaft. There should be some locking tabs that you'll have to bend down. Socket and breaker bar to the the nut. Holding the flange from turning is the issue. Two options come to mind: a) buy/make the tool to hold the flange, or b) buy a new nut and just cut off the old one. Once the nut is off, the flange can be jacked off the transmission shaft using 3 bolts. This gives access to the aft plate carrying the seal - unbolt it, replace the seal, and reinstall. Again, the issue is tightening the nut. If you have the tool, no issue. I've used a strap wrench to hold the flange, and gotten it as tight as I could - haven't had an issue.
Hope this helps.

[roadnsky]

Is there a write up on replacing the rear oil seal?

Yep, attached here...

[Jim Booth]

Will an electric impact wrench get it off? I think I have the right size socket around here.

[marthur]

Will an electric impact wrench get it off?

Probably, but I didn't have room to use one when I did this job. I used an ordinary breaker bar (1/2 drive) and bought the tool from MMI which made holding the shaft a breeze.

Be prepared. Even though I emptied the oil, when I removed the coupling I still got enough to make a mess. Be ready with some rags or an oil absorbing sheet.

[Jim Booth]

I couldn't get it off with a breaker bar even after spraying with pblaster. So I bought the correct 6-point socket and my impact wrench took it off in a flash. Maybe the trip to buy the socket gave pblaster long enough time to work.

[sastanley]

Jim, I had the exact same experience...I think the impact part of the impact wrench is the key..it took me longer to run the extension cord than the impact wrench took to knock it loose, after several days of messing around with a pipe/socket/breaker bar.

My Indigo thread from back in the day has some info on rear seal replacement which I did during the whole shaft/log fiasco, but you have already accomplished the hard parts. I ruined the coupling trying to get it off too, but Moyer had one to me in short order!

[Jim Booth]

It's nice to know I'm not the only one taking days to accomplish a 5 minute job.

[sastanley]

It's nice to know I'm not the only one taking days to accomplish a 5 minute job.

I think mine was 3 weeks.

[Jim Booth]

Much cleaner

Thought I should update and thank you all. The boat has been in the water almost a week now and there is only a tiny amount of oil under the motor. It appears to be coming from behind the plate that the Facet fuel pump is attached to. There is no water leaking from the new MM water pump so I'm happy now. I'll tackle the remaining leak in the fall. Thanks again.