Mercruiser leg oil leak

NZ-Kevin

Petty Officer 3rd Class
Joined
Mar 2, 2010
Messages
96
Having got the engine running Ok (see my last thread) I took the boat out to do some fishing yesterday. Didn't go far, which was a good thing. When I took the bung out and drained water there was some oil in it. It didn't seem to have come from the engine, so I thought it must have been the drive. As the oil was brown I thought a seal had gone and water had got in and pushed the oil out somehow. So first thing this morning I drained the leg oil, expecting it to be half water. It took a long time to drain, and it was murky oil floating on water. I replaced the oil recently, and this is the first real use the boat has had.

I presume the seals on the drive shaft have gone, is it usual for oil to come into the boat when this happens? The water seems to have displaced the oil -but should there be an upper seal as well thst I need to replace?

The leg is the original 165hp one, serial number 4447730.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Mercruiser leg oil leak

You need to pull the outdrive off, check the bellows for water, drain the drive of gear lube (and water) and do a pressure test to find all the places that are leaking. If there is water in the bellows, that seal was never designed to keep water out of the drive, only oil in it. If there is water in the bellows, the input shaft yoke is probably rusty and destroying the seal like sand paper.
 
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