Mercruiser taking on water & oil leak

[weslacey]

I went to take my 1978 Caravelle with a I/O mercruiser 165 out this weekend, and the first thing i noticed was while it was on the trailer out of the water, there was a small puddle of oil leaking out of where the plug goes (plug was out). Closer inspection led me to believe that this was gear oil from the lower unit. The trim was all the way up, but i can't imagine how it would leak into the engine compartment and out the drain plug hole without the motor running and that oil being thrown around. Well after checking oil levels i put it in the water anyways, and noticed that while beached, it was taking on water. I've inspected the u-joint bellows and cannot see/feel any holes. I do know that the exhaust bellows has a hole in it, but that shouldn't be it. Lower unit oil is milky too. The only thing i can come up with is a hole in the u-joint bellows that i can't see. I serviced L/U at the beginning of the season and changed the o-rings and gasket. So whadda ya think????

 

[rodbolt]

Re: Mercruiser taking on water & oil leak

I think ya now need a bellows, a set of ujoints, a gimbal bearing and a drive yoke and seal assy in the upper at a minimum. ya waited till water got in the bellows and the yoke rusted causing the seal to fail allowing the oil in the upper drive to leak into the boat Via the gimbal bearing when tilted. its common. while your in there see if the quad ring for the drive is still in place and one piece and inspect the seals in the exhaust cavity for the upper shift shaft. they tend to fail.goes back to why drive bellows replacement at 3 year intravels is always reccomended. if kept dry the assy usually runs a long time. a lube oil monitor kit is also reccomended.

 

[weslacey]

Re: Mercruiser taking on water & oil leak

The u-joints and bellows were replaced 2 years ago, and both looked fine when i had everything off at the beginning of the season. Oh well, the joys of owning a boat! Thanks.