Mercruiser M-R Outdrive ??

[okieguy10]

Hey guys I have a 79 Galaxy with the 165 Inline 6 engine and Mercruiser outdrive. Getting it ready for the summer I changed the water impeller and reinstalled on boat. Ran it on muffs and checked outdrive afterwards. The oil is milky. Did some research on here and found that if seals are good it should hold 20 psi of pressure. A buddy has a tester for this and brought it over. Pressurized it up and it held 20 psi for at least 10 minutes while we bs about this and that. What, if anything, else could be allowing water in. After the 10 minute the first time I repositioned the prop and did it again for about 5 minutes and it held.
Thanks for any help

 

[Don S]

Re: Mercruiser M-R Outdrive ??

Drain the gear lube first, then do the pressure test. Only go to 15 psi, not 20.
Did you pull the outdrive off and look for water in the bellows? The input shaft seal is only a single lip seal, and works to keep oil in, not water out. The bellows will allow water into an area that is suppoed to be dry at all times.

 

[okieguy10]

Re: Mercruiser M-R Outdrive ??

Gear oil was drained when I saw it was milky and before the pressure test was done. Over the weekend I pulled the outdrive back off again just to check the bellows and all was dry in there.

 

[ziggy]

Re: Mercruiser M-R Outdrive ??

What, if anything, else could be allowing water in.

2, or no gaskets on the drain (or vent) screw might not show up during a pressure test because you had to screw the tester into the drain (or vent) hole. the tester might have sealed, the screw may not have.. just a thought anyways.

 

[okieguy10]

Re: Mercruiser M-R Outdrive ??

I have new orings for them that I have just now put on, but I have been running it on the muffs not in the lake. Would it make a difference on the muffs?

 

[frank246]

Re: Mercruiser M-R Outdrive ??

Did you replace the quad O ring on the oil passage in between the two case halves after you did the impeller?

 

[Don S]

Re: Mercruiser M-R Outdrive ??

Are you saying that when you changed the impeller the oil was OK, but when you ran it on muffs you got water in it???
You did changed the gear lube when you changed the impeller didn't you?

 

[okieguy10]

Re: Mercruiser M-R Outdrive ??

Yes the o-ring for the passage was changed and some perfect seal was put on it also.
Yes the oil was ok when I drained it for the impeller change. Put outdrive back together installed it on boat ran it, next day went out pulled lower filler screw on outdrive to check oil and was milky. Drained oil, pressure tested, filled with oil again, ran it up. To see if it was making oil or if level had changed I pulled the top cap. Level was right at the bottom of the vent hole so it is not making any. But oil was milky colored again. That's why I am extremely baffled by this.

 

[JustJason]

Re: Mercruiser M-R Outdrive ??

Pull the drive off and set it up in some kind of wooden rig. Pressure test to 15psi only, while it's pressurized and in neutral, spin the input shaft counter clockwise and see if pressure drops. Spin the propshaft in both directions. Leave the gauge hooked up overnight and see if it drops below 10.

 

[okieguy10]

Re: Mercruiser M-R Outdrive ??

Ok. Just something I have been wondering is, water is somehow in there making the oil milky thats a given but wouldn't the level be rising of the oil? I suppose it could be leaking out whatever way it is coming in. Could there be nooks and crannies in there that condensate from the temp swings over the winter can hide? How much water would make the oil milky?
Thanks for all the help and ideas so far.