Mystery - Water in Oil in Volvo DP-SM Drive

posloke123

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I have a 99 Cobalt with twin Volvo 5.7Gsi and DP-SM drives. I pulled the boat to winterize and do drive maintenance (and some bottom paint touch up). I used muffs to cool the engines while I got them hot enough to change the oil (a few weeks ago). I pulled the drives off this weekend and changed the drive oil. When I pulled the drain plug on the starboard drive about 10-15 ounces of clear clean water came out (our lake water is green tinted, but clean). Then the oil came out. There was no emulsion and the oil and water were clearly separated, so the water was almost certainly not in there when the drive was turning (running in the lake). My guess is that somehow when I ran the water to the muffs it leaked into the drive in the couple of minutes before I started the engines. I assume there would be about 40 psi water pressure and that might have passed through the seal on the freshwater feed pipe between the upper and lower units. But I would also assume any leakage would just run out the exhaust channel since the fresh water pipe appears to pass through it. I guess it's possible it could have leaked into the bearing retainer but that seems like a long shot.

I pressure tested and vacuum tested the drive and it passed (vacuum at 15 in - lost 1/2 in in 5 minutes).

Any ideas how I might have gotten clean fresh water into the oil without any emulsion? And of course, what to do about it.
 

GA_Boater

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Welcome with your 1st post.

Two weeks is long enough for the emulsion to settle so the water drains first. It's lake water in the drive regardless of the color, the algae died.

When you pressure tested, was the prop shaft, drive shaft and shift shaft rotated while under pressure?
 

posloke123

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Yep. The input shaft, shifter, and the prop shafts were rotated while pressure and vacuum testing. And the oil was drained out first too.
 

Grub54891

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Some can be a bugger to find the leak. We have one on the shop now, it passes all pressure and vacuum tests. I think its temperature related, when warmed up well, then shut down, it pulls water in from the vacuum it creates when cooling down. But with the remote reservoir , I would think that there would be little vacume...not sure, bit the oil was milky, and re-sealed last winter.
 

BRICH1260

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I`m chasing the same demon. My drive oil was a little milky when drained this year. I have pressure and vacuumed tested the unit several times and have not been able to locate the source. Mine will hold pressure and vacuum for hours without loss, even with all moving parts being rotated. Same thing happened last year and I replaced the shift seal, thinking that was the culprit, apparently not. May have to replace the prop shaft seals next. I`m running out of possibilities.

Back to the OP problem. My guess is that the water has been in there for some time and not a result of running the engine on the muffs.
 

bruceb58

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Any ideas how I might have gotten clean fresh water into the oil without any emulsion? And of course, what to do about it.
Do you replace the o-rings on all the plugs EVERY time you change the gear oil?
 

posloke123

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It would seem that to get as much water in the drive as I had - probably 10-15 ounces came out - it would have to be a pretty substantial leak, or be leaking for quite some time. I put about 60-70 hours on it this summer and I run it pretty hard (I like those 50+ MPH spurts - watching the gas gauge drop in real-time, cruising at 26-30 all the time, and just took at 112 mile trip at 28 MPH at the end of the season [stopping for lunch]). If it had that much water in there for very long I would expect the drive to be trashed, or these Volvos are tougher than nails.
 

BRICH1260

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I know most outdrive specific oil ( Volvo and Amsoil) are designed to carry up to a10% water intrusion solution. I`m sure glad I didn't skimp on my outdrive oil. Posloke, your`s is a bit of a puzzle, I have never experienced or heard of anyone else have a total separation, usually it`s a milky solution.
 

posloke123

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I know most outdrive specific oil ( Volvo and Amsoil) are designed to carry up to a10% water intrusion solution. I`m sure glad I didn't skimp on my outdrive oil. Posloke, your`s is a bit of a puzzle, I have never experienced or heard of anyone else have a total separation, usually it`s a milky solution.


Glad I used Amsoil too.
 

bruceb58

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No water in the bellows right? If you had a substantial tear, you may not see much in there but you would definitely see rust.
 

muc

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I've had more than a few drives over the years that pass vacuum and pressure tests but still had milky lube. First always make sure it's not the drain plugs. --- real sure ---- then disassemble the drive and pay close attention to the area between the two seals, when you find the one without grease between them. That's the leaker.
Yes, Volvo drives tolerate water much better then MerCruiser's.
Good marine drive lube will hold some water in suspension and stay "milky" for awhile, not so good drive lube separates pretty quickly.
 

posloke123

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Thanks for all the advice. I guess the water had been in there a while but it looks like the drive is probably okay. I'm going to replace the shifter seal this week and have the local boat shop replace the shaft seals. They'll do it cheaper than I can buy the special tools.
 

posloke123

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Follow up question. After letting the drive drain into a pan for about a week, I filled it with 3 quarts of 0W-20 motor oil to flush out any remaining water. I worked the shafts to stir it up. I then pulled the drain plug and let it drain for a week to let it all get out.

After that I did a pressure test, which it passed (15 pounds, no loss in 5 minutes). I did a vacuum test and it wouldn't hold vacuum. It was losing about 5 inches in 5 minutes.

I got an estimate to do the shaft seals - $275, which didn't sound bad (and I don't have to buy any special tools). I decided to replace the shifter seal first though.

When I pulled the shifter mechanism, the clevis pin was bent. I noticed last year that when I shifted that drive sometimes it would 'thunk, thunk, thunk' and then pop into gear. The bent pin explains that (how the pin got bent is anyone's guess - probably shifting into gear above idle, I'd guess).

Anyway, my theory (hopefully better than the first one) is that the bent pin allowed the shifter plunger to come out just a little too far and perhaps water leaked in there. The plunger has a ring machined into it that is smaller than the seal area and maybe it came out far enough to leak there.

I put it back together and it passed both the pressure and vacuum test - held both with no loss for over an hour (periodically moving the shifter and turning the prop shafts).

Do you think it's fixed or should I have the prop shaft seals done too? The lower unit is only 2 years old. Thanks for all your help.
 

BRICH1260

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As it seems to be passing tests now, I'd leave it as it is. Maybe drain a bit of oil next season and check the oils condition.
 
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