water in engine oil

[trichardson]

I have a Hunter 430 with a 50hp Volvo engine. A couple of weeks ago I came up with water in my engine oil. I pumped out the oil (milky color), put in fresh oil, ran the engine just a few minutes, then pumped it out again. I did this three times. Then ran the engine about 20 minutes. The engine runs fine, revs up, holds pressure, does not overheat. No missing, no fluttering. I checked it again--still milky.

There is no coolant smell and no color--just milky oil. I have pulled the water pump and it shows no sign of leaking past the seals.

I have checked the anti-syphon valve (vacuum valve). I have also changed out the exhaust elbow and the exhaust hose to the muffler.

The fresh water enters the thru-hull, goes through the transmission cooler, through the water pump, then through the anti-syphon loop, through the heat exchanger, and into the exhaust elbow. There is no oil cooler even though the manual says it is there. I assume that they changed the design at some point, and eliminated it.

Some how sea water is getting into the engine while it is running. But the water pump is the only place that can be happening, but it is fine.

I am at my wits end. Any ideas?:cussing:

Tom Richardson

 

[heritage]

Are you sure it is not coolant in the oil?? It wouldn't take much to give it the milky look and I don't think that you could smell it. I can't see any way that sea water could get into the engine oil.

 

[trichardson]

When I say it is milky, I don't mean cloudy or frothy. It looks like a vanalia milk shake. I forgot to mention that I also took the heat exchanger apart and pulled the tubes. I did find some old impeller fragments in the exchanger, and a torn rubber seal, but it was not restricting water flow, well, not a lot. I guess that the next step is to open up the heads and check the gasket. I was hoping I wouldn't have to do that.

Tom

 

[Rich Stidger]

Tom,

I have the same engine in my h40.5. Are you sure that it is seawater and not coolant? I doubt that you would see any color or detect any smell. Is the coolant overflow tank stable or is it dropping? On my MD22L-B the raw water pump is belt driven so it cannot leak into the engine. The transmission is completely separate so I don't think that is a source either. The exhaust elbow if defective could let water back into the cylinders, but not into the oil. The exhaust hose is too far downstream and cannot let water into the oil. The coolant water pump is also belt driven and I don't think there is any possibility of it allowing water into the oil.

Of the parts you mentioned I think the only possibility is the heat exchanger. But I think a more likely source could be the head gasket with a leak between the fresh water coolant and the oil galleys.

There are others on this board that are way smarter than me on this stuff. Give them a chance to chime in.

A couple of questions- Immediately after you ran the engine for 20 minutes, did you have water? Or did the water appear the next time you ran the engine? If the water does not appear immediately it could be as the engine cools it sucks in water thus you don't see the water until the next running. Do you see any bubbles in the coolant overflow tank? That would be an indicator of a bad head gasket.

 

[sailorjoel96]

I would check the antifreeze level. If that is ok then it's time to look at removing the head.

 

[Mariner356]

It could be somewhere in your heat exchanger. Sounds like you need to be in there anyway to get the impeller pieces out. Too bad you don't have a Yanmar as Mack Boring has really good training sessions for Yanmar owners to learn all aspects of the engine. I'd call Volvo and share what you've found and done. I'm sure they'd be able to quickly help you zero in closer to what to do next.

 

[trichardson]

There is no loss or gain in the coolant level, no oil migration into the coolant overflow tank, no bubbles. The oil appeared immediately after running for 20 minutes. The engine ran smooth as silk, easy to start. I immediately suspected the exhaust elbow because the old one was looking suspect. I obtained a new one from Volvo, ($450.00) and replaced it first thing. No luck.

My sea water pump is engine driven, but it looks ok.

By the way, I'm not doing this by myself. I have a good diesel mechanic working with me and he is just as baffled as I am. Our next option is to check the head gasket.

Tom

 

[Benny17441]

Sounds like a fouled cylinder head gasket. It has to be engine coolant and not sea water. It does not take much to emulsify the oil.

 

[centerline]

you should probably check the seals in your raw water pump.... im not sure of the configuration of that engine, but volvo liked to run the raw water pump off of some point in the timing chain/gear circuit.... and with that, as soon as you loose a drive shaft seal in the raw water pump, it pumps water into your crank case....... there are usually two or more seals to prevent this from happening, and a weep hole as well to take any seepage that may get past a seal, but i have seen the weep hole plugged up and the seals cant hold the pressure.... so, after any repair, insure you have no obstructions on the water flow and causing excessive water pressure, that in turn pushes water past a normally good seal... good luck

 

[Bill Roosa]

You can check for an anti leak using a pressure tester. Attache to the "radiator cap" and pump it up. If it holds pressure then the fresh water system is not leaking.
Alternately you can get clean oil in and leave the cap off (no pressure to push anti into the oil) and see if you still get water in the oil.
I'd spend the money on the pressure tester as it provides a positive indication. The "check the oil after running without the radiator cap method may not positively identify if anti is getting into the engine if it is really salt water....

 

[trichardson]

That's a good idea. I will try it tomorrow and let you know

Tom