Water in Oil - Not Same Old Suspects

[dthomas95]

A couple weeks ago I changed my oil and found water in it - light chocolate brown. Called in the local mechanic who did another oil change, did a block pressure check and compression check on all cylinders, as well as a tune-up. Gave it a clean bill of health and figured it was something fluky like backwash through the exhaust system.

Took the boat out and since I was running downwind in light air, I decided to run the engine. Ran for about 30 minutes and started losing power. Shut the engine down, sailed back to port. Had to tack upwind, so it took about 45 min. to an hour. Started the engine and it ran fine again for about another 15-20 minutes before acting up again. Was able to limp back to the dock under reduced power.

Mechanic came back, found more water in the oil - so much for a fluke. However, he's now not sure what is the problem. Due to running OK when cool and loss of power when hot, he's thinking something is expanding or "opening up" when hot allowing water into the oil. He's thinking he may have to pull the engine and open it up to visually inspect.

Before he goes to this amount of work and expense, does anyone here have any suggestions what the problem might be?

[hanleyclifford]

Check water pump for bad combination of plugged drain hole and faulty shaft seals.

[dthomas95]

Wouldn't this cause the engine to overheat? It did not.
Would this explain the rough running and loss of power?

I have forwarded your suggestion to the mechanic. I'm just thinking ahead and trying to acquire some knowledge along the way.

[mike7a10]

Hi DThomas...

I had water getting in my oil last year and it turned out to be the water pump. There are weep holes on the pump and if you see ANY water coming from the weep hole I suggest you immediately remove it and replace it.

I ended up with a bent connecting piston rod and had to do a complete rebuild (which I needed to do anyway to a 35 year old engine).

My engine did not overheat either. With time a water pump leak becomes worse as the seals let go. So if you are noticing that the water is coming in more quickly then it is time to check that water pump!

Good luck!

Mike

S/V Plan Sea
Punta Gorda, FL

[hanleyclifford]

The bad seals and water leak would not cause rough running or overheating unless a significant amount of water were lost and not replaced.

[chrish123]

Not necessarily true. This is exactly what happened to me. The pump seals gave out, a bit of water got in the oil, turned it to chocolate brown and grey and oil lost its viscosity. You can feel the difference in your fingers even. Aparently its the detergents that react most with water leading to breakdown and its doesnt take much either. See my previous post on this matter.

Best of luck. I would change out the pump ASAP and followed by the recommended number of oil changes.

Best regards

/ch

[hanleyclifford]

Chrish123 - Could you please explain to me how water in the oil causes an engine to run rough?

[dthomas95]

Does anyone know where I can get a photo of the water pump that clearly shows the weep holes. Not saying this is or is not the problem, just something else to check. I don't have the Owner's manual in my possession - it's on the boat so I won't be able to check for a photo there until this weekend.

[roadnsky]

Does anyone know where I can get a photo of the water pump that clearly shows the weep holes. Not saying this is or is not the problem, just something else to check. I don't have the Owner's manual in my possession - it's on the boat so I won't be able to check for a photo there until this weekend.

Which pump?
I've got lots of them but it's the MMI 502 pump.

You can take pics of yours if you want.
Just use a mirror.

[edwardc]

Chrish123 - Could you please explain to me how water in the oil causes an engine to run rough?

If you have a pcv valve installed, it channels the crankcase blowby back into the carb. With water in the oil, once the engine heats up, the water begins to turn to steam. The pcv valve directs this steam into the carb too. This is like dumping water into the intake. The engine runs rough and looses power.

[hanleyclifford]

Edwardc - Thanks for the comeback. I can relate to the part about losing power, but I still don't get the rough running part. My experience has been that moist air actually helps an engine run. Of course we could be talking about a question of degree here. Regards, Hanley