Water in oil; good compression; 2 white plugs

[bullsey398]

Hello,
I have a 2000 Moomba Boomerang (low profile, direct drive ski boat), with a 350 Indmar conversion (carbureted). Engine has 475 hours on it. I am the 2nd owner, so I don't know all of the history, but it has been winterized properly since I've owned it.

Problem:

I have water in the oil (changed several times), but the engine seems to run fine, (perhaps a little rough at times... but not bad.).

The oil level increases about 1 qt... after running for several hours.

Tests/ observations so far:

I've checked compression and all cylinders are between 180 - 185 psi.

2 spark plugs (front 2 on starboard side) appear lighter (white-ish, but clean) than the others. All others look fine (tan and clean).

The exhaust flap on the same side (starboard) appears to not seal well and has signs of rodents chewing on it.

Questions:

- Does the water in oil sound like an engine problem... or possibly back flow through the exhaust?

- Is there a test I can perform to help ID the cause of the water in oil?

- If I continue to change the oil frequently... will I risk damage to the engine if I continue to run until fall?

Thanks for your help!

Greg

 

[alldodge]

compression and all cylinders are between 180 - 185 psi.

That's pretty high for a 350, should be closer to 150 psi.

Getting water in the motor is bad and will destroy it. With the two plugs being whiter then the rest my first guess is you have a blown head gasket. That said I don't see getting the same compression on those two cylinders as the rest.

Are you checking the compression cold or warm?

You should have a transmission cooler, do you also have an oil cooler?

 

[Bondo]

Questions:

- Does the water in oil sound like an engine problem... or possibly back flow through the exhaust?

- Is there a test I can perform to help ID the cause of the water in oil?

- If I continue to change the oil frequently... will I risk damage to the engine if I continue to run until fall?

Ayuh,.... Welcome Aboard Greg,....

The only way the water can get into the oil from the exhaust, is past the rings,....
Yer motor would need bad rings, 'n it can only happen when the motor ain't runnin',...
If yer motor is addin' water to the oil runnin',....
Odds are a cracked block or head,....
A bad head gasket is probably possible, but highly unlikely,....

The "Test", is to isolate the block, from the rest of the coolin' system, drain it of water, then pressurize it to 'bout 15 psi, 'n Listen,.....
Pull the spark plugs before ya do the test, if it's leakin' into a cylinder, ya oughta be able to hear it through the spark plug hole,....
Ditto through the carb, or exhaust, or oil fill, valve cover, etc....

'n,... Ayuh, of course ya Risk more damage,...
Whatever's goin' bad, could decide to Really Go Bad,....
It's yer boat, 'n it's up to you whether ya roll the dice, or just fix it now,....

Now my questions,.... How do you winterize,..??
How many hours has it run this season,..??
Has it had water in the oil all this season,..??

 

[bullsey398]

Thanks guys!

AlDodge... I don't know what the compression should be... but since they were all very close... I figured they were correct. I ran the test warm.
I do have a trans cooler, but no add'l oil cooler... good thought though!

Bondo --- Yeah... I was hoping it maybe as simple as a head gasket... but I would think they would be more likely to fail where this is higher pressure from the cylinders... not between water / oil passages, right? I'm also thinking the oil pressure would be higher than the water pressure, so water shouldn't be entering oil if the gasket was bad, right?

Your questions:
- I winterize by draining all water lines and block and header cocks... then pump in antifreeze via the raw water pump until it comes out the exhaust... then drain again.

- probably only 10 hrs this season (got a late start this year!)

- This is the kicker... oil in water was observed last year when I purchased the boat. I drained and refilled twice and no water after running again. I assumed that water had been sucked in through a seal when the bilge had high water in it... this was happening frequently due to a packing gland HEAVY leak by. I repacked the gland this year and have been very careful about draining the bilge before running... so now I think there is something else going on.

Is there a good write up on Iboats that describes how to isolate the cooling system on an inboard and perform the pressure test? That sounds like the next step unless you have any other suggestions?

Thanks again!

Greg

 

[jimmbo]

I was going to suggest the intake gaskets, but then I see you bought the boat(last year) with water in the oil(should have mentioned that in the first post, which was a bit misleading). Now I'm thinking cracked block

 

[Bondo]

Is there a good write up on Iboats that describes how to isolate the cooling system on an inboard and perform the pressure test?

Nope, not really, to many differences 'tween 'em all,......

The water comes into yer boat, somewhere, 'n goes to the raw water pump,....
From the raw water pump, it flows to the T-stat housin',... Cap it there, on the T-stat housin',....

The T-stat housin' feeds the circulatin' water pump, 'n probably 2 or 4 hoses to the exhaust manifolds,...
Cap off the hoses to the exhaust manifolds, at the T-stat housin',....

The block will have 2 drain plugs, 1 each side down low, 'bout middle of the block, just above the oil pan,...
Remove both drain plugs, 'n drain the block,....
Put 1 plug back in, don't matter which side, then plumb in compressed air with a pressure gauge in the other one,....

Pressurize to 15 psi, 'n Listen,....

 

[bullsey398]

Thanks Bondo... I'll give it a try!