Water in engine oil.

[Ike]

Checked my engine today for the first time since I put the boat in the water at the beginning of June. The oil is milky. Obviously water is getting in somewhere. Did not have this problem last year or at the beginning of this year. The engine is a Mercruiser 165 (GM 250) in line six. It is 42 years old. The only thing on the engine that hasn't been replaced is the block (and internals) and the head. It is raw water cooled. No heat exchanger. All new exhaust manifold and exhaust/cooling system parts. All bellows and gaskets on sterndrive and so on. It is only used in fresh water. And, the engine runs very well. Reaches max rpm at WOT and does 30-35 mph.

Anyway here is my plan.

remove old oil and replace.
replace oil filter.
remove plugs one at a time, look for water, and crank to see if there is water in the cylinders.
check compression on each cylinder
run engine until it gets up to normal temp and run it for ten minutes or more.
drain and change oil and filter again
run engine
check oil for water.

I suspect a leaking head gasket (had that problem with another engine) but no white smoke in exhaust.

Worst scenario, cracked head or block.

Have I forgotten anything I should check or left out a step?
Any other suggestions, advice?

 

[Gary Hill]

Your thinking is correct but, pull all plugs, change that oil and filter, then with the plugs out spray some oil like WD40 in each cylinder and spin the motor with the starter. You need to start mitagating the risk of rust right away.

Good Luck.

 

[CliffA]

I suspect a leaking head gasket (had that problem with another engine) but no white smoke in exhaust.

a head gasket can fail in different ways.....it can fail and allow combustion gases to enter into water passages causing an overheating problem.....it can fail and allow cooling water to bleed into an oil passage....this will produce the 'milky' appearance in the engine oil.....it can fail and allow water to seep into a combustion chamber....this will produce the 'white smoke' you mentioned.....

cliff

 

[scoflaw]

a head gasket can fail in different ways.....it can fail and allow cooling water to bleed into an oil passage....this will produce the 'milky' appearance in the engine oil.....

cliff

Highly unlikely, seeing there are no oil passages in the head , and there is minimal pressure in the cooling system to blow out the gasket and make its way into the valley.

 

[CliffA]

Highly unlikely, seeing there are no oil passages in the head , and there is minimal pressure in the cooling system to blow out the gasket and make its way into the valley.

agreed but if the gasket failed and allowed the water passages to be pressurized with combustion gases the water could be forced to flow into unwanted places.....i have seen the water (coolant) bubble inside of the overflow tank on cars when the head gasket failed and pressurized the coolant system with super heated combustion gases....

cliff

 

[Ike]

Thanks, all good advice. I will let you know what I come up with.

 

[scoflaw]

agreed but if the gasket failed and allowed the water passages to be pressurized with combustion gases the water could be forced to flow into unwanted places.....i have seen the water (coolant) bubble inside of the overflow tank on cars when the head gasket failed and pressurized the coolant system with super heated combustion gases....

cliff

Totally agree with that, OP has open cooling and nothing to get pressurized, but seeing his boat is 40 plus years old who knows what the gasket looks like.

 

[CliffA]

Totally agree with that, OP has open cooling and nothing to get pressurized,

good point....

 

[OldSkool]

Check out this thread: http://clubsearay.com/showthread.ph...boat-water-in-oil-How-to-identify-issue/page2
It's the same issue you are having with a very not so good result.

 

[Ike]

Changed oil and filter. Ran engine for about 15 minutes.
Changed oil and filter again. Oil is still slightly milky but clear.
There is a small amount of water coming out of the manifold gasket just forward of the carb, right about where one of the bolts for the manifold is located. When the engine heats up the leak stops (at least on the outside). I checked the torque on the bolts and two were not as tight as the others. There are no other visual leaks. There is no water in the cylinders so I am now thinking (and hoping) it is just the manifold gasket

checked plugs and compression
cylinder
1 dry plug looks good 125#
2 dry looks good 120#
3 slight amount of oil, no water, 120#
4 slight amount of oil, no water, 120#
5 dry looks good 120#
6 dry looks good 120#

The engine runs well. However, it does not seem to be warming up to normal operating temps. I shot it with a infrared heat gun and temp was about 103 deg F, a lot cooler than it should be. I think the thermostat is stuck open.

 

[scoflaw]

Could be as simple as water in the oil from condensation, cause engine is running too cold

 

[Ike]

Could be. I estimate that there was almost a quart (maybe 3/4 of a quart) of water in it. It normally take 5 quarts and my oil reservoir that I use for changes holds six, and it was almost full.

 

[scoflaw]

Sounds like too much water to be condensation. Those intake manifolds do rust thru, might be a good place to start, or pressurize your cooling system and have a listen

 

[Ike]

Unlikely that it's a rust through. The manifold is only two years old and has maybe 20 hours on it. More likely it's the gasket. The manifold had to be taken off again last year because it was leaking, but not into the engine. So I think it loosened up over last fall and this summer and just needs to be re-gasketed. Only this time I'll let the pros do it.

 

[Ike]

Turned out to be a leaky gasket between the Riser and the exhaust manifold. All fixed. Cost $306.50 almost all labor. The gasket was $3.46.

 

[CliffA]

Glad it was nothing serious......good job troubleshooting the problem........

cliff

 

[OldSkool]

Ike,
Not quite sure how manifold and riser would cause water in the engine oil. Can you explain. Not trying to be a smarta$$ here but would truly like to know. I don't see where they can mix. Thanks

 

[Ike]

At the back end of the riser water is injected into the exhaust to cool and quiet the engine, but you do not want that water getting sucked back into the exhaust manifold. It then gets sucked into the engine through the exhaust valves, and can cause a lot of corrosion, dilution of oil, excess wear, and a condition called hydrolock, in which the engine essentially freezes up. The gasket not only seals the connection between the exhaust manifold and the riser, it keeps water from getting into the exhaust manifold. The manifold has a cooling water jacket and so does the riser. There is an opening that allows water to flow from the manifold water jacket into the riser water jacket. However if the gasket leaks it leaks water into the exhaust at the end of the manifold and start of the riser. That water gets sucked into the exhaust manifold. look here. http://blog.boats.com/2011/08/hydro-lock-engine-won%E2%80%99t-start/#.U-mY7GPLNbI

 

[Ike]

Leaking Gaskets The risers bolt to the exhaust manifold, and because the two parts expand and contract at different rates, it's hard to maintain a constant gasket seal. If water is leaking to the outside, it is also leaking to the inside. Count on it. Address the situation IMMEDIATELY. This may not wreck your engine, but salt water under the riser gasket will corrode the gasket surface on the exhaust manifold. A gasket cannot seal to an eroded surface. Once this happens, no gasket will ever seal again and the manifold has to be replaced. If you thought risers were expensive, wait till you see the cost of manifolds.

from http://www.yachtsurvey.com/exhaust_risers.htm