Frozen engine head, 40hp 4-stroke

[Ricky_richer]

I recently bought a broken Mercury 40hp 4-stroke from 1999. The former owner had it outside when it was freezing, so now the cooling water gets into the engine oil. The engine runs fine, but water instantly mix with the oil. When the engine froze it was tilted up. Anyone have an idea where the damage has been done? I have lifted the powerhead, but cannot see anything suspicious.

The engine has very few hours on it, so it would be great if it would be fixable.

 

[joeanna]

it could be just bad seals now, or possibly a crack anywhere inside the engine/head......

 

[Ricky_richer]

Is there a procedure to find the leak of this kind?
Can I connect the water inlet in the head to compressed air, and then listen for a leak? Should thermostat be removed if I try that?

 

[QBhoy]

Unusual for water to remain in the block and head. They are usually designed to allow the water to drain out the whole unit, when not running. Exception might be the lower gearcase...if the engine is left tilted up.

 

[Ricky_richer]

I see, but that can not cause water mixing with engine oil.
Is it possible that I have the leak in the rigg? Water pass through close to the oil "tank".

 

[Ricky_richer]

I see, but that can not cause water mixing with engine oil.
Is it possible that I have the leak in the rigg? Water pass through close to the oil "tank".

I just realize that the water goes from the gearcase to the powerhead, through a pipe on the outside of the rig. So if water gets into the oil it must happen in the powerhead. Where should I start?
Compression test? Should have done that before removing the powerhead I guess.
Remove head to check head gasket?
Remove baffle plate?

 

[Ricky_richer]

I noticed some water coming out from the pipe in the block that leads to the oil pump. I took to oil pump of and found that the piece that connects the pump to the cam shaft is somewhat broken. I think the pump is still turning with the cam. But I cannot see how this can have anything to do with water in oil?
The only thing left to do is take head of, or what do you guys think? There isn’t much water passing through the block from what I can see. And all the heat is produced in head and exhaust baffle. So head or head gasket is suspicious in my eyes...

 

[GA_Boater]

Compression test before you tear it apart any further.

Put the oil pump back on, even with broken drive. Wonder how that was busted?

What is the serial number? For Mercs that is more important than the year of the motor.

 

[Ricky_richer]

I cannot do a compression test with the head on the bench. But I did a cylinder leak down test. All cylinder looks really good, only about 2% leakage, and that little leakage was down in the cylinders pass the rings. What I understand is fully normal. The engine is also running just fine. But water ends up in the oil pretty fast. Where can it leak through?
Your right about the oil pump, strange but nothing to do with this leakage.
The serial number on the sticker on the rig is just gone, cannot make a single number out??

 

[goldstem]

on most four strokes, the cooling water is pumped up through the oil pan to the powerhead. if there are any failed gaskets in there, water will get pumped right into the oil. this happened to me on a suzuki, common with that particular motor, less common on mercs,

 

[Marine Services of Las Vegas]

The oil pump shaft was keyed wrong, also what was your working pressure (psi) while doing leak down test?

 

[Ricky_richer]

Then the pump was mounted wrong from factory. Engine has never been worked on after that, paint on all screws.
I used about 100psi when doing the test; I have never seen an engine with such good values on a leek down test. And since engine is running fine there's no leak in or out of cylinders.
I'm really lost here... Removing head seems like a long shot. Can water really leak past the gasket and into an oil canal there?