Another water in oil thread

[alexr254]

This is driving me crazy!!

1989 Mercruiser 470 engine. I have rebuilt these engines already a couple times, one engine i did is great with no issues, the second engine is getting water in the oil somehow which i cant figure out how...

At first i thought it was a bad head, so i took the head to a machine shop to have it pressure tested, it passed. The head gasket looks fine, i replaced anyway, still happens. Then we assumed it was a cracked block, i replace the block with another i know is in good shape. Still water in oil after another rebuild... I just ordered a new head to make sure the machinist was not wrong in his tests, which i beleive is very possible. Either way, i have a new head coming.
I am sure its not the cam seals since i just placed speedi sleeves on the cam shaft and put new seals, plus nothing is leaking from the weephole which i am sure is not clogged.

I just want this dam problem solved. What else can be the culprit here? Intake manifold? Exhaust manifold? Anything else possibly?
What tests should i do? Also keep in mind the water only starts fouling the oil after the engine heats up, if it runs for a few mnutes only the oil is clean, after a good 10-15 minutes or 5 minutes of high RPM idling, water is there in the oil again...

 

[Pete104]

Re: Another water in oil thread

Are you loosing anti-freeze?

 

[Exotic4x4]

Re: Another water in oil thread

Check your intake manifold...also when your doing your rebuilds are you having your blocks cranks and heads magnafluxed? (Checked for cracks)

 

[alexr254]

Yes it's from the closed cooling, I am using water while testing. Not a/f since I drain after each test.

Can anyone make sense for me how water can get into the oil from the intake or exhaust manifold, I am not seeing how they even get close to each other.

Unfortunately the machine shop in my town is not very sophisticated. And I don't know of any others that work on engine parts.

 

[Don S]

Re: Another water in oil thread

Probably from the cam seal, common problem on the 470s. The cam gets a groove in it and the seal will not hold water back.

 

[alexr254]

It's not the cam seal. I installed speedi sleeves and put on new seals. Also nothing is leaking out the weep hole.

 

[Don S]

Re: Another water in oil thread

Drain the cooling system, then pressure test it to see if it holds 15 psi. It has to be drained first.

 

[alexr254]

Ok after I do that and if pressure dosnt hold, which I am pretty sure it won't since I already know coolant is getting into the oil, then what? I feel it would just confirm what I already know and I am still scratching my head wondering what is causing it to happen.

 

[Don S]

Re: Another water in oil thread

Listen very carefully, maybe you can hear the leak.

 

[Bondo]

Re: Another water in oil thread

Ok after I do that and if pressure dosnt hold, which I am pretty sure it won't since I already know coolant is getting into the oil, then what? I feel it would just confirm what I already know and I am still scratching my head wondering what is causing it to happen.

Ayuh,... With the system drained, you'll hear the air escaping,...
Follow the Sound of the escaping air...

 

[alexr254]

Ok great, I will definitely goto autozone and rent that tester. Do I plug it into the heat exchanger where the closed cooling drain is? or is there another spot?

 

[Don S]

Re: Another water in oil thread

The tester is a standard radiator tester, just put it where your pressure cap is.

 

[alexr254]

Thanks I've never used one before. I will try it.

Although I'm pretty sure the leak is internal and something I won't be able to hear. We did closely inspect the engine while running, it is currently out of the boat on a engine stand.

I would still like to understand better how the intake an exhaust manifold can possibly foul the oil with coolant. Logically I don't see where or how they can.

 

[Don S]

Re: Another water in oil thread

I would still like to understand better how the intake an exhaust manifold can possibly foul the oil with coolant. Logically I don't see where or how they can.

Me too.