Mercruiser 3.0 water in oil

[38special]

I bought a boat with engine today just for the 3.0 Mercruiser. The guy said it had over heated last year but that he had a head gasket put on and then used the boat about 5 or 6 times with no more over heating. I put a carb on it when i got home and hooked water to the lower out put. I had checked the oil when i was inspecting the bolck and manifold for cracks.

He said he had it winterized early fall last year. The oil was clean when i checked it. It started right up and sounded pretty smooth. The prop was spinning and would not stop no matter where i put the selector. I shut it off after a few minutes and checked the block again for cracks and leeks and found nothing then checked the oil. It was starting to get milky. Whats my next step? I did ask him if he had the head surfaced when the new head gasket was put on and he said no.

 

[Don S]

Re: Mercruiser 3.0 water in oil

Have you read this thread yet?
http://forums.iboats.com/showthread.php?t=369864

 

[Bondo]

Re: Mercruiser 3.0 water in oil

I shut it off after a few minutes and checked the block again for cracks and leeks and found nothing then checked the oil. It was starting to get milky. Whats my next step?

Ayuh,... Drain the block's cooling passages, isolate it,+ add Air...
It should hold 15psi...
If it Don't,... Listen for the leak,+ follow the sound...

 

[38special]

Re: Mercruiser 3.0 water in oil

Ayuh,... Drain the block's cooling passages, isolate it,+ add Air...
It should hold 15psi...
If it Don't,... Listen for the leak,+ follow the sound...

I did a compression test today and the number 3 cylinder leaks down pretty fast where as the other cylinders hold. No. 3 lost 5 psi in about 60 seconds repeatedly. I am going to pull all the plugs tomorrow and put 100 psi to no. 3 and see if i can find where it's going.

When i get that done i will follow your advice. I can live with sleeving a cylinder and hope at the worst that is my problem. I really hope it's not a crack on the inside of the block.

 

[38special]

Re: Mercruiser 3.0 water in oil

Have you read this thread yet?
http://forums.iboats.com/showthread.php?t=369864

I have now. Thanks. I'm pretty sure that bit of information did not make me feel better. Lol

 

[38special]

Re: Mercruiser 3.0 water in oil

I have tried several times to download the service manual with no luck. Other than the 4 bolts that bolt the engine down, electricle conections and the water inlet hose, is there anything else that has to be disconected to pull the engine? I have pulled the output drive already. Does the driveshaft bellows have to be disconected?

 

[38special]

Re: Mercruiser 3.0 water in oil

I got the engine out and torn down today. No visable cracks inside the block and none on the outside. What i did notice when breaking the head bolts loose was some were tight and some not near as tight.


After i removed the head i saw what looked like a new fel pro head gasket and after removing it the remains of another head gasket. Who ever changed the gasket did a poor job of cleaning the old gasket off.

Someone has sunk the valves in the head so new valves and seats will be needed. I will likely have it and the block surfaced and pressure checked.

 

[38special]

Re: Mercruiser 3.0 water in oil

One other thing i noticed was the rod in the number 1 cylinder and the rod in the no. 3 cylinder had way more side clearance than the other two rods. Are they sopposed to have more or do i have a problem?