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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10974
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I replace a 1995 5.7 merctuiser with a Jasper engine with the

Customer Question

I replace a 1995 5.7 merctuiser with a Jasper engine with the same block casting number. I have only had the boat out a few times (short trips). It developed excessive blow by. It is so bad it fills the boat with white smoke. Does this sound like a problem in the heads? I'm not sure what all will cause bad blow by.
Submitted: 2 years ago.
Category: Boat
Expert:  Tan replied 2 years ago.
Hello. My name is***** can be caused by valve guide seals in the heads. The oil leaks down past the valve guide seals dumping oil into the combustion chamber.Have you done a compression test yet to be sure you don't a ring issue? The engine isn't over heating is it?
Customer: replied 2 years ago.
Not over heating. Runs good, just get a lot of smoke from the valve covers. with the oil fill cap on it will pressurize the crank and smoke will come from under the valve covers.
Customer: replied 2 years ago.
have not checked compression
Expert:  Tan replied 2 years ago.
That kind of blow by is from poorly seated or bad rings. How did you run the engine for break in?
Customer: replied 2 years ago.
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Customer: replied 2 years ago.
If you have a better engine supplier, can you sent the contact info?
Expert:  Tan replied 2 years ago.
Here is the supplier I use and have had great success with them. Post back if you need further assistance. Please don't forget to positively rate me as that is the only way I get credit for helping you. Thank you.......Tan

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