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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 13581
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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Model 33M777 0116g1 Engine has gh crank pressure, oil comes

Customer Question

Model 33M777 0116g1
Engine has high crank pressure, oil comes back out through fuel pump line. My thoughts either crank case ventilation problem or possible broken piston ring. It started doing this all of sudden and seems the problem once the engine gets up to operating temp.
Bob White
Submitted: 1 year ago.
Category: Small Engine
Expert:  JohnF2015 replied 1 year ago.

Hi, Bob my name is ***** ***** I will be assisting you.

Can you do a compression check and let me know what the compression is? Can you do a cylinder leak down test on the engine? This could be as simple as a blown head gasket.

Customer: replied 1 year ago.
John I was able to do a compression test, The best pressure I was able to get was 65psi but I do the tests 3 other times and could only get 50 to 55psi each time. I am not sure how to do a leak down test. Bob
Expert:  JohnF2015 replied 1 year ago.

It does sound like you have a compression problem, these numbers are low for what it should have. I would suggest removing the cylinder head and take a look at the head gasket, I believe that you most likely have a blown gasket this happens often on these engines. It's not like the older engines, you won't hear that hissing sound when the gasket blows, they tend to blow between the oil drain back passage and the cylinder not externally. If you had a cylinder leak down tester you could perform a leak down test and be more positive about where your problem is but since you don't have one I would check the head gasket.