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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10896
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I have a 95 Evinrude 40 hp 2 cycle outboard, the top

Customer Question

I have a 95 Evinrude 40 hp 2 cycle outboard, the top cylinder has a compression of 120 unfortunately cylinder #2 has a reading of 0.
A. What can cause this?
B. How do I start trouble shooting?
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. My name is Tan.

Since you have zero compression the first thing you need to do is remove the cylinder head and inspect the cylinder and piston. Usually when you have zero compression you have a burned piston, broken rings or damaged cylinder walls. The only repair for a case like this is to remove power head, disassemble and replace bad piston, rings and have the cylinder bored oversize.

What can cause this is water in the cylinder from blown head gasket, lean fuel condition from clogged carb or ring failure due to carbon build up in the rings on the piston.

Post a pic of the cylinder and piston after removal of the cylinder head and I can be more specific as to the cause oif the damage.

Customer: replied 1 year ago.
It sat for about 4 years doing nothing. I did fog oil it but not on the initial start attempt. Thinking its rings.I willsend a pic.
Expert:  Tan replied 1 year ago.

Ok hopefully you have just a bad gasket.

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