2000 75HP Mercury with low compression on 1 Cylinder

[PISTONESAL]

Hello,

Would a bad head gasket cause one out of 3 cylinders to have low compression? I got 120psi on 2 and 60psi on cyinder 3. Also, should I still be able to start engine and stay running because mine wont. Any help would be appreciated. I already replaced fuel filter, rebuilt carbs and fuel pump. thanks

 

[flyingscott]

There is no head gasket on that motor. Take the exhaust cover off and look at the piston. More than likely you need a rebuild. It may not run if there is enough damage inside the motor.

 

[racerone]

Agreed , no head gasket on that motor.----Still hoping for an easy fix are you ??

 

[PISTONESAL]

What about the cylinder block cover gasket? Isnt that the gasket that seals for the water to go around the cylinders for cooling? Yes trying

 

[flyingscott]

That is only a water jacket nothing more. The block and head are cast as one unit on that motor. Ever hear the term blind bore?

 

[racerone]

There are NO GASKETS and no valves involved with the compression in the cylinder !!

 

[Scott Danforth]

at best you have a broken ring and ring land and no bore damage..... however most likely not.

 

[PISTONESAL]

But the entire power head will need removed to repair the broken piston ring? Even so, shouldn't I be able to start it and keep it running since the other 2 cylinders are ok? My engine won't start and when it does will cutoff within seconds...

 

[flyingscott]

Your engine is damaged!!!!! It may not run correctly the more you try to force it the worse it will get