Mercruiser 4.0 problems

johcar2

Cadet
Joined
Jun 5, 2011
Messages
29
I finally got it to run with a new coil, points, etc., but once running I learned that there is water leaking from under the manifolds and cylinder #3 has low compression, like less than 50. With that, any clue as to what I will find when I get it apart? I'd like to be armed with the needed parts once I find out what the problems are.

As to the rest of the engine, compression on the other three cylinders is more than 135 lbs. While it will run on three cylinders, the plugs on the other three are very sooty. It shifts into forward and reverse without any problems. I will rev up past mid range, even on three cylinders. So I open to any info you can provide on what to expect, what to do, etc.

Thanks
John
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
Re: Mercruiser 4.0 problems

cracked exaust manifold or cracked block, you need to remove the manifold and see
 
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