1980 Merc 115 Low Compression in One Cylinder

[Bill Collector]

Engine has 3 rebuilt carbs, new water pump, new fuel pump, new plugs, and runs like champ. Has never let me down and is 100% fresh water. Did a compression test and I have 90 psi on all cylinders and 75 on one. Not good.

Is this indicative of a head gasket? Looking for info on how to diagnose.

Thanks!

Bill

 

[gbrowne9]

Re: 1980 Merc 115 Low Compression in One Cylinder

that motor does not have a head gasket, the pistons go in from the crank side. try doing a decarbon and recheck compression.

 

[Chris1956]

Re: 1980 Merc 115 Low Compression in One Cylinder

Get a new compression gauge. if those readings are accurate, that motor is pretty sick. I will bet your compresion readings are really more like 125 and 105. For a 32 year old motor, I think those are in spec. Do the decarbon and run it....

 

[a_jester65]

Re: 1980 Merc 115 Low Compression in One Cylinder

What is a decarbon?