compression 1998 johnson 115

[awol1]

Four cylinders: O 125 O 80 <br /> O 125 O 125<br /><br />Is this a bad cylinder. Is there anything I can try to "fix this" before a rebuild. Can you rebuild just one cylinder? What is in my future if no repair is done? The motor runs fine at speed but has started to idle roughly and stalls.

 

[JB]

Re: compression 1998 johnson 115

Ahoy, AWOL.<br /><br />Looks bad, but there are a couple of things you can try.<br /><br />Compression can go away from carbon fouled rings or from a blown head gasket, as well as more catastrophic failures.<br /><br />What does the spark plug from the bad cylinder look like?<br /><br />Try squirting about a tsp of oil into the cylinder and try the compression again. Big improvement? Piston/ring sealing problem. Could be carbon. Decarb the engine.<br /><br />No improvement? Pull the head and look for a headgasket failure or major scoring of cylinder walls.<br /><br />Let us know what you find.

 

[awol1]

Re: compression 1998 johnson 115

the cylinder is the upper right when looking at the back of the engine. The plugs all look the same. no visible head gasket problems.

 

[thosch]

Re: compression 1998 johnson 115

I believe that the upper right (starboard) cylinder that tends to carbon up first on the v-4s. I remember dhadley's comments about moving the pee line connection to the top of the block on that side, and greatly reduced the carbon problem for that cylinder. Might be a long shot, but a decarbon job is worth a try before tearing into the engine.