Zero Compression in one cylinder ?

I have a 1996 johnson 112 special, 90deg cross flow 4cyl.engine. <br /><br />I have no power under load and its spits and farts but seems to start and idle.<br /><br /> Looking at the back of the engine, the top left cylinders plug is black with alot of cheese on it. I thought I fouled a plug, so I put new plugs and wires on. Come to find out I have zero compression in that cyl. (0 lbs) <br /><br />I have 90lbs, 105lbs, and 85lbs in the other cylinders. the engine starts and idles but skips and farts under load. I checked the comp. with all the plugs out and the engine was warm.<br /><br />Does this mean a top end rebuild ?? This is my first boat and Ive only been out six times, this sucks!!

Re: Zero Compression in one cylinder ?

yes it does. sorry for your luck

Re: Zero Compression in one cylinder ?

With zero compression on one cylinder, and a difference of 20 psi between the next lowest and highest, the engine needs a major overhaul.<br /><br />However, first remove the cylinder heads to inspect the pistons and cylinder walls. Perhaps (although unlikely) you've only blown a head gasket.<br /><br />Keep in mind that powerheads do not fail by themselves, something caused it. The usually cause is fouled carburetors which results in the engine running lean.