I was runnin' at about 4200 RPM and all of a sudden the RPMs dropped to 3800 (and stayed there for awhile) and engine sounded like there was somethin' knockin' like when valves need to be adjusted [type of sound]. I shut the motor off immediately and drifted back the 4 miles to the ramp and only started it a couple of times trying to get away from the rocks and to the middle of the River and to finally get back to the ramp. But never rev'ed it above 2000 RPM. I should say though that I could barely get it to idle when attempting to restart as it kept stalling...
I also noticed that there was a lot of smoke coming out of the exhaust on the port side of the boat so figured that somethin' gave out on one of the cylinders on that side of the engine. Did a compression check and what do you know... all cylinders checked except one on the starboard side! which reads 0... nada... I mean no compression at all. To give you guys more clue, the spark plug on that cylinder is missing half of the tip on the center electrode.
So, here are the questions that I'd appreciate you guys' thoughts on:
- If the "no compression" cylinder is on the starboard-side, why is the smoke only coming out of the port-side exhaust manifold?
- I took the valve cover off and everything looked good as far as springs, push rods, rocker arm, etc. What do you suppose gave out inside that cylinder?
- Do you think that the fact that the spark plug is missin' half the tip of the center electrode, means that I'm dealin' with a nasty case of detonation, which could have caused a big hole in the center of the piston (and thus the reason for not having any compression)?
- Or could it just be the compression ring that somehow blew?
- One last question... I'm hoping that it is just a head gasket... But, shouldn't I be getting at least some compression if it was the head gasket or is it possible that blown head gasket could cause zero compression?
Thanx all in advance for your thoughts... I just don't want to start tearin' into it blindly and end up doin' bunch of unnecessary work.