Reply To: ?????? Question Johnson QD-16

[tinkerman]

I have jumped around on this forum like a squirrel on crack but to clarify, I’ve kind of given up on the Johnson QD-16 at present as it DOES have noticeable scores in the cylinder walls that would seem to make it impossible to obtain good compression. I did manage to get the water pump working and it DID start but wouldn’t idle and smoked to high heaven (bun your eyes and throats smoke) after it ran a bit the compression went from 50 up to 60 but still really low from my understanding. So as I say I set this one to the side for now. The one I’m working on now is a 497 Scott Atwater . Compression felt really weak when I pull the pull rope. Checked compression and it was less than 40. Cylinder walls look great, no scratches. So I was looking for other suggestions for causes of low compression. I noticed the underneath of cowling was oily, sticky, greasy so I got to thinking maybe the crankshaft seal could be causing low compression. Even though underneath cowling is sticky oily, the engine is really clean. You wouldn’t look at it and say wow that’s a worn out piece of junk. As I’ve said I have 8 non running engines and EVERY ONE that I’ve check d compression on shows 50# or lower. (I have a 30 hp mariner on my boat that runs great and it shows 85 psi per cylinder so I’m thinking my gauge is ok. Are there any other “fixable” causes of low compression. I really do appreciate yalls patience and willingness to help

It's a jungle out there.