Rings worn or are they stuck?

[sledmonster]

Hi guys sorry im in this forum but I cant start a new thread in the rude/john forum?
1983 Johnson 150 V6, I have been having problems with the engine from fuel to low compression. Im wondering if my compression numbers are correct. I have 75psi on all cyls, I am new to the motor so It does not have alot of time on it.
My question is, can this motor be worn out so much that its reading that low? Or is it more likely stuck/choked rings contributing to the low numbers? I live in the snowmobile 2 stroke world and have never seen an engine get that low with free moving rings. They usually, with alot of hours loose 10-15 psi and keep producing alot of power untill they (squeak).

1977 16ft Sidewinder

 

[JB]

Re: Rings worn or are they stuck?

Well, if we can't start it in the JohnnyRude forum maybe we can move it there.

 

[sledmonster]

Re: Rings worn or are they stuck?

thanks for moving this. who ever you are do you know why i cant start a new thread in this forum?

this thread was start in the merc forum.

 

[sledmonster]

Re: Rings worn or are they stuck?

bump

 

[iwombat]

Re: Rings worn or are they stuck?

It can get that low with wear, but your hunch about stuck rings is more likely. Do a decarb and see if your numbers get better.

 

[jtexas]

Re: Rings worn or are they stuck?

possible measurement error? I'd have thought 100 was low, or 110. sure are wearing evenly, though, gotta admire that.

 

[Kevin W]

Re: Rings worn or are they stuck?

FAQ has a good proceedue to decarb it with seafoam.
Thats a good place to start.
Also when your checking compression all the plugs are out and your cranking it many revolutions to achive the highest reading.

 

[Windykid]

Re: Rings worn or are they stuck?

Also pinning the butterfly's open will eliminate a choke issue.

 

[perkdp]

Re: Rings worn or are they stuck?

Blown head gasket maybe ?

 

[Walker]

Re: Rings worn or are they stuck?

Blown head gasket maybe ?

Unlikely with the same reading on all 6 cylinders

 

[sledmonster]

Re: Rings worn or are they stuck?

Thanks guys,

I took a look in the exaust cover, rings arent stuck there but the ends could still be? I'm going to re-assemble and use another gauge. Any ideas on sealant for exaust cover gaskets?

 

[sledmonster]

Re: Rings worn or are they stuck?

could it be crank case seals? breathing between banks?

 

[sledmonster]

Re: Rings worn or are they stuck?

Pulled a head off on sunday. Bores are stock 3.500" maybe 0.002" out of round but pistons have at least .020" -.030" in the wrist pin direction and .040" - .050" in the other. !!!!!!!! Holy crap I couldn't believe how worn they were.

So I have a 6 new standard kits coming, gonna do a crosshatch on them and call her good and in the mean time rebuild carbs.

Can't wait to try her out with a fresh motor.