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Do rings get stuck How to free up

fishinvol

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1990 200 hp looper- low compre

1990 200 hp looper- low compression on both bottom cylinders-55-60 psi. Pulled head and there is no cylinder wall damage?? Motor has beem built .30 over. Could the rings be stuck?
Pistons clean enough to read part numbers.
 
"rings can and do stick....use

"rings can and do stick....use a decarb solution,..lower cyl's can end up lower than the others..but u do have a prob.."
 
Thanks for responding- others

Thanks for responding- others are 87-90psi
Rebuild time frame unknown- it has a rebuild "serial number tag" from PMC. I have decided to go ahead and tear it down- I am about 2/3's way there-stopped for lunch and saw your post. I will post my findings and questions as to "WHAT Now" later.
 
be sure and get u a FACTORY se

be sure and get u a FACTORY servce manual...it has all the info u will need to rebuild it properly..
 
The rings on the lower cylinde

The rings on the lower cylinders are more suspect to sticking because they handle more backpressure than the cylinders higher up. Allowing carbon build up behind the rings. Proper engine height on transom will help prevent increased backpressure. If the exhaust ports on the leg are close to or under water it is mounted too low
 
Thanks-I do have a factory man

Thanks-I do have a factory manual- What size socket do I need for the rod bolts? 12 point something- manual says socket is 331638 - that helps alot. I am ready to pull pistons and do not have a matching socket.
 
"5/16" X 12- I found ever

"5/16" X 12- I found everything quite clean- however I did find the following:
Bottom 2 pistons with low compression had ring lip on cylinder wall more pronounced than top of same cylinder and other pistons did not have this.
The rings removed from same low compression cylinders were thinner (.020"/ 0116 vs .136)) measured ID to OD, opposite side from gap. I checked one of the higher compression pistons as a baseline and found .002-004 varition. Something is out of round-or wearing hard towards bottom of engine.
Pistons from both higher compression and low compression cylinders all have have lower skirt scuffing- no cylinder wall damage visable and no transfer of aluminum."
 
thinking u could have had a lo

thinking u could have had a low ratio failure..most vro failures are due to not keeping the system in good shape.
 
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