Low compression

karkrazy1971 · Jun 8, 2024

1994 Silverado 5.7. I have low compression on one cylinder and the leak down test indicates an issue with the rings. I’ve read a stuck piston ring can cause this? Anyone else experience this?

If I do need to get into the engine, is it better to rebuild or go with a long block? Right now I’m just focused on reliability and will modify later?

95burban · Jun 8, 2024

If the truck was sitting along time and you brought it back from the dead sometimes if it has a stuck ring it will fix itself, if not she probably just worn out.

Personally if the truck is in great shape I would get a replacement engine from GM or Jasper. Another good option is a long block, that way it’s on the builder if something isn’t right.

WICruiser-97 · Jun 8, 2024

You didn't say how many miles on the engine but one piston having stuck rings is uncommon but not out of the question. You may want to inspect the cylinder condition with a camera though the spark plug hole. If the bore is gouged rebuild is probably not an option.

I tend to prefer rebuilding to a long block just because then I know/am resonsible for the results.

pressureangle · Jun 8, 2024

Cheap bet; put a pint of Marvel Mystery oil in the crankcase for a few hundred miles. If it's a stuck ring, that will get it loose. If it isn't, you're out $8.00.

karkrazy1971 · Jun 8, 2024

Thanks all. It has 161k and all the other cylinders have good compression. I read you can use Seafoam, but there is a chance you can hydro lock. I’ll see if I can borrow a camera and inspect it

95burban · Jun 8, 2024

Ice cold water works miracles, good steady high rpm and slowly pour the water down into the engine. The steam cleans the carbon away.

karkrazy1971 · Jun 8, 2024

95burban said:
Ice cold water works miracles, good steady high rpm and slowly pour the water down into the engine. The steam cleans the carbon away.

I’m going to rent a scope and try that if it’s just carbon

Erik the Awful · Jun 9, 2024

95burban said:
Ice cold water works miracles, good steady high rpm and slowly pour the water down into the engine. The steam cleans the carbon away.

I prefer to use the term trickle instead of pour.

95burban · Jun 9, 2024

Erik the Awful said:
I prefer to use the term trickle instead of pour.

Agree, trickle is the better word for this situation.

karkrazy1971 · Jun 9, 2024

I used a scope and there is a lot of carbon on the pistons. Unfortunately, the valve covers are really on there to where I will likely destroy them to get them off. I want to see the condition of the cylinder walls before I make my next step

Low compression

karkrazy1971

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95burban

Friends don’t let friends use spindles.

WICruiser-97

I'm Awesome

pressureangle

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karkrazy1971

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95burban

Friends don’t let friends use spindles.

karkrazy1971

Newbie

Erik the Awful

Supporting Member

95burban

Friends don’t let friends use spindles.

karkrazy1971

Newbie

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