Cylinder Compression

[TTA984]

What is considered normal compression when doing a compression test? In other words what range is OK.

 

[72firebird]

The general rule is all of the cylinders should be within about 10% of each other. I believe most of mine were right around 130.

 

[TTA984]

The general rule is all of the cylinders should be within about 10% of each other. I believe most of mine were right around 130.

Got it at the shop and had it tested, all the cylinders were in the correct range except #4 it had only 8lbs of pressure.

 

[8289ta]

That sounds like you have a blown head gasket.

 

[TTA984]

That sounds like you have a blown head gasket.

I hope that is the case or if it need 1 piston it is better than having to rebuild the whole engine.

I am glad I got a 2nd opinion, the first guy I took it to said I had hardly any compression in any of my cylinders, seems to me he wanted the extra $ for having it rebuild. It only needs 1 cylinder fixed.:cool1:

 

[72firebird]

You sounds like it's probably a head gasket or broken valve spring. Shouldn't be too bad of a fix, but how long has it been like that?

 

[TTA984]

You sounds like it's probably a head gasket or broken valve spring. Shouldn't be too bad of a fix, but how long has it been like that?

It started smoking out exaust and smoking out vent pipe on pass side valve cover about 3 miles from home. I took it home and parked it. I have not been driving it because it is like driving a car with 5 cylinders, and besides some smoke would get inside the car from the vent pipe really bad. After this happened it would run but barely. All this happened at around 15lbs of boost on a back road.

 

[TTA976]

I am glad I got a 2nd opinion, the first guy I took it to said I had hardly any compression in any of my cylinders, seems to me he wanted the extra $ for having it rebuild. It only needs 1 cylinder fixed.:cool1:

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