Is there a way to tell if my rings are bad or if I have mabe a valve issue.If its the head id hate to pull the whole motor out if i dont have to. I have a 96 disco that i just did head gaskets on. When i took the heads off the # 2 cylinder had a major gasket blow out so i assumed that was the problem. All the valves looked ok and they looked to be seating rite. When i got it all back together and started it, it started anit idled fine but would pop and misfire when i tryed to rev the motor(likethe timing isnt right). So i just did a compression test and the # 2 cylinder that had the blown gasket has only 90 psi when all the others have around 145. Would this cause the engine to run this way? It has 140k on it and im afraid im going to have to just put a new motor in it. I assume there is no easy fix if it has a bad cylinder?Thanks.

 

How many miles on the engine?
You should do a wet and dry compression test as well as a leak down test, that will give you all the info you'll need.
Mike

 

Redo the compression check.
Check it then squirt oil in the cylinder if the compression goes up bad rings,
stays the same bad valves.

 

thanks guys..the oil trick is smart i never thought of that...The truck has 145k miles on it. My next question would be, would the low comp cause it to run the way it is or do I have some electrical isuue as well?(it starts an idles perfect but when i try to rev the motor it pops and misfires real bad). Should'nt the motor still run ok even with lower comp in a cylinder or two just not have the best horsepower? thanks again for your advice.

 

I put some oil in the cylinder that had 90psi(#2) in it and did a comp test again and it bumped up to 120psi. I had another cylinder (#7) that was showing 110psi and with oil added it bumped to 120psi as well. Im getting the tools this afternoon to do the leak down test. If it is my rings is it a nessary fix? im starting to think its running like s### is due to another problem.