Britdog15

Okay guys cut the cats off because i thought i had a clogged cat which i did and i ran it back to new mufflers. well it got rid of the cat code but not the misfire so i checked the compression on cylinder 8 and it was 30 psi. what should i do now?

Britdog15

theres a slight tick in the exhaust my grandpa said that could be an exhaust valve. and when i was getting the new mufflers on and the cats off the guy said he heard ticking on the driver side exhaust and said the same thing. i just am hopping its not rings.

cliffyk

Do a wet test to see if it's rings or a leaky valve...

Britdog15

just a little plain old motor oil? like a teaspoon?

cliffyk

Tablespoon (0.5 oz) or even a bit more--3/4 oz (half-a-shot glass)...

Britdog15

Okay i did that and it went up like 2 psi from the last time

BLKSTANGER

Pull the heads.

MyGt03

The best test I would think to perform would be a cylinder leakage test. If unfamiliar, its a tester that has two air pressure gauges on a metal block with a regulator. You hook it up to shop air. One gauge will tell you how much air is being pumped into the cylinder, the other gauge tells how much is leaking out and how fast. Usually give that number in a percentage.

You would bring #8 cylinder to TDC on compression stroke, thread leakage tester into the spark plug hole, connect tester to shop air, regulate to 50-60psi, and see how fast it is leaking out. Since you know air is leaking somewhere, you should be able to pinpoint where. If you hear a hissing coming from exhaust, it be the valve. If coming out your throttle body, intake valve. If pressurizing the crankcase, it's the compression rings, if coming out of the spark plug hole in adjacent cylinder, head gasket.

Now, I'm in no way a professional mechanic, but this is the test I would perform. Anyone else familiar with a leakage tester? I picked mine up at JCWhitney for about 80 bucks, if I remember correctly. If I am leaving something out, someone please correct me.

Its a good test that will help pinpoint exactly whats up and where your problem is. Every good diagnostic toolbox should have one in there.

Hope this helps. I could upload a picture if you would like to see one.

stevednmc

^^^^This! I havent used one in a while, but it helps pin point the issue. Only problem with this test is you have to have an air compressor, which not everyone does.

MyGt03

True, I should of pointed that out. Thanks. However, even one of them little pancake compressors for like a brad nailer would work. Just don't have it running while doing the test. As quiet as possible. You want to be able to hear the faint sounds of air leaking. It your best bet besides pulling the head an doing a visual inspection. And even then you might be stumped. Diagnose before tearing apart...