I have low compression on the farthest back drivers cylinder. When i did the test the other 7 cylinders were all in the 130 range except for the one it was 50 psi. I've pulled the heads because my cat was clogged really bad wouldn't go over 50 mph and I really rodded on it to get it going that fast. I drove it around with a clogged cat for 200 miles I know stupid idea. I was thinking I burned the exhaust valve but when I pulled the ehaust valve it looked good. The intake valve is a whole nother story it is caked with carbon and the bottom of the valve there is a big divot but nothing broken off from the valve. I'll get pics of the valves and seat on the dead cylinder later today. I need help guys the motor is all torn down for the plenum and the tranny is out also but I've got a rebuilt one going in. Please help me figure out this compression issue

 

OMG! Call me a "giant dick" I don't care! I'd love to try and help, but that is one of the longest most confusing run on sentences I've seen in a while. Sorry, but come on dude.

 

Haha sorry. I was in a hurry and on my phone posting that I'll edit it with the periods and try to elaborate.

 

That would be much appreciated. By all of us. Anyway, as far as I can tell(after my headache is gone) LOL your problem most likely is the result of excessive heat, due to a blown plenum gasket,clogged cat and bad pre cat o2 sensor. Do a search here on DF for plenum.

 

haha is that better zman?

 

Yeah I'm definitely thinking the excessive heat and back pressure is what caused it. I think my real question is wheter it is rings or the valves? When i did the wet test my friend put in WAYYYY to much oil and in turn wrecked the compression tester so I can't redo that test. I'll also get pics of the piston and cylinder wall on the dead cylinder

 

Lets see a pic of the valve.

 

The head is the main issue, it is most likely cracked from the excess heat.

 

hey you - i'll get you a pic later today when i go over to the barn to continue working on the truck

zman - if the crack cant be seen visually the only to tell would be to get the head hot bathed and magnafluxed correct? Unless there is some other way that I dont know about?

 

If the valves are that bad, you need a machine shop to check the head.