Could mean a few things, could be a blown head gasket (not likely as you should see other symptoms), could be a cracked head, Could be a burnt valve, could be bad rings.

You saying that you don't see blue smoke on start or while driving mostly rules out bad rings. I'd lean towards cracked head or burnt valve.

Time for a leakdown test.

Travis

 

I always thought with a cracked head youd be able to see the crack pretty easily. and i also thought that even a cracked head still had some pressure in the cylinder.

so does that mean it leans more toward a valve that is open or something?

 

May be as simple as excessive carbon build up. You could try doing the seafoam thing to your engine. See if that helps. Compression test would give a clue, leak down test would tell the tale.

 

Not sure if you saw on the previous page, he did a compression test:

"Alright so i did a pressure test on the passenger side so far. these are the numbers i get.

Cylinder 2 was 110 psi
cylinder 4 was 100-105 psi
cylinder 6 was 120 psi
cylinder 8 was like 0 psi.


cylinder 1 was 100 psi
cylinder 3 was 95 psi
cylinder 5 was 110 psi
cylinder 7 was 117 psi

these were all dry test. now i know 0 psi in 8 is my problem with the misfire, but what does it mean?"

 

Yep. Missed that. (Its gdstocks' fault..... )

Zero compression is indeed a problem. Leak down will tell you if it is a valve, or, a hole in the piston......

 

HA! Sitting here minding my own bidness....

Carbon could still be an issue (although not the most likey) if it keeps valve from closing. May also pop the valve cover orr, remove coil wire, and have someone crank engine. make sure the valvetrain is all moving properly. I had an old chevy about 30 years ago that had 0 compression. One of the valves bent and would not move, leaving chamber open. Checking this is pretty simple. Still have t remove head if this is the problem....

And a cracked head - No. most cracked heads I have had/seen were not readily visible. Some crack between valves. Some are so minute that they cannot easily be seen without magnflux or something similar. They do not normally crack to the outside where the crack is highly visible.

 

Removing the o2 sensor with it still fairly hot is easiest. Just be sure to not burn yourself. Also you vould have a broken valve spring causing that 0 on cyl 8.

 

you said you just repaired a blown plenum gasket, no?

that cylinder sits on the back passenger side of the block.. is there any chance you didn't seat the gasket good? If'n I were you, I'd cross my fingers and pray that you gotta gap and are losing compression there.. otherwise- you gonna spend some bling getting that rascal rolling again..

 

Intake manifold will have zero affect on compression....... He has an internal problem somewhere. (valve, rings, piston.....)

 

i need coffee..

you is right.. valves close ya big dummy (that would be me)..

having zero is badbadbad.. if'n it were just a seat cracked, he'd still have some, however momentary..