Well it appears my shitty luck with the GTO continues. I recently found that all the exhaust valve seals had pulled up off the guides. Called my head guy and was informed to pull the springs, inspect the seals for interference, and if all checked out throw a new set of seals on it. No biggie, $30 is way better than the $2000 last year due to a broken spring. So i order the seals and today I decided to put them on. First 2 cylinders went fine, when i got to cylinder 8 it won't hold any air at all..WTF.. With 120# in the tank it bleeds down as soon as I hook the line up. The previous cylinders all had an audible leak but they held air to the point the compressor would kick on/off. Cylinder 8 will not and with the compressor running it doesn't get above 20PSI. It sounds like it's going into the crank case but it's hard to tell due to the amount of air leaking. I can't hear anything in the exhaust and it's not coming through the intake. At this point i'm guessing it's a ring land or a hole in the piston itself. What's weird is the car sounded and drove perfect when i parked it. Is it possible for a motor with a hurt cylinder to act fine? I've been logging the car with EFI Live and never saw anything out of the ordinary a side from a few degrees of kr that we have been having a hard time getting rid of. The car has been sitting for over a week but i have a hard time believing that heat would make that much of a difference. Anybody with any ideas please let me know. I'm thinking the motor is coming out yet again.Thanks for any help

 

If you can, pour a small amount of oil in through the spark plug hole then hook the air back up.

If that slows the air down, than most likely its the rings/cylinder wall that are the problem.

Sounds shitty, prepare to yank the motor out...

Also need to figure out your guide seal problem. Sounds like there isnt enough clearance between the guide and seals..

Good luck

 

Well for the guides it seems like a loose fit may have been the issue. All the seals I did pull were intact and had no evidence of contact at all. I thought about the oil thing after I left the shop but the fact that it doesn't hold any pressure at all leads me to believe I have a much bigger issue. If it does have a busted ring land or a hole in a piston wouldn't it smoke? The fact that it ran fine with no issues other than an occasional puff of smoke at idle ( reason I looked at the seals) has me confused. Thanks for the help, I think the motor is coming out as well

 

I would think it would smoke as well, but sometimes engines do funny **** and dont do what we normally think they would do.

Stupid question, but the rockers were all the way backed off correct? lol

Also, look at the plug that came out of that cylinder. If it was burning oil it should be visable on the plug.

 

Plugs looked fine and all rockers were off. I'm really lost why it ran fine but won't hold any air