Need this running asap take 2

[blindmist]

Are you sure you don't have a vacuum leak? With good compression and no leak, you should get somewhere around 17hg/in constant, regardless of cold or hot, at least thats how it is on my car. I am actually thinking my gauge shows closer to 20hg/in at idle. This just really might be me though. I haven't really paid very close attention lately.

[Mean Green]

that shit that was round the valves may have got into the turbo impellar. just a thought?

That was on the front head, that bank is fine now...its just the rear with the problem now like before.

[Mean Green]

Are you sure you don't have a vacuum leak? With good compression and no leak, you should get somewhere around 17hg/in constant, regardless of cold or hot, at least thats how it is on my car. I am actually thinking my gauge shows closer to 20hg/in at idle. This just really might be me though. I haven't really paid very close attention lately.

The intercooler piping was pressure tested up to 30psi and had no leaks. I've plugs the brake booster and removed all lines except for the boost gauge and it does not change.


I just don't know what else to do. I checked the rear turbo also and it spins freely. There is literally nothing else I can replace on the car to eliminate something except the rear head. After I put a brand new FPR on the car, that was the last thing I could buy and replace. I even put a different plenum on the car and throttle body.

I just don't know what else to do at this point except replace the rear head.

[Mean Green]

YAY! confirmed the problem this morning.

I kinda sorta fixed the low vacuum problem. The idle screw had worked it's way out. I screwed it all the way back in and out 1 turn until I got proper idle and it was reading 16/17hg at idle but I have yet to test it against a cold idle. I also bought a nice big vacuum gauge and cofirmed the sticking valve guide theory. The vacuum suddenly pops from 18hg vac to 10 hg and suddenly back up every once in a while. I also was able to put a 1$ bill against the exhaust and it sucked it in on 1 compression stroke, of course it does not determine which cylinder it is but considering I just replaced the front head and the rear bank is having the issue, that pretty much narrow's it down.

I'm going to go pick up a replacement head this morning and hopefully have it swapped out by tonight or tomorrow. I drove the car with the vacuum a little better and it will boost and run decent but still not alot of power and it still hits something along the lines of a fuel cut at 4300rpm.

[Mean Green]

I got the rear head off and I am dead tired. I sat the head down on the ground sideways and poured gas into the runners. Cylinder 2 and 4 could not hold the gas just in the runner on the intake valves. I could not see any visible damage so I am very unsure as to what has caused them to what would seem to be sticking. I am just glad that I took the head off and found a problem...hopefully I can put some closer on this mystery that has plagued my car for well over a year in a half. The exhaust valves did the same thing as well...

[SpdDmnVR4]

I hope you figure out what caused that.. That's a strange thing to happen with little to no other damage to the head, block, or pistons

[Mean Green]

The cam timing was never off to begin with. The guides where not installed right at the machine shop so the valves are kinda overlapping the seal by just a hair. I just don't understand how I did not notice it to begin with.

[CoreyB]

The cam timing was never off to begin with. The guides where not installed right at the machine shop so the valves are kinda overlapping the seal by just a hair. I just don't understand how I did not notice it to begin with.

This doesnt make any sense to me. Can you clarify?

[Mean Green]

This doesnt make any sense to me. Can you clarify?

When they drilled out the old guides, they installed the new ones crooked. The valve will snap back into place at lower RPM but would slam against the valve seal at higher RPM. They are only off just a hair but its just enough to cause it to not seat properly. It is really hard to explain without you being able to physically see it, I tried to get pictures but I cannot get enough light in to show it.

Once I removed a valve spring, I was able to move the valve side to side by hand with barely any effort...so over the time of it being installed wrong, it has worn the new valve guides out due to them being installed incorrectly.

[CoreyB]

I think I follow you. This would mean the head is junk wouldn't it. I thought that old valve guides were pressed out not drilled. Drilling seems to leave the opportunity to not drill straight, which is what sounds like happened if I follow you.