Is it possible... good leakdown/good compression but leaks
 

A while back I posted about a noise I get from like 2500 RPM up when dropping the hammer. I really thought it was the gaskets on that side. Well nothing there!

We got rougly 210/220 PSI all cylinders.

Pumped up the cylinders and didn't get any notable leakdown.

I'm wondering if it could be poofing through the layers of the Cometic on the left side in the R's. I'm taking it to Fran's shortly to see if maybe an injector or something is causing knock.

Given good numbers could it still be a head gasket? Runs good other than in the R's on the throttle.

Damn this must be a stumper!

We scanned it and no knock.

Where are all the shop gurus

maybe a head gasket leak between cylinders?

I hear this noise to the outside. Wouldn't a leakdown show leakage between cylinders?

Motor problems... lifters, Cometics and unknown

Just read this too, and I'm :confused:

One thing - I did read that there were no bubbles in the coolant when you pressure checked it, but have you checked the coolant for combustion gasses? As indicated elsewhere, cylinder pressure will be much higher than pressure in the cooling system.

If you can't isolate anthing else at this stage, it may be time to pull the heads and check the lifters, reseal it, etc.

Good luck!

you could have a header gasket leak also besides a head gasket leak.heads off.

I changed the header gasket on that side and also the collector gasket. Could be a warped flange or something. We are swapping the cam this weekend so going to pull that header again and put a straight edge to it. Inspect it real good visually while it is out.

Usually you get a spike in the water temp gauge if you have hot gas going into the water jacket. None here.

Well, at least when you get the cam out of there, you'll know if you have a lifter that is sliding on a lobe....

Once again, good luck!

I hope we find SOMETHING. What happens when they slide and what causes it?

It's the hardest problem ever to find since it doesn't do it at all times and the car runs like it should.

Both from your other thread. I also noticed this:
and your reply
If that really is the case, either something mechanically let go when it was tuned, or the new tune may be causing detonation, as had been pointed out in the other thread.

Since your gaskets are weeping, you may be best off pulling the heads and looking for signs of detonation. You're going to have to fix that sooner or later, and if you do have an issue with detonation, you need to have the tuner address it before damage is done. While you are there, you can inspect the lifters to see what kind of shape they are in. Whether you pull the cam or not is up to you, as the lifters will tell you what you need to know.

I know you were going to swap the cam, but that really doesn't tell you much unless you find damage to one of the lobes. If that happens, your heads need to come off anyway...

Guess you missed that part. We hooked it up and made WOT pulls on the road recording it and got no knock. That's real world.

Gaskets aren't weeping that can be seen.

I guess if you can't find it on a scan, and adding race gas made no change, then you can rule out detonation...

At what point did you fix this? I read the other post from back to front and didn't see that you retorqued the head bolts anywhere.
I'm beginning to think you may be right looking at the cam. If not there, then it must be some kind of exhaust noise.

Okay so it is acting like my Buick did long ago with a head gasket problem. Today the temp spiked and it pushed out coolant. It's getting combustion into the radiator at certain higher RPM/Loads. So going to strip the heads off, notch the pistons and try again. Hope the block or heads didn't get flame cut.