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blackawdtsi
11-12-2007, 09:26 PM
I have arp headstuds and a Commetic metal head gasket all torqued down.

When was the last time you retorqued them?
Thor06
11-12-2007, 09:38 PM
Would that show up in a leakdown test?
I dont think so, I think thats mainly tests for bad rings or bad valve seats, someone correct me if I am wrong.

Definately sounds like a tweaked headgasket to me.
blageo23
11-12-2007, 09:46 PM
Pop off the RAD cap and if there is bubbles during a leakdown test its caused by a bad HG. I know that a blown one would but would a blown headgasket like they are saying show it?
JET
11-12-2007, 11:29 PM
A small leak, like this seems to be, does not always show up. Yank the head and check it out. Might as well replace the radiator cap first though, for the heck of it.
Pushit2.0
11-12-2007, 11:35 PM
If it only leaks under boost the ~100psi you put in there on a leakdown test will not show a blown head gasket.

~John
jhaan_dude
11-13-2007, 02:16 AM
johns right, considering the stock motor makes 135 psi in the cylinders, that wouldnt work, but back to the part about the studs, did you ever retorque them????? and have you tried putting a little oil in the cylinder and done a compression check to see if you even get 135 psi per cylinder?!?
blackawdtsi
11-13-2007, 02:29 AM
johns right, considering the stock motor makes 135 psi in the cylinders, that wouldnt work, but back to the part about the studs, did you ever retorque them????? and have you tried putting a little oil in the cylinder and done a compression check to see if you even get 135 psi per cylinder?!?

I thought stock was 160 and the service limit is 130??
blageo23
11-13-2007, 10:06 AM
johns right, considering the stock motor makes 135 psi in the cylinders, that wouldnt work, but back to the part about the studs, did you ever retorque them????? and have you tried putting a little oil in the cylinder and done a compression check to see if you even get 135 psi per cylinder?!?

That oil thing doesnt work. Because our pistons have a dish in them all you are doing is filling up the piston with oil giving you a little bit higher number.
Shane@DBPerformance
11-13-2007, 10:28 AM
Under boosted combustion you might have 1000-2000psi of pressure in the cylinder, so often a simple compression test or leakdown test doesn't show anything for a headgasket that only leaks under boost.