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For those of you who have damaged your head gaskets with too much boost, when you removed the head to replace the gasket, was the blown gasket visibly damaged/cracked?

I blew my HG about 3 months ago while tuning the car with a faulty wastegate actuator (which caused all sorts of boost spikes 11+ psi). I got the common symptom of a pressurized coolant system with all of the coolant pushed out through the overflow bottle (and then an overheated motor). Later on, I had the coolant system tested chemically which proved that combustion by-products were definitely leaking into the coolant system. Anyways, the headgasket is being replaced now. Everything looks good with the head off: pistons are fine, block is fine, head is not warped or cracked (passed all pressure tests).

What I find odd though is that the old head gasket doesn't appear to have any major damage. Some of the rubber seems to be damaged, but the metal part is still intact and not at all cracked.

What did your head gasket damage look like? I'm just worried that there's something else wrong -- not the head gasket. Not sure what it might be though, given the described symptoms.

On a related note, what's the latest general consensus on what the max pressure our stock head gaskets (with stock head bolts) can withstand before cracking? 8 psi daily seems to be safe for most people -- properly tuned of course. What if you see random boost spikes around 10 psi here and there? Is that okay?

Any thoughts?

Thanks,
-jB

 
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11psi daily is what some of us are running its all about the alcohol injection
that is why SF rules...

and from what little i know.. sometimes the headgasket gets flattened or pressured which causes it to leak but not break. i duno thats just my 2 cents..

 
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WRONG

 
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does ARP make head bolts for our application? maybe they would hold better under the stresses of boost.

 
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dont hate .

alcohole injection is the way to go if u dont have the $$ on hand to do internals...

so take ur PHD degree somewhere else

(Playa Hatin D1ckhead)

 
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I went through 4 head gaskets. None of the metal was cracked. That isn't what makes the seal. The rubber rings that go around the cylinder holes are what go and cause the coolant to get into the cylinders.

 
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You should also inspect the head for cracks in the combustion chamber and also make sure the head isn't warped. I'm not too sure if either is a common problem on the D17 or not. Im not familar at all if our block surfaces can have an effect on the sealing of the combustion chamber, but im sure you would want to make a inspection of it too.

 
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head gasket can leak where you cant see it... under pressure little cracks taht you cant see get big enough to cause trouble....

 
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How would alcohol injection make a diff? you still have the same amount of pressure pushing on the gasket, and the rest of the internals. Alcohol just helps w/ cooling and detonation.

 
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Well, detonation can cause pistons and rods to break, believe it can cause headgaskets to blow as well.

 
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im not hating just that some/if not most people on this site have ALCHY INJ so far stuck up their *** that not even an enema a day would dislodge it

 
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head gaskets mainly blow because of slight detonation. Dont go and say its from too much cylinder pressure and that it never detonated. Dave hickman ran 9's on the stock head gasket. If you prevent it from detonating, you wont blow a gasket easily. If his boost was spiking, then he was most likely running into light detonation. The alcohol does an extremely good job at preventing detonation.

 
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alot of drag cars use OEM head gaskets b/c u are better off having the gasket blow to alert u of damage b4 something serious get screwed up.

 
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This is very true as well. It's good to have a weak link instead of destroying a piston.

 
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settle down children...

 
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I don't have a turbo, but wouldn't you want to replace the HG just for good measure? Might as well, since you are there already.

 
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Why would you do that? Unless your gasket is already screwed. When installing a turbo, you don't pull the head. You just pull the header/exhaust manifold. A head gasket is what makes the seal between the cylinder head itself and the block/deck. The exhaust manifold bolts up to the exhaust side of the head.

 
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but isnt it a good idea to put a thicker head gasket on inorder to lower compression slightly?

 
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If you do a thicker gasket, you have to retard the cam timing. Or else the timing will be all screwed up. And advancing the timing on a turbo car is bad. When you put the thicker gasket on, it raises the head, which advances the timing because of changing the geometry of the timing belt.