Head Gasket diagnosis?

[giulianot]

 here are some pics of the head gasket failure












i sent the head out for pressure test and check for warpage  i hope the head isn't cracked :mad:
 Is is possible that the head gasket failed from excess fueling or high egt's?
Are there any better after market options for a 1.9 aaz head gasket ?

[andy2]

I wish I had some good news but unfortunately It looks like you may have found the limit of the heatgasket and or head bolts.Do you have an EGT gage,How much boost,How much CC's fueling did Giles crank up the pump to? In my opinion these engines are good for eaxctly double the factory Hp.Beyond 140 hp on 24 psi with the t3 intercooled and not too much fueling (85cc's) almost everything has to be modified.

[giulianot]

i have an etg gage and i havent run the etg's past 1600-1800 degrees f and  normally in 5th gear holding at 100kph i see egt's of 600-800.
if i run the engine off the boost i dont get compression leakage into the coolant, as soon as i boost past 12psi compression leaks into the coolant and blows all the coolant out of the water bottle.
im not running more than 15psi boost, since my engine is still in its break in period well 300 km into my brand new motor I am getting compression leaking into the coolant under boost above 12 psi . If i drive it around and stay off the boost its fine but as soon ass i boost above ~12 psi my gauge over heats and it blows all the coolant out of the water bottle. any ideas what would cause this? I had arp ford cosworth head studs in torqued to 75flbs torque.  and that was a one hole gasket.

[andy2]

Is the pyro reading from before or after the turbo?I would probably try another gasket and torque the studs to 110 ft/lbs.It you've had the pyro up that high then I would'nt worry about turning up the boost asap.The lower boost (15psi) with higher Egt's will be more harmful to your engine than 22-24 psi with lower EGT's!I ran my new engine with 300kms on the dyno at 30 psi and 160 whp.I enlarged my cylinder wall to piston clearance to double factory to let the piston expand with the higher temps.Are you using total seal rings?

[giulianot]

my egt probe is reading before the turbo in the exhaust manifold. I think i might put in a two hole head gasket back in instead of one hole to compensate for the additional boost

[smutts]

Slightly off topic I know, but don't you guys get problems with distorting the block and bores with high head torques? Perhaps blowby and oil consumption and glazing etc?  :?:

[jimfoo]

That torque isn't high, it's normal for a stud depending on the lube used.

[jtanguay]

Slightly off topic I know, but don't you guys get problems with distorting the block and bores with high head torques? Perhaps blowby and oil consumption and glazing etc?  :?:

only until the rings seat to the shape of the distortion.

[subsonic]

Or you could bore and hone with a torque plate on top.

[andy2]

I torqued those studs to 115 ft/lbs.These blocks will not distort from higher headbolt/stud torque,The head might want to distort though.I Tightened a 12.9 grade capserew into my block until it streached the bolt :shock:.14mm threads are going into my block today.I'll post a pic of the comparison between the 12mm cosworth and the 14mm ones :lol:.

[giulianot]

SO i heard back from my engine rebuilder and he said that the head gasket failure happened because the steel pre cups were falling out of my aluminum head. This is not normal. The pre cup were nerled then pressed in then pinned. Anyways is under warranty, im getting a new head then i got to switch over my valves, springs, cam, injectors, glowplugs, over to the new head and have to match port and polished. It looks like i wont have my car back till after Christmas.

[mtnsammy]

I run 12 PSI all the time I climb hills and have yet to blow the head or gasket. I think you may have a small crack in your head that needs heat to show for the shop. If you are popping the gasket at stock torque then there must be warpage. Invest in a good straight edge and feeler gages. Check both head and block. The horrible shop I first used could not cut a head if their life depended on it. I found an old tractor custom head shop in Riverside and he did a top job for me. THe combo of steam blasting from a crack to blow the head gasket was common on old chevy small blocks in the 70's. Now the shops are better at chevy motors. The VW motor is becoming a lost art for machinists.

[giulianot]

The VW motor is becoming a lost art for machinists.

 I have heard this from many people many times  :roll: and it is very true!  When you send a head to get planed most shops use a blancher, and if they don't set the leading edge properly,  :roll: there can be up to .005 - .010" difference throughout the head! thats just unacceptable for me so i requested the head to be surface ground to within +/- .0005 " . A blancher will  leave your head concave/ convex where as surface grinding will insure flatness, If done by a competent machinist.

[subsonic]

SO i heard back from my engine rebuilder and he said that the head gasket failure happened because the steel pre cups were falling out of my aluminum head. .

The exact same thing happened to someone else on the forum.  What was the make of the head?