apitts73

so......i have this new motor(3.0) turbo, has been running really well(no dyno tune yet though) and now has 2100 miles on it.
it has a vitesse maf/v-flex, and the afr is fine(11.6-11.9 full boost), but @ only 15psi boost and only around 5800rpm....she blew the head gasket!!
anyone know why this could have happened at this fairly low boost level?
what should i look for when i take the head off that might point to the problem?
thanks for any help guys,
adam

minho78

Adam sorry for all your troubles. How did you find out about the blown HG? A simple misfire can cause it.GL

apitts73

i pulled the spark plugs and 3 or 4 of the cylinders had coolant in them.
now i need to find out WHY?

Bri Bro

Didn't you run lean, cutting out and backfire because of a loose DME chipboard a couple of weeks ago?
https://rennlist.com/forums/8378351-post1.html

lart951

do you have a wideband, or a datalogger. warped head or block would do it but must likely it was detonation. Who build the engine and who tuned.

Best Regards

Lart
self certified 951 forensics tech.

Tom M'Guinn

Well, that'd do it.. What pistons and compresion ratio are you running in that motor?

apitts73

Brian Broderick,
yes...actually it ended up both chips were loose....but since then(about 1500 miles), it has almost been great. i say almost because it ran really well until i raised the boost to 15psi. when i boosted hard in 4th it cut out for a second or something.....im ultra sensitive to every sound/knock/creek/etc. since installing this new motor, so when it cut out i would take my foot off the gas within a split second probably of feeling it cut out. but slower accelerating in 4th up to 15psi boost was fine.
i was hoping to get to the dyno this week finally, to check that out and fine tune it...but i guess not now!!

Lart,
do you have a wideband, or a datalogger. warped head or block would do it but must likely it was detonation. Who build the engine and who tuned.

Best Regards

Lart
self certified 951 forensics tech.

yes, i have a wideband
it was built by LR
not tuned yet...just the tune that john @ vitesse did on the chip(maf/v-flex)
afr was fine the whole time
and i would hope the block or head isnt warped w/ just 2100 miles on them!

thanks for any help/suggestions

Tom M'Guinn

So what pistons/compression ratio do you have?

lart951

Honestly like Brian said if the chips were loose and created a lean mixture it only takes a second to blow a hg. In my experience blowing hg's sometimes it happen with a big cloud of white vapor, other times the coolant would be sprayed by the exhaust, and sometimes the car didn't start because the cylinder chambers were filled with water and at last none of the above but the coolant level would drop in the reservoir after every drive. The initial damaged could have occurred a few weeks back and the HG has been deteriorating to the point that passes a lot of coolant. Fixing it is obviously important how it happen and why it happen is even more. If it was the loose chip well it was a freak incident, but if it wasn't the loose chip......................

schip43

Sorry guy, but with a lose chip all bets are off. Just take a deep breath buy a six pack and dig in! I think blown HG's are a part of 951 ownership.

apitts73

not sure about pistons and compression ratios.. but it was built as a turbo so im sure they are good.

when it ran lean a couple weeks ago...it wasnt too lean...i think 12.2afr full boost.
i agree it could have happened then....but i really doubt it.

for sure if its only a head gasket...no problem...done about 7 of them in the last 4 yrs on the last 2 motors.....but this is brand new...it shouldnt have blown!!

why else would it blow w/ only 2000miles on it......
when it happened, i was in 4th gear around 3000rpm and i down shifted into 3rd about 4000rpm and hit the gas, full boost until around 5800rpm and then shifted into 4th....looked back and noticed smoke out the back end. i shut it down right away and coasted to road side.

like schip43 said HG failure is fact of life and its not a huge deal to do....just if it keeps happening again...like when i first got the car 4 yrs ago and 7-8 HG failures and 2 motors later i found out the WG was on backwards from the last owner...thats why he sold it!! but anyway i didnt know about turbo cars or the 951(just loved it since a little kid)....
now i know alot more, and i really dont want to blow this motor, so i should really find out the cause...if i can
thanks so much for the help and suggestions guys,
adam

Black51

Not sure about the compression ratio and pistons?? Didn't you have it built? That's kind of important to know about in any, but especially in a turbo application. It's unlikely that it was, but what if it was say a 10:1 or higher compression ratio? If you aren't sure about that, why would you run it at 15psi?

Based on the evidence shown, I would bet you're getting detonation running at 15psi boost.

Willard Bridgham 3

What is the compression ratio?

apitts73

seriously guys....it was built as a turbo, with the right pistons and comp ratio....by LR....

Tedro951

As to your question, you can get a lot of guesses on here, but looking at the gasket is the answer.