Engine Head gasket blown? Twin turbo Cobra

konfla · Feb 24, 2021

Went to PBIR track last night to try out my Cobra. Its a 5.0 91 block, alum heads, 303 cam, twin turbo with 6lb boost. After a few practice sessions I felt more confident and hit about 110 on the straight. Huge clouds of white smoke on drivers sidepipe, but oil pressure was still good. Limped into pit and found it was steam from coolant. Guess next step is compression check, but any tips/help will be appreciated.

konfla · Feb 24, 2021

Compression was ok, all around 150 +-. All plugs bleach white. Took the EFI upper intake manifold off and it had about a pint of coolant in it. Turbos were wet inside. Most all cylinders had coolant. Really at a loss as how the fluid could get in upper manifold. Anyone with turbos have some answers for me?

konfla · Feb 24, 2021

Have I posted in the wrong forum?

dgollem · Feb 25, 2021

I'm not much on turbos but I have never heard of coolant getting in them. The only thing I can think would cause this is a leaking water-cooled intercooler. Do you have a one on your set up? If you do maybe there is an internal leak pulling coolant into the air stream. I don’t even know how a blown head gasket would be able to back flow water into the turbos and intake. Hope you figure it out and hopefully someone with turbo experience will chime in, I usually see some good advice to post like yours on this site. good luck.

7991LXnSHO · Feb 25, 2021

Have some patience. 12 hours over night for an odd/unusual question to be answered is a short wait time.
Besides the intercooler, do you have the EGR plate hooked up to coolant? It’s sealed with paper gaskets, and is attached to the upper intake.
It’s time for a coolant system pressure leak down test. Pump it up to at least 12 PSI, leave it pressurized and see where the coolant comes out.
I have no idea about coolant in the turbos if these two ideas are not it.

konfla · Feb 25, 2021

Thank you both for your input, sorry for my lack of patience. Can't sleep trying to figure this out. No EGR plate or coolant there. Intercooler is air cooled only. Will do the coolant pressure test. What really puzzled me was all plugs white and water in upper manifold/turbos.

General karthief · Feb 25, 2021

Intake gasket? Coolent enters the cylinder, out the header, into the turbo, into the upper intake?
Just thinking.
Probably shouldn't do that

a91what · Feb 25, 2021

Are the turbos oil only or are they fed coolant? Do you have milkshake oil? how does the oil look and smell?

Proper feedback will require you to give us as many details as possible to help in the troubleshooting process

7991LXnSHO · Feb 25, 2021

General karthief said:
Intake gasket? Coolent enters the cylinder, out the header, into the turbo, into the upper intake?
Just thinking.
Probably shouldn't do that

That or a head gasket are next on my list. The pressurized coolant system check while not running should help. I just hate to tell him to tear it apart without a probable diagnosis.
@a91what, good question about the oil. Want to wager on the answer?

konfla · Feb 25, 2021

Just blew some air in radiator cap and water came out cyl 6. Next I plan to remove rocker arms to close valves and try it again to see if its intake. I didn't want to tear it apart without diagnosing first. Will keep you informed. Thanks so much for the help!

a91what · Feb 25, 2021

7991LXnSHO said:
That or a head gasket are next on my list. The pressurized coolant system check while not running should help. I just hate to tell him to tear it apart without a probable diagnosis.
@a91what, good question about the oil. Want to wager on the answer?

I am gonna say it does have water in the oil, and likely it will be head gaskets. The next question will be why at 6psi did he drop the gaskets.... sounds like the tune may be very aggressive

konfla · Feb 25, 2021

Surprisingly no water in oil. Oil looks new still. Maximum advance i think is 30* with less under boost. Turbos oil cooled only. PO told me it was set for 6 lbs but I don't know for sure. I bought a WB fuel air meter to make sure the tune wasnt too lean and it seems to be on the rich side.

ECU is Microtech from Australia and a whole other story.

7991LXnSHO · Feb 25, 2021

Is the Microtech ECU a good thing or a worse story?

konfla · Feb 26, 2021

Microtech has no customer service. Antiquated software. Doesnt use MAF sensor or A/F ratios. so its limited. It works but get alot of haters in the tuning world and no one is familiar with the software too much.

konfla · Mar 10, 2021

So it looks like it was blown head gaskets. Both sides in three places. Everything's back to normal now. Can someone tell me if I have to re-torque heads after a while or am I good? Can't thank everyone here enough for their help.

Monkeybutt2000 · Mar 10, 2021

What head gaskets did you go with? Stock head bolts or ARP? You may want to look into a different ecu,Microquirt is very reasonably priced.

konfla · Mar 10, 2021

Stock headbolts, can't remember header gasket name but looked like layered tinfoil. Would love to go to microsquirt but its a lot of work to change over. Current setup doesnt have an MAF sensor.

a91what · Mar 10, 2021

The vast majority of the aftermarket ecu will not use a MAF sensor. they are all tuned speed density, nothing wrong with speed density and most of the OEM are using speed density today on the turbocharged engines. the issue is that on a boosted engine the maf sensor can read the mass flow but not the air density under boost. This is easily tuned around using multiple tuning strategies. I use MAF and SD on some tunes and SD and Alpha-N on others it really depends on the setup.

a build like yours at low boost should not be having head gasket issues at 6psi. I would have to get into the ecu and look at the ign tables and a datalog of the run under WOT to see the AFR.

usually a lost head gasket is a timing issue... cars tuned on the dyno are not really tuned for real world use... just my experience

Steel1 · Mar 10, 2021

You don't need to re-torque head bolts after final torque down.
Honestly with a boosted engine I would have gone with ARP studs, but that's me.

7991LXnSHO · Mar 10, 2021

It has been a while since I have read instructions to retorque head gaskets.

Engine Head gasket blown? Twin turbo Cobra

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