Author Topic: turbo V6, blew head gasket .. I think .  (Read 228 times)

28chevyguy

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turbo V6, blew head gasket .. I think .
« on: April 10, 2019, 01:55:29 PM »
So I got my turbo grand prix back together and blew it up already.   Top of 3rd gear max boost it started letting go , followed by a lot of burning coolant smoke and blew the overflow tank off the car.   Got the car home and started it up again ,  have a lot of compression entering the coolant system , a lot of bubbles - pressurized.  I figured no big deal just needs a head gasket.  Heres where it gets strange .  I did a compression test and got good compression on all the cylinders.   I don't understand how I could be pressurizing the coolant system that violently without showing a low compression reading on any of the cylinders.    With all the plugs out , cranking the motor over coolant  shoots out of cylinder #6  .  I just talked to my local machine shop guy  , asked if he's ever seen a blown head gasket symptom of pressurizing the coolant system yet none of the cylinders show compression loss.    He said " to be honest, no"

To all the smart car guys here.... where does this leave me ? cracked head maybe?? 

Rattiac

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Re: turbo V6, blew head gasket .. I think .
« Reply #1 on: April 10, 2019, 02:04:10 PM »
Is this the 3.8 V6 (231) ?

My first block had pinholes in the cylinder walls.
(Tiny air bubbles in the casting) wich didn't show up until the machine shop bored the cylinder.
It ran for a week perfectly and then steam came out the right side exhaust (separate pipes).

Took it to the machine shop. I said sleeve all of em.
He sleeved the one cylinder, it did it again the next cylinder.
I was super pissed and let him have it. He said bring me another block.
Since then haven't had any problems.
« Last Edit: April 10, 2019, 02:11:07 PM by Rattiac »

28chevyguy

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Re: turbo V6, blew head gasket .. I think .
« Reply #2 on: April 10, 2019, 02:34:42 PM »
It is 191 ci  ,  3.1 mpfi ,, Turbo grand prix McLaren edition .    Just talked to another machine shop who said he sees stuff like this happen a lot with the tuner guys ,  apparently he thinks the gasket is good enough to hold compression but was "lifted" under boost allowing the coolant to become pressurized .    I sure hope its just a gasket replacement deal .   

for right now , its off with its head haha

28chevyguy

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Re: turbo V6, blew head gasket .. I think .
« Reply #3 on: April 10, 2019, 02:58:08 PM »
woo hoooo looks like I just smoked the head gasket !! man im starting to get off easy these days... #6 was egg shaped on the gasket .

now im going to harbor junk and buying a electronic torque measuring tool if they have them   seems like the bolts came out aweful easy.   Tough call with the TTY bolt , it says 45 ft lbs with addition 90 degree turn.... guy at machine shop was estimating that to be about 65-70 ft lbs total...  im rusty with the car havnt messed with it in years but I remember trying to run a higher torque spec than stock since the custom turbo kit and the devastating boost this turbo makes.  holset hx35 hits hard .    Everyone recommends ARP head studs but id rather blow the gasket then a hard part .

chopper526

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Re: turbo V6, blew head gasket .. I think .
« Reply #4 on: April 10, 2019, 05:21:15 PM »
That's good news, it sounds like you got lucky...sort of :o Keep us posted!
Tighten it up til it strips, then back it off a quarter turn

EDNY

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Re: turbo V6, blew head gasket .. I think .
« Reply #5 on: April 10, 2019, 05:37:20 PM »
I just put a Jeep engine together with the manual giving initial torque then 1/4 turn ???.  Shopped around and located straight up torque numbers! ;)

Have the HF torque cube (under $30) and as with my ACDELCO torque cube just use it to set my click torque wrench.  When the torque wrench clicks...just look at the torque cube to determine at what poundage it clicks - then disregard the torque wrench settings and adjust until it squares up with the torque cube.

You can also use the torque cube to manually calibrate the torque wrench...some disassembly required :) :)

33 Chevy 5 Window, 34 Chevy 3 Window, 37 Chevy 4dr sedan

28chevyguy

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Re: turbo V6, blew head gasket .. I think .
« Reply #6 on: April 10, 2019, 06:57:28 PM »
That is genius!!!  Will do that for sure  thanks !

 


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