Why does the head gasket blow?

[The Swede]

Hi all!

Just wondering why the head gasket blows after you let the throttle off?

Or does it blows earlier and the engine takes care of all the water and then when you let the throttle off all the smoke is coming?

For me.... i have it on video.... let the throttle off just after the 1/8 mile and we can see the white smoke at the 1/4 mile.

I have seen more of these turbocharged engines "blowed" after the line.

Have all the good stuff in the engine..... 7.13@160 1/8 mile..... 21PSI with racing gas and methanol, Joe Lubrant race chip.

Engine is out and waiting for coming in pieces soon.
Just gotta have to find out why it blowes...........

 

[BlackBandit]

I don't know about the head gasket thing, but is your speed in the 1/8th mile in Kmph? For a second there I thought, "Holy $#!^ that's fast!" Hope someone can answer your headgasket question.

 

[Razor]

It is my belief head gaskets blow due to detonation. When you increase cylinder pressure, it doesnt take much detonation at that power to POOF the gasket.

Its all in the tune....

HTH

 

[MistaScott]

Mine blew due to a cracked fuel pressure regulator vaccum line .. anything that screws with the air/fuel mixture... result is major knock and BOOM. Could be not enough octane in the fuel or in my case, not enough fuel.

 

[The Swede]

Ooopppss... sorry guys, my speed is 100mp/h at the 1/8 mile.

Razor and MistaScott:

I have no problems with the tuning, tuned the car in before the race with Turbolink and also raised the fp. to be safe.
Also has knockgauge in cockpit, didn't notice anything on it during the ride.
VP112 octane and SMC alky together.

Any one that can answer why the white smokes comes when you let the throttle off?

 

[gnsrule]

Under throttle, the cylinders and intake are under pressure actually blowing steam into the cooling system. After you let off, slamming the tb closed, the motor now goes into max vacume therfore pulling coolant into the cylinders.
Hope that helps

 

[The Swede]

Originally posted by gnsrule
Under throttle, the cylinders and intake are under pressure actually blowing steam into the cooling system. After you let off, slamming the tb closed, the motor now goes into max vacume therfore pulling coolant into the cylinders.
Hope that helps

Yes, thank you!
That was the same i was thinking about.

 

[turbov6joe]

After a wall of blown HG's to look at and remind myself of what NOT to do, I've come to the conclusion that unless you have a catastrophic amount of detonation and the gasket blows BIG time (multiple cylinders), they sustain a little damage here and there then let go after repeated abuse. The bottom line seems to be that the stock heads (headbolts) cannot keep the heads planted under extreeeeme cylinder pressures and they lift thus eating away at the gasket material.......BOOOOM! At 20+ psi it only takes a little bit of detonation to eat away at the fire ring and the graphite composite material untill the sturdity (my word) and overall rigidity goes to hell. I swear that once the factory seal is broke, you'll never get them to seal correctly again....that is unless you go to a stage or Champion stage style head with the additional head bolts to hold'em down. I'm almost convinced that the longer you can keep the head on with some regular driving, the better your odds will be that they're glued down on there due to repeated heat cycling. Look at a high mile motor with say 80k miles, the headgaskets seems to never let go unless the motor is really detonated bad.

 

[Razor]

Originally posted by The Swede
Ooopppss... sorry guys, my speed is 100mp/h at the 1/8 mile.

Razor and MistaScott:

I have no problems with the tuning, tuned the car in before the race with Turbolink and also raised the fp. to be safe.
Also has knockgauge in cockpit, didn't notice anything on it during the ride.
VP112 octane and SMC alky together.

Any one that can answer why the white smokes comes when you let the throttle off?

There is a lot of information that turbolink sometimes doesnt pickup due to its frame rate. Also your tuning using the O2 sensor as a reference. You cannot rely on the factory O2 when using 112 leaded fuel. This is a reason for EGT meters to get a handle on how high cylinder temps are getting. You can be at 1800+ degrees on an EGT and read 760 for O2's..you cook the motor high enough, you can blow anything. And as stated, a lot of times the detonation over time chips away at the seal.

You havent addressed other things like deck surface, head surface, bolts, ignition system, fuel system, timing, etc? Any problem with those..and Poof goes the gasket.

White smoke = oil?

If the motor is assembled properly, and the tune is correct..you will not blow the gasket... if that was the case, everybody on the list would have blown theyre gaskets.

Lastly, is it the same gasket that always goes? Same cylinder? this may lead you to your answer.

HTH

 

[The Swede]

Guys,

I have the ARP bolts.
When i imported the car from US it had this grooves in the heads and this NEW Fel Pro gasket style, there was a small leak of water from #6 so we openend the engine and checked the grooves....couldn't find any wrong with them so we put on a new set of gaskets.
After a few full pedal testings water where spraying heavily out from #1.
We decided to fill the grooves up with cheramical metal and mounted new stock gaskets.
After this it looked like the engine was OK, but in the last race for the season here it blow up.

In Sweden we don't have leaded race fuel, not allowed here so the VP 112 is unleaded.

The white smoke coming from the engine where water in the cylinders, don't know yet where it blowed, gonna open the engine this weekend to find out.

Engine where almost "new" when i got it here, all machine work and mounting where done at a good speedshop in Plainfield IL, Precision Engine Rebuilders.

The fuel pressure where set at 48PSI.

Fuel pump is a Walbro.
Stock ign. system.

Could there be a sulotion to make a coppergasket instead?
I have a friend here that custom make them.

 

[5ltretr]

I think the fuel pressure might be to high, did you set it to 48psi line on?

 

[The Swede]

Originally posted by 5ltretr
I think the fuel pressure might be to high, did you set it to 48psi line on?

Vaacum line off.
After reading the Turbolink..... i think it was just perfect on the O2 reading but i wanted to be safe so i think i turned the FP up 1-2PSI don't remember excatly now.
Could also been 47PSI, not 100% sure.

You mean that the head gasket blows if i go up 1-2PSI?

Have raced the TTA in that way for 4 years and no problems.
The TTA had the head gaskets changed for 6 years ago when it arrived to Sweden.

 

[turbosam6]

I could be wrong here, but I believe alky has less octane than 112, so you may have been lowering your octane with it. No, the fp being too high won't cause gasket failures. It'll just cause a rich condition. Sounds like either you were under octaned, or the head gasket seal isn't very good, maybe because of the o ring grooves?

 

[The Swede]

Originally posted by turbosam6
I could be wrong here, but I believe alky has less octane than 112, so you may have been lowering your octane with it. No, the fp being too high won't cause gasket failures. It'll just cause a rich condition. Sounds like either you were under octaned, or the head gasket seal isn't very good, maybe because of the o ring grooves?

Thank you for your answer turbosam!

I'll vote for something to do with the sealings on the head gaskets, hope i have some time over this weekend to open the heads and have a look what happend.

Methanol has a cooling effect on the engine, and i use the best Methanol on the market.
The alky/methanol kit is approved to do well with pumpgas and racechip, i used racegas and alky to be safe.........
The alkykit is the latest model from SMC and i run it on full spraying at low piont.

I haven't seen anything bad at all during the ride on the knock gauge.

BTW: The time i have on the car is on a non prepered track (airfield) and this was the first time on slicks for me with the car, (only 1 run, then it blowed).

I have also been dragracing for the last 20 years so i do know how engines work.... just curios in my thread why the white smoke came after the throttle let off......

In my passed we raced with a Morris Minor (looks like a beetle) and where down into the 9's with stock heads, mechanical cam, 1 carb. and a Chevy 302".
The car was a showstopper.....
Please have a flashback 20 years ago....
http://medlem.spray.se/nostalgi68/ sorry for the swedish but enjoy the pics!
We built the comlete car in our garage.

 

[Razor]

The SMC alky kit is not methanol compatible. the pump will not handle methanol. Per Steve at SMC.

Open you tank and look inside, what does the surface of the pump look like?

Uffe.. this faster car blows up faster. Something is happening, it is probably simple..you are overlooking.

Maybe the chip? Electronics can cuase this.

Find out what cylinder blew.. post back.

I had a friend that was blowing head gaskets becuase of a bad check valve.. the one that goes to the EGR.. it was letting boost through and pulsing the EGR cuasing the motor to go lean. This is an example where fuel pressure was set correctly , yet the car blew the HG. Start checking stuff..its an 18 year old car..

HTH

 

[The Swede]

Huh? The SMC doesn't like methanol?
What shall i run in it then?
I haven't looked into the tank since i don't have the car at my home.

Engine is open now, blowed on #1.
Found the rest of the HG in the lifter gallery.
I also saw that the holder for the..... what is the name? Beside on the crank where you get the impulses for the ignition... crank trigger?the holder is made of aluminium and one of the brackets are cracked.... approx. 3mm. wrong.
Earlier owner did some "easy fix" on it screwed a bolt through the bracket, will get a pic later of it since i run out of battery in my cam.

2 pics of the gasket: blowned gasket, http://www.tacs.nu/forum/download.php?id=1740

and why aren't the gaskets excatly round around the cylinders? http://www.tacs.nu/forum/download.php?id=1739

 

[The Swede]

Here is the pic of the bracket:
http://www.tacs.nu/forum/download.php?id=1742

I'll guess that this could be one part of why it blowed the gasket?

I mean: When the bracket is bended like you see on the pic, the impulses becomes wrong, right?

 

[striker_29]

Damned if I know Uffe, but I'll take it to the top for ya

 

[Razor]

Originally posted by The Swede
Huh? The SMC doesn't like methanol?
What shall i run in it then?

You run a less corrossive type of alcohol. Denatured alcohol, isopropyl alcohol. And must use lubricant due to the style of pump.

If your crank trigger was bad..it would shut your engine off.

I would look at fuel system, vacuum hoses, emmissions related items.. etc.

The gaskets are made that way..its how it is. Check the cam and make sure the lobes are not damaged. Sometimes a lobe gets damaged and will cuase the gasket to blow. Bad injector can also cuase this.

You need to start looking at everything related to cylinder one. From coil pack, cam, springs, injector, spark plug, etc

HTH

 

[The Swede]

Razor et. all!

The crazy swede might be crazy but hi is not stupid, i use lubrication for the SMC, i think it's callad Lubron.... by klotz, special use for mixture with nitromethan and methanol.

I'm more suprised that the SMC kit doesn't work with methanol, but i will get the right stuff for it later.

Crank trigger aint broken, just hanging in wrong position if you have a look at the pic.

Haven't found anything wrong with fuel system, injectors (matched MSD 50's) vaacum hoses or anything else.
Cam was just fine.

But i did check the surface on the heads (just machined in USA) and they where not straight.

I wen't to one of my friends that owns a Pro Stock team and he couldn't just beliwe why the grooves are in the heads? Me nieghter i tould him.

After a long discussion with him i diceded that i'm gonna custom made copper gaskets and have the O-ring groove made in the block.

Next step is Stage2 with more head bolts but that is way to expensive for me.

We are just so strange for this tourque sequense on the heads..... 3 times? That must make the HG to be like an arrow under the head.

Thank you all for taking your time and giving tip for me!

BTW: Do you have any shop over there that has copper gasket for stock block?