can heads still lift under load without detonating?

[Nick Micale]

i have seen this before myself. I do believe that the heads do lift in some way or another. I generally see this happen on the center cylinder. I think that due to the 8 bolts per heads allow the head to flex and lift in that area. .........................

In my 20+ years of working on these turbo Buicks, I have replaced many hundreds of blown head gaskets, lots of these from detonation, but in my humble opinion, many others from too much cylinder pressure.

My thinking is like what is said above. Maybe if the term "deformed" is used instead of "lift", that would be more easily accepted?

The most common place for a gasket to fail is out the top or bottom of the head where bolt/stud spacing is greatest. If it fails mid-way between the fasteners, does not seem to me that this is NOT a lack of clamping force, but too much cylinder pressure pushing, lifting, deforming or doing whatever you want to call it.

My heads are torqued to 70 ft-lbs and have never blown a head gasket in almost 1000 runs. Due to other issues, I have trashed a few pistons. This shows me if clamping force was not sufficient, even with 6 bolts per cylinder instead of 4, I would have blown a head gasket.

Another of my opinions is that lots of failures are due to lack of re-torquing, after assembly, break-in and then a few heat cycles. If no more than stock boost is ever going to be applied, then maybe re-torque would not be necessary - but simpler to be safe than sorry. :biggrin:

 

[bison]

In my 20+ years of working on these turbo Buicks, I have replaced many hundreds of blown head gaskets, lots of these from detonation, but in my humble opinion, many others from too much cylinder pressure.

My thinking is like what is said above. Maybe if the term "deformed" is used instead of "lift", that would be more easily accepted?

The most common place for a gasket to fail is out the top or bottom of the head where bolt/stud spacing is greatest. If it fails mid-way between the fasteners, does not seem to me that this is NOT a lack of clamping force, but too much cylinder pressure pushing, lifting, deforming or doing whatever you want to call it.

My heads are torqued to 70 ft-lbs and have never blown a head gasket in almost 1000 runs. Due to other issues, I have trashed a few pistons. This shows me if clamping force was not sufficient, even with 6 bolts per cylinder instead of 4, I would have blown a head gasket.

Another of my opinions is that lots of failures are due to lack of re-torquing, after assembly, break-in and then a few heat cycles. If no more than stock boost is ever going to be applied, then maybe re-torque would not be necessary - but simpler to be safe than sorry. :biggrin:

I agree with Nick. The intake side of the head is relatively thin in the combustion chamber area without the reinforcement of the spark plug. I see the most problems in that area. Detonation caused almost all of the failures ive seen.

 

[Razor]

You have the straw that broke the camels back scenario. Where you've been beating the snot out of the motor for a long time then one day at low boost "poof" there goes the gasket. Cometics for example let go a little at a time vs a graphite that blows cleanly.

Back pressure like sticking a banana in your tailpipe will blow a head gasket at low boost. This happens when you try and run high boost with stock exhuast and stock cat.

When you detonate the cylinder pressure spikes along with cylinder temps. If you look at EGT's on a motor that is detonating you'll see the numbers increase dramatically. That pressure has to go somewhere. Down through the rings, or out through the HG.

Guess its like chipping away it until one day pooof.

Pushed gaskets without fire are typically fastener/installation issue. Burnt gaskets.. that ones easy.

 

[qwknuf6 jr]

No, I said, my heads don't lift at my tune and boost levels. You said, "that's incorrect". My question again is, how do you know this???

Incorrect again , see your 1ST post and the first reply to the OP question .

(Quote = Heads don't lift. END Quote)

You are wrong on both accounts , your heads do lift under boost as do every other stock 3.8 turbo buick v-6 .

May be you should think before you post

 

[Phoneguy]

Not having your block trued and the correct finish done before installing Cometics will cause this as well. I could not keep the heads from lifting on mine. Ran fine until about 20lbs.

Bryan

 

[Fast4Ward]

reason why i asked this questions is, i've got a car with some older mods.
its got the o ringed heads...or should i say grooved heads with arp studs/sealer and the 1007 gaskets.
unfortunatley getting a electronic speedo to work properly has cost me a blown gasket but i'll say lifting a head...only because of this...a few times i've taken it out and pushed it to 18-19# of boost with none of the 3 knock sensors working as the tt chip and gm ecm needs to reference mph before it pulls timing and see knock. i kind of knew but went agains my better judgment not to mess with it until i got all the answers...i'm with stupid:redface:
i beat on it for a while with 15# of boost without the speedo and knock gauges and was fine until i decided to turn up the boost ..anyway
so here's what's happening, the compression is 155+ on all cyls but i didn't check it before dropping in some seal tabs.
because its not dropping any coolant now and the rad is not bubbling over,
do you think i'm lifting the head and blowing a passage past the groove wire?
i have now thrown away that good for nothing except eye candy 8 gauge gnx panel and gone back to stock cluster with just 3 gauges on the side and will be road testing the car again this time with everything working like it should.
sorry to make it so long guys...bed time.
PS...no coolant in the oil...i check it often.

 

[TurboDave]

In my 20+ years of working on these turbo Buicks, I have replaced many hundreds of blown head gaskets, lots of these from detonation, but in my humble opinion, many others from too much cylinder pressure.

My thinking is like what is said above. Maybe if the term "deformed" is used instead of "lift", that would be more easily accepted?

The most common place for a gasket to fail is out the top or bottom of the head where bolt/stud spacing is greatest. If it fails mid-way between the fasteners, does not seem to me that this is NOT a lack of clamping force, but too much cylinder pressure pushing, lifting, deforming or doing whatever you want to call it.

My heads are torqued to 70 ft-lbs and have never blown a head gasket in almost 1000 runs. Due to other issues, I have trashed a few pistons. This shows me if clamping force was not sufficient, even with 6 bolts per cylinder instead of 4, I would have blown a head gasket.

Another of my opinions is that lots of failures are due to lack of re-torquing, after assembly, break-in and then a few heat cycles. If no more than stock boost is ever going to be applied, then maybe re-torque would not be necessary - but simpler to be safe than sorry. :biggrin:

Deformation or distortion, I can live with those terms. Lifting? I still can't buy.

 

[BlownV6]

Deformation or distortion, I can live with those terms. Lifting? I still can't buy.

How bout I send you a discount coupon so you can buy "lifting the heads". Maybe look at it this way!! When torquing rod bolts , you either torque them to a certain value , or you do torque angle , or the recommended way is to do bolt stretch method. All of these are stretching the bolt to a certain load factor and recommended stretch value of the bolt. Now this on high dollar rod bolts , so imagine the stretch on a cheaper grade head bolt. Torquing the heads is doing the same thing - stretching the bolt to a certain value. This is all well and good until you push cylinder pressure past what those bolts can hold without slightly stretching enough to release some of the clamping load on the gasket which is at that point also seeing this excessive pressure against it. So without the proper amount of clamp load on the head gasket the combustion pressure either sneeks past the gasket seal or it pushes the gasket out of its way. Thats the way I see it!! Mike

 

[TurboDave]

How bout I send you a discount coupon so you can buy "lifting the heads". Maybe look at it this way!! When torquing rod bolts , you either torque them to a certain value , or you do torque angle , or the recommended way is to do bolt stretch method. All of these are stretching the bolt to a certain load factor and recommended stretch value of the bolt. Now this on high dollar rod bolts , so imagine the stretch on a cheaper grade head bolt. Torquing the heads is doing the same thing - stretching the bolt to a certain value. This is all well and good until you push cylinder pressure past what those bolts can hold without slightly stretching enough to release some of the clamping load on the gasket which is at that point also seeing this excessive pressure against it. So without the proper amount of clamp load on the head gasket the combustion pressure either sneeks past the gasket seal or it pushes the gasket out of its way. Thats the way I see it!! Mike

OK, I'll fall in line with everybody on this one. I just wish that somebody over the last many many decades of automotive history would/could have taken some kind of video of a head actually lifting. After all, we've seen the video taken inside a firing cylinder, certainly somebody could have shown this head lift activity.

 

[BlownV6]

OK, I'll fall in line with everybody on this one. I just wish that somebody over the last many many decades of automotive history would/could have taken some kind of video of a head actually lifting. After all, we've seen the video taken inside a firing cylinder, certainly somebody could have shown this head lift activity.

If you watch NHRA dragracing on TV you usually can this happening with someones Top fuel car somewhere along the line. When you see slow motion shots of the cars and you can see fire coming out between the heads and the block that exactly what is happening. It only takes a few of these combution cycles before the head gasket is melted away and fails completely.
A couple of weeks ago Pat Dacon from here in Dayton , in the first round when he hit the throttle you could see fire shoot out from under the whole head on right side. I told my wife "they forgot to torque that head down" and sure enough we found out later that was the problem. Mike

 

[xrunner123]

Here's a picture of head lifting-

 

[Grumpy]

Lifting? I still can't buy.

I call it "dancing" .. Like the main caps do when ya push it a little

 

[qwknuf6 jr]

And the head gaskets SCRUB back and forth .

Mark

 

[BlackBandit]

I'm sure more blown head gaskets are atributed to lifting than necesary as most are probably due to poor tuning. In fact, a pressure spike due to detonation (aka a crappy tune) could exibit the same signs as lifting/deforming due to to much pressure since it creates the same environment (to much pressure.) I guess what I'm saying is detonation can lift/deform a head and blow a gasket without blowing the fire ring just like to much pressure on a good tune can and is probably WAY more likely. That doesn't mean the head didn't lift deform, just means people still don't know how to tune. It's just that saying "I lifted a head" doesn't make you sound like a moron where as "I blew a HG because I don't know how to tune" does. And for anyone that disagrees I just tossed a set of head gaskets with perfect fire rings and chunks of graphite missing that I created using detonation. I also think Nick is right about people not doing retorques being part of the problem as many think the felpro PT gaskets mean that they don't need retorque in performance aplications.

As a side note to Cme2fly do your data logs show preignition? Not saying you didn't lift due to good tune cylinder pressure, just wondering as our knock sensors don't pick up preignition.

In summation. It's possible we're seeing more of these types of failures because the TB comunity is making more power as a whole than ever before due to new technology being available and so the way headgaskets are failing is changing some. I still stand by my idea that the cause is still the same though. That of course being lack of tuning ability.

 

[BlackBandit]

I suppose I should say lack of tuning ability and lack of engine assembly knowlege.