Blueman33

Several times I have heard reference to 951's blowing head gaskets, but I don't see that many posts about it.

I'm curious, have YOU ever blown a head gasket? How prevalent is this problem?

David Floyd

If the car is stock you should have no problems.

If you turn up the boost without addressing the increased fuel needs, well...... that's when you blow a gasket

Try the search feature, I think you will find plenty on blown headgaskets.

Danno

I've destroyed plenty! Gotten to the point where I can replace one in under 6-hours (typically 8 to replace all hoses & seals). I've also known other tuners who've blown several wide-firering gaskets on the same car within weeks. It's typically not blown from combustion-pressure, but burned from the intense heat of detonation. Which was caused by improper air-fuel ratios (lean). I wrote up an analysis here:

<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=18&t=002511" target="_blank">Headgasket Dissertation</a> referenced in this thread:<a href="http://forums.gururacing.net/viewtopic.php?t=43" target="_blank">GURU Ultimate Headgasket</a>

badass951

My car has blown it's stock head gasket in the past, and over a month ago now I blew the replacement wide-firering head gasket. I changed nothing from when the previous owner sold me the car, however that seems to have been my mistake. In Florida where I bought the car it ran incredible. When I got it back to Pennsylvania the car was detonating. For three weeks now I have been waiting for my new head and gaskets. So frustrating!

ian

Yep I blew one, in a huge way, must have been a full inch whole in the damn thing....

I saved it just because, it was something good to keep....

then when I put it on the dyno to try and tune the a/f the guy running the dyno said I was so lean I was luck that porsche made such stout internals, he said with a honda I would have blown a piston out or worse....

Tuning is your friend, bad tuning, or bad chips, or bad gas, or many other things will work against you.....

Danno

"My car has blown it's stock head gasket in the past, and over a month ago now I blew the replacement wide-firering head gasket. "

Don't just replace the headgasket, find out WHY it blew in the first place. The blown gasket is just a symptom of something else that's wrong in the car. The detonation you're getting is a clue that the air-fuel ratio is too lean. This could be due to a mis-adjusted AFM, a single clogged injector, too-hot plugs, a failed FPR, dampener or fuel-pump, or vacuum leaks, etc.

badass951

Danno - I did not replace it. What I meant was the previous owner blew the gasket and replaced it with a wide-firering gasket. Apparently the previous owner did not do anything to fix the issue and just replaced the gasket.

Here is a question though...

Why did I start to run lean in PA, but in Florida the car was running perfect. Wouldn't the air be less dense in PA, causing it to run more rich?

ian

Less dense with a turbo shouldn't matter as much, you should still generate the same amount of boost, this is why turbo cars still run well in mountian or airplane applications....

i would think though that the cooler air in PA would be helping you out, I would think that there is some other problem, maybe a fuel delivery issues? dirty injectors? vac leak?

I would look at some dyno time to try and see what your a/f ratios are doing ASAP after you get the car togeher....

Danno

Sorry, I didn't mean to imply that you were at fault for the headgasket.

Wouldn't the air be less dense in PA, causing it to run more rich?"

Air-density differences wouldn't be significant enough to cause a big-enough shift in air-fuel ratios to cause outright detonation. It sounds like you don't have enough fuel somehow.

"Why did I start to run lean in PA, but in Florida the car was running perfect."

Typically problems can surface over time. One quick check is to pull your plugs and see how they look. They should all be similar looking, and if you had an injector that was going lean, you can definitely tell which one it is from the plugs.

Then check your vacuum lines. If there was a leak in one near the FPR, then your fuel-pressure won't increase enough with boost to keep up with the extra air. At idle, you should be seeing around 12-18 in.Hg of vacuum. A freshly-rebuilt car can get 20-22 in.Hg of vacuum. If you are below 10, then either you've got a really worn-out engine, or there's a vacuum leak somewhere.

Another test is your boost-pressure. The dash gauge can be off due to oil clogging the vacuum line leading to the KLR. Hook up an aftermarket gauge and verify that you have stock boost 10-11psi max in 4th and 5th gears around 4000rpm. If you have more than stock boost with stock chips, you'll run lean for sure.

Also check your fuel-pressure. An FPR or dampener that's failing will mess up your fuel-pressure. Should be 38.5psi @ idle with the vacuum line disconnected.

AFM could be another issue. Measure the voltage coming on the DME #7 green/red-stripe wire. Idle should be 0.79-0.85v or so. At 3000rpm in 3rd-gear at steady-state speed on level ground, it should be in the 2.0-2.2v range. If your AFM is out of this range, there could be some stiction in the flapper-door pivot that's making it stick perhaps?

As you can see, it's not a simple, single-source issue that can be tracked down easily.

User 41221

Could quality of gas be an issue here? Seems to me, PA has lots of lower octane, methanol added blends, whereas the gas in FL seemed to be better.

This is just an observation based on driving through both places numerous times, and not a scientific rendering.

Regards,

SimonK

I blew mine on the autobahn at 150mph. It was mainly age - 120K miles. The cloud of smoke was unreal! It blew simply as I haven't paid enough attention to temperature guage. When driving that fast - our cars get very hot very quickly - watch that temp guage in the summer!

Matt Sheppard

Anyone NOT blown a headgasket?

aka 951

22 psi bonzi runs (TO4E) combined with 91 octane and my old 86 blew one

OriginalSterm

I've noticed I run a bit on the lean side too. At a recent tune-up, #2 and #3 cylinder plugs were ghostly white, indicating I was a bit too lean. Could this be from the chips I'm running, or a head gasket problem, or an intake manifold problem? I'm running Huntley chips, anyone know if they are prone to a lean shift over time? I'd hate to blow a head gasket due to something I could have prevented.

David Floyd

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> Anyone NOT blown a headgasket?
</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica"><img border="0" alt="[hiha]" title="" src="graemlins/roflmao.gif" /> I have changed a few headgaskets but never blown one (knock on wood)

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> I've noticed I run a bit on the lean side too. At a recent tune-up, #2 and #3 cylinder plugs were ghostly white, indicating I was a bit too lean. Could this be from the chips I'm
</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Could be the uneven flow of our intake manifolds, have you been to a dyno to dial in the a/f ratio ?
<img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />