F*#$ing Headgasket!

[TimZ]

TimZ' date='

 

I tune to AFRs and detontation. Wind timing back to whatever doesn't ping, get AFRs right, then wind timing back in slowly until it pings, then back off a touch. Done.

 

Sound reasonable?

 

Dave[/quote']

 

Yes, that sounds reasonable. I do like having EGTs as well - it's a bit easier to tune the timing with this measurement. If you back off the timing too much, you won't notice by checking for ping, but you will see the EGTs rise.

[thehelix112]

Good point. But you'd have to be backing it off significantly to see a major rise in the EGT yes? A couple of degrees would be ok?

 

Dave

[Guest 73Turbo240z]

 

from timing cover to firewall, 1 through 6...

 

cyl 1:

 

cyl 2:

 

cyl 3:

 

cyl 4:

 

cyl 5:

 

cyl 6:

 

theres the gasket, 1 through 6... looks like 3, 5, & 6 took the worst of it, which is odd, cause if it was fuel related, the injectors are batch fire 1-3 and 4-6, which the failure areas contradict that theory.

 

pulling the head, the torque on the studs was good, so i've ruled out lack of torque as well, best i can figure is that my tune was no good and my dumbass should have been driving around w/ the LM1 plugged in and reading, mechanically we verified timing being spot on, though i need to figure out what a very conservative and safe starting point would be for ignition timing this time around, and re-tune from square one.

 

HKS 2mm headgasket is on the way from courtesy nissan, should be here in 2 days, so in the mean time i'll pull the front cover and start re-setting things up as much as i can.

[thehelix112]

Wow, #3 really not happy there hey. Another thing I assume you checked was that the ignition interface between the megasquirt and the engine was correct. Ie, the megasquirt was getting pulses at the appropriate time and delivering spark at the appropriate time?

 

You put a timing light on it and verified that against the MS value is what I'm saying I guess.

 

Dave

[BRAAP]

First off, I’m sorry to see this happen to you. Set backs like this can be discouraging, but don’t let it get you down. I’m sure you’ll get to the bottom of this failure an get it fixed.

Back to the details of this situation.

Very interesting. In looking at cylinder #3 and the way the gasket just pushed out, it didn’t just blow out the combustion ring, but pushed that ENTIRE portion of the gasket out from between the head and block deck surface, indicating the head lost its clamping pressure allowing the gasket to just “push out” at the most convenient location. Hmmm… Head studs and it still just pushed out. I honestly don’t think ANY head gasket, no matter what brand, would’ve remained in tact if the head looses its clamping pressure.

Also of note, at the 10:00 position of cahmber#3 the gasket was letting go as well.

Looking at #4, at the 2:00 position was also squishing itself out. #5 also at 10:00.

#6 has the classic signs of plain old fashioned detonation, the deformed fire ring, the “burned” out portion where it actually did let go, etc, not so much of the head losing it’s clamping force.

In my best guess looking that evidence presented, you definitely had detonation going on and also the head lost its clamping pressure for one reason or another, (maybe due to the detonation and excessive cylinder pressure? Rod bearings for those cylinders “might” show signs of being squished out if the cause was extremely severe cylinder pressures lifting the head). Other causes could be deck surface and head surface not being truly flat. Also, the Fel-Pro head gaskets prefer to be installed COMPLETELY dry!

First off, the Detonation needs to be dealt with and secondly, you need to find out why the head either lifted or just plain lost its clamping force and allowed the gasket to “push out”.

Have you thought about “O”-ringing your block/head? This doesn’t fix the detonation problem or the head lifting problem, but it does allow the gasket to have a better chance of surviving the harsh pressures and heat environment of a radically boosted engine.

 

 

 

As an aside, here is a good primer to installing head gaskets. I typically stay out of these discussions here on this forum as there are some guys with all the “theoretical” and book based knowledge in the world, and also those old timers that can’t seem let go of the methods used for those old gaskets made in the 1950’s and trying to talk to them about why their modern head gaskets continuously fail is like beating your head against a brick wall. Not only does the wall remaining standing, but it HURTS! Any how, those times and 1950’s gaskets are gone. All the books in the world don’t make up for first hand experience. Put a wrench in Einstein’s hands and I’ll bet his cars would fall apart.

’73Turbo240z, None of my comments or accusations printed here are intended toward you in any way shape or form. It just so happened that your thread is the thread that I decided to let loose my inner feelings on the subject of head gasket installation. My opinions stated here are merely for educational purposes for others that may be reading this thread.

 

Gaskets really aren’t MAGIC and don’t need any KY jellies, paints, “tacks”, glues, Lubes, Voo-Doo dolls, magic potions, Psychics blessings, etc to install and to keep, not only the chambers, but the water and oil transfer ports “sealed”.

For Felpro Printo-seal gaskets and the Graphite faced gaskets, use 99% rubbing alcohol, or something equivalent, to get rid of ANY and ALL oils, etc, from the head surface and the block deck surface and these gaskets will hold up just fine, unless you are abusing them with detonation or warped or uneven surfaces from using those abrasive buffing discs, (that is a whole nother thread in itself… Don’t get me started…LOL). You want NO oils, water, dirt, contaminates, whatsoever on the head and block surfaces. No SILVER paint, no antisieze etc. I have seen lots of these ludicrous methods used. If the gasket is going to let go, none of those “super-whiz-bang” “tacks” and glues are going to help squat, and the lubes only allow the gasket to move around between the head and block surface from the varying heat cycling and will eventually fail due the gasket being “rubbed” down. If the gasket has a factory type lube already on it, i.e. Graphite style gaskets, then they were designed that way, so don’t try and make that design better by adding your own special “trick”, “guck” or “magic”. It WON’T help.

The dry gaskets such as the Fel Pro, are engineered for just that, DRY! In theory, the DRY head gaskets should work better on head block materials that are the same, i.e. both being Aluminum, or both being Iron as the head and block will grow at equal rates and amounts. Graphite gaskets came about in an effort to allow the aluminum head and iron blocks a chance to grow and expand at their respective differing rates and amounts. The jury is still OUT on whether it really works or not, as no matter what manufacturer uses this combo, those graphite gaskets still fail the same and just as often as the dry gaskets. Half dozen one, 6 the other. For my N/A engine build ups I’ll stick with Fel-pro, unless of course, the customer specifies something else.

If you prefer a particular head gasket and it works great for you, then by all means, keep using it. The Fel-Pro head gaskets sure get a bad rap on this forum and I’m not so sure it the installer fault or other issues that are causing, but Fel-Pro gets blamed for it. I won’t condone their usage, but for all the N/A engine I have ever built using them, they are all doing great.

[v80z]

Hey Man

 

While you got that thing disassembled do you have any more material on the head to get it decked? May check the plane on the block as well. At least 3m that block. Looks like 1256 are pig rich. and 34 were pig rich as well until some event. I always found the inner cylinders carried more heat that the outer 4. But plenty of black deposit on all until some event triggerred 3 4 was soon to follow. Definate High cylinder pressure.

 

How much cam advance and ignition advance. Only speaking from experience. Had mine advanced so that the combustion was actually impeding the piston travel. Trying to get to the naked edge and beyond.

[80LS1T]

Does the L28 have any aligning dowls on the block to properly hold the head gasket in place? It doesnt look like? Was the block machined and then were they removed and not put back in? Cause if that gasket wasnt lined up properly when torqued down it could blow out real easy....

 

 

Guy

[Tony D]

I'm going to weigh in on the side of Braap on this one. I ended up going to a (if you can believe this) a 5-Day Seminar sponsored by Fel-Pro's Parent Company. This was in conjunction with the roll out almost 10 years ago of a specialized gasketing compound they were introducing as an OEM item on large Stationary Power Plant Diesels. I didn't think there was so much to be said about gaskets, but suffice to say we spent a day on major types of gaskets they sold, as well as the marketing stuff that always makes it's way into these kind of things.

 

Anyway, the Print-o-Seal gaskets are (were at the time) the new Miracle Gasket, and they made it very clear that

1) No Compounds Were to be Placed on Mating Surfaces.

2) Surface finish must be compatible (forgive me if I forget the number, but it wasn't a mirror...)

3) Proper Torque Sequence Must be Followed.

 

There was a lot of stuff about why gaskets fail, these were the top three.

 

Looks to me like there is some detonation, and I would NOT O-Ring until you get that in hand! All an O-Ring job will succeed in doing is breaking your piston skirts FIRST, then your ring lands, and then your piston crown. Be GLAD your Fel-Pro failed, because if it kept that detonation pressure IN the cylinder, the ONLY place it has to go is towards the piston---and that means breakage.

 

The 2mm Head Gasket is going to lower compression, so this problem may be masked a bit.

 

In my case, I used an N42 Block, and an N42 Head with a Fel-Pro Print-o-Seal Head Gasket when I assembled my Blowthrough Turbo Engine in 1987. That engine has seen countless hours of 17psi boost levels. i worked up to that point, first starting at stock boost, then 10, 12, 15, 17.... Tried a few passes at 21 but knew the T3 was already running to it's limits. So I turned back and ran 17 daily commuting and would dial back to 14 during track days during the SoCal heat.

 

Thusfar (knock on my head) that Fel Pro is still in there and not leaking. I had some ping due to some transitional lean issues dealing with modulator rings being the wrong size after a resizing of the plenum in 1994, but even then, nothing serious.

 

I have overheated it during a cooling fan failure on the 60 Fwy in Rush Hour, run it lean due to a boost pump failure once, and generally abused it but thusfar it's holding it together. When it comes out and I tear it down, I'm curious to see what happened during all that abuse over the years.

 

I did run a tad on the rich side (as most carb turbos do) to forestall no detonation, and you may be well advised to do the same. When detonating, something will fail.

 

My preference is it's the head gasket, and not my pistons!

 

I digress...

[Guest bastaad525]

Does the L28 have any aligning dowls on the block to properly hold the head gasket in place? It doesnt look like? Was the block machined and then were they removed and not put back in? Cause if that gasket wasnt lined up properly when torqued down it could blow out real easy....

 

 

Guy

 

 

Had that happen to me... the shop that did some head work and install for me damaged one of the dowels and decided it would be okay to install the head w/o it. Gasket lasted like 2 months. Bastards.

[80LS1T]

To me it looks like the head has non dowels it. Maybe they are there but I cant see them. This could be your problem right here...

 

 

Guy

[george.bryant]

those dowels are a pain in the *** when you're trying to get the head (which has the manifolds and turbo still attached) onto the block which is still in the engine bay of the vehicle...i rememeber stuffing 2 gaskets cause of those dowels

[80LS1T]

Those dowels may be a pain in the a$$ but they are important for lining the gasket up. I dont see how you could possibley line that gasket up with out them?

 

 

Guy

[Guest 73Turbo240z]

alright heres where i sit...

 

1. i feel i should point out, that the appearance of the internals is altered slightly from what your probally accustomed too.

 

2. it would appear i never had dowels... at least not with what i'd purchased, thus fueling my ignorance.

 

 

thats the block as photo'd by the guy i bought it from off here roughly a year ago. As i now see, no dowels.

 

 

that is the block as i had it before i slapped the head on, once again, no dowels, i didn't even think about there being some, if i recall right we centered up the gasket, then 2 of us slowly lowered the head to make sure we got it on w/ out disturbance, definately not the right way, i should have thought about the dowels, unfortunately i didn't know.

 

as you can also see, the pistons are a gold color, that is the ceramic coating, so it will mess with what your seeing in the head being off now.

keep in mind the car ran for a total of 48 hours, thats not engine run time, thats engine physically able to drive the car time, i'd say it actually ran as in firing off and consuming fuel, for less than 4 hours total before the felpro went buh-bye.

 

as it sit now, the HKS 2mm steel gasket has arrived, no installation instructions were included, but i was under the impression a clean deck and cyl head surface + a copper sprayed metal gasket + proper torque spec/sequence was the standard operating proceadure for a metal gasket, feel free to set me straight now, just in case i've got that wrong. in the mean time anyone have any ideas where i can locate dowels for this motor at? i'm going to check w/ a few guys in town, but i'm betting these won't be easy to find.

 

and for those more familiar w/ felpro, anyone know why they are blocking off block passages on there headgaskets? when the HKS does not?

[Guest 73Turbo240z]

anyone?

[BRAAP]

Head/deck locating dowels. Yes, you do need those head/deck dowels, this not only helps align the gasket properly i.e. fire rings to the chambers, water passages and the two oil feed passages, but they also help align the head to the block for those same reasons and for timing chain alignment, etc. If you can’t locate some yourself, I’m sure that there is someone here that can donate a pair.

 

Hmmm. All metal head gaskets… Those are a whole different animal. Depending on material compositions and design, can be very tough, also the softer gaskets, i.e. copper, are maintenance intensive requiring semi frequent retorqueing, etc, and some can also be very finicky to surface prep especially if they are of the thin stamped sheet metal variety.

To be honest, I typically don’t deal much with mega boosted turbo L-series engines and as such haven’t used or seen this HKS 2mm gasket. I’ve only dealt with the FelPro Lok-Wire gaskets on twin turbo Big Block chevy’s.

Sure would be nice if it came with some instructions though. I’m sure there are others on this forum that do have first hand experience with those HKS gaskets.

You might try starting a new thread in regards to “proper installation of the HKS 2 MM gasket”?

Sorry I couldn't be of more help...

 

Good luck and keep us posted on your progress,

[Cody 82 ZXT]

There shouldn't be any blocked off passages. All oil holes and coolant holes should have free passage into and out of the head as it was designed.

[80LS1T]

I would think a good machine shop should be able to get you some dowels. Someone just has to tell you were to put them in the block.

 

Guy

[george.bryant]

I have a book that covers all that. Ill have a look for it later.