F*#$ing Headgasket!

[Guest 73Turbo240z]

ARAGRARAGGGGGGGGAAAAAAAAHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!!!

 

MOTHER F@$$*(%(

 

less than 48 hours of running, and the felpro headgasket appears to have taken a massive dump... and 8psi...

 

can't say more till i take it all apart (again :- ), but essentially on3go and i took it out tonight, had a few small mishaps with fuses, sorted that out, and were trying to figure out why the power was cutting up above 5500rpm...

 

did a 3rd through 5th load up on the motor, shifted 3rd and 4th at 5500rpm, just before it would cut up like usual, and upon getting into 5th, it felt like the power fell off, so i'm guessing thats when the gasket went, i didn't catch it till roughly a half mile to mile later when i noticed the plume of smoke trailing the car (night time).

 

It hadn't lost enough coolant to overheat or get even close, pulled over, checked it out, seep all along where the head meets the block, dandy...

 

So now i get to disassemble everything i just finished assembling... and pull the head to figure out wtf happened. I wanted to show my family this on christmas... i'll be hard pressed to accomplish that now.

 

In my plan of attack for ensuring this never occurs again, on3go has said he can hook me up with a HKS 1mm metal headgasket, he said it would inadvertently bump my compression a bit as well...

 

i'm sure combos like this are common, but the variable that throws me off is the AZ car pistons + L24 rods, he states that it alters the rod/stroke ratio, doesn't say if it alters the compression ratio, but then throwing in a HKS 1mm gasket that will bump me even further, i'm not able to take a educated guess at roughly what my new C:R would be...

 

what baffles me even more is, we've put thumpers felpro gasketed F54/P90a through TON'S more abuse, and it only gave out after repeated 20 somthing PSI highway pulls on his T3, i realize felpro's are far from the greatest, but it just seems odd to me mine would go so easily, and quickly.

 

more to follow following disassembly, just need to figure out the C:R question in the meantime.

[oinojo]

according to the Lengine software, with 240 rods youll be 11.8:1

odd, but with l28 rods youll be 8.89:1

 

well, your gasket probably went out because the engine hasnt been properly settled. Also did you retorque the head bolts after a good warm up? i always go over my torque specs after a couple good runs.

[Guest 73Turbo240z]

the one thing your software doesn't account for is the height of an AZ car custom piston, which unfortunately i don't have the specs on, i believe he moves the wrist pin height further up in the piston to comp for the longer rods IIRC... however if your calculations are remotely close, that HKS gasket may make tuning a real PITA, or doom my car to a AV or C15 only diet...

 

as for your second question, i put the head and block together months ago, followed ARP's directions for torque specs, i think i even went 5 over for each incriment.

 

however, you are correct, i did not re-torque the head stud kit after it's 1st full warmup about 48 hours ago. so its most likely that which is the culprit.

 

which lends me to wonder, did the gasket fail, or did fluids push over the top of it, and if thats the case, i wonder if i could flush both the oil and coolant, retorque the head, and possibly not have the gasket blown... i guess pending what others say about the possible new C:R's, i'll decide which to do, cause a flush and a retorque is a hell of alot easier than redoing the gasket, and if the C:R yielded by the HKS plus my unique cocktail of internals is forseen to be unmanageably high, then i really don't have anything to lose in trying to see if the gasket just lifted other then about $20-30 in fluids.

 

Someone feel free to set me straight if my logic is flawwed, i'm a little frazzled from the nights events, so my rationality may be slipping in leu of discouragement.

[spork]

If it leaked once...it'll leak again. You're going to want to pull the head off and go with a new gasket. I'd honestly suggest the stock nissan gasket if you don't want to go with a gasket like the HKS. Check all your surfaces to make sure they're perfectly flat. Run the car and retorque it after it sitting over night. Don't get on the throttle, just drive it like a old lady for a bit and try to stay out of boost. As far as your compression ratio ges...you've gotta figure out what you have now, and then we can help you figure out what it would be with a thinner gasket.

[wigenOut-S30]

I agree with spork. since it leaked once.. I would be willing to bet it created a grove in the gasket where it leaked. I would not use a felpro gasket at any point on a turbo engine. I run a OEM nissan gasket and have had zero problems. did you have a wideban hooked up when doing pulls? are you sure you didnt lean it out when getting into boost? Could have ran lean and just blew it.

[Guest strokerZ]

I am running an HKS metal headgasket after failures with both the OEM and Felpro gaskets. I have had no problems with regularely boosting to 20psi. You have to ensure that the mating surfaces are perfectly flat; if not, it will fail to seal regardless of what gasket you use...I feel your pain...hang tight..its just one more little bump on the road. Good luck!!

[JMortensen]

i realize felpro's are the greatest, but it just seems odd to me mine would go so easily, and quickly.

Do you STILL feel that way??? HKS, then Nissan, then Stone, then about 20 more cheap *** Chinese headgaskets down the list... FelPro. IMHO...

[Guest 73Turbo240z]

Do you STILL feel that way??? HKS, then Nissan, then Stone, then about 20 more cheap *** Chinese headgaskets down the list... FelPro. IMHO...

 

i was tired and mistyped, was mean't to read "i realize felpro's aren't the greatest"

 

anyway, looks like i'll start pulling the head after my last final for this semester, see if i can bang out a miracle to have the car still ready for my family by christmas.

 

i assume if i go OEM nissan that i'll need to go to courtesy's website? or is this fairly easy stock for any nissan dealership? what do they run on average?

[Guest 73Turbo240z]

after looking around courtesy nissans website i don't even see headgaskets...

[z-ya]

I beleive that with the Arizona Z pistons, the deck height is the same (or close to it) as Nissan flat tops with L28 rods. So at 87mm bore with a FelBlow, your CR should be around 8.7:1. FelBlow gaskets are no good for boosted applications. Either Nissan OEM, or HKS/NISMO/MSA metal. Or O-ring head/block with any gasket. Keep in mind that at 8.9:1, 8psi yeilds a lot more cylinder pressure than 8psi on a stock 7.4:1 turbo motor.

 

A freind of mine races a SCCA GT2 300ZX powerd by an 15:1 L28 all out race motor, and he only uses OEM Nissan head gaskets without problems. It's all about prepping the block and head properly.

 

What engine management are you using? If you are using stock electronics and injectors, you could have leaned out at 8psi on an 8.9:1 motor. Detonation can easily destroy head gaskets.

 

Nissan gaskets through Courtesy are around $70. They also sell the metal ones. Call them to get a price.

[Guest 73Turbo240z]

I beleive that with the Arizona Z pistons' date=' the deck height is the same (or close to it) as Nissan flat tops with L28 rods. So at 87mm bore with a FelBlow, your CR should be around 8.7:1. FelBlow gaskets are no good for boosted applications. Either Nissan OEM, or HKS/NISMO/MSA metal. Or O-ring head/block with any gasket. Keep in mind that at 8.9:1, 8psi yeilds a lot more cylinder pressure than 8psi on a stock 7.4:1 turbo motor.

 

A freind of mine races a SCCA GT2 300ZX powerd by an 15:1 L28 all out race motor, and he only uses OEM Nissan head gaskets without problems. It's all about prepping the block and head properly.

 

What engine management are you using? If you are using stock electronics and injectors, you could have leaned out at 8psi on an 8.9:1 motor. Detonation can easily destroy head gaskets.

 

Nissan gaskets through Courtesy are around $70. They also sell the metal ones. Call them to get a price.[/quote']

 

i'm running MSnS, the car was on a tune that was known good for 18psi, so we felt fine driving it around on 8psi, i wasn't trying for power/tune anything like that, we were just loading the motor up to help with break in and ring seating when the headgasket decided to go on hiatus.

 

so with an assumed 8.7:1 CR untill i get a hold of Dave, what will that do once i factor in a HKS 1mm headgasket? If it's unmanagebly high i'll go to a OEM nissan headgasket, if it's do-able i'd prefer to run the metal gasket for added durability, and if it bumps my compression to where i make more power with less PSI, so be it, cars already on a strictly 93octane diet, and if i have to start making trips to the local airfield or making homebrew, then i'll do what i have too.

[z-ya]

Did you verify the timing with a timing light? I would not trust it from one installation to another.

 

Start making homebrew either way 8^). I just sampled the my first batch of the winter last night!

[Guest 73Turbo240z]

Did you verify the timing with a timing light? I would not trust it from one installation to another.

 

Start making homebrew either way 8^). I just sampled the my first batch of the winter last night!

 

whole motor was build from the ground up according to FSM specs, or aftermarket specs where applicable.. we started it for the 1st time 48 hours prior to it popping.

 

The timing was checked, i'd have to double check w/ thumper since he had helped w/ that, but i believe in setting up MSnS we had to get it to around 50 degrees BTDC to setup MSnS to accurately trigger.

[Thumper]

but i believe in setting up MSnS we had to get it to around 50 degrees BTDC to setup MSnS to accurately trigger.

 

Sorry to hear the headgasket blew. But the timing is not set at 50 degrees. That is what the trigger angle is set at. Your timing is 24 at idle then 39 degrees at full throttle. At 7psi I am unsure what timing is at but my guess is 33 degrees.

 

When you go from a oem gasket to either a felpro or hks gasket you compression ratio is bumped up roughly .1-.2 So if you go from a felpro to a hks there is no difference. But if you go from a felpro to an oem then the compression ratio will go down .1-.2 If you are really at 8.7:1 you might want to do this or even go to a 2mm hks gasket. 8.3 would be alot better than 8.7 in my opinion but first see what compression ratio you have. My felpro gasket knock on wood has handled 20psi with no problem with stock head bolts so we better check everything else twice. Also your high rpm miss could be that we didn't have the trigger angle set big enough so your higher rpm timing didn't have enough time to get the signal and send it to the coil. Its a simple fix that we can do if thats the problem. How long after the fuse problem did this happen? If you were going lean then this might have caused your premature failure.

[Guest 73Turbo240z]

Sorry to hear the headgasket blew. But the timing is not set at 50 degrees. That is what the trigger angle is set at. Your timing is 24 at idle then 39 degrees at full throttle. At 7psi I am unsure what timing is at but my guess is 33 degrees.

 

When you go from a oem gasket to either a felpro or hks gasket you compression ratio is bumped up roughly .1-.2 So if you go from a felpro to a hks there is no difference. But if you go from a felpro to an oem then the compression ratio will go down .1-.2 If you are really at 8.7:1 you might want to do this or even go to a 2mm hks gasket. 8.3 would be alot better than 8.7 in my opinion but first see what compression ratio you have. My felpro gasket knock on wood has handled 20psi with no problem with stock head bolts so we better check everything else twice. Also your high rpm miss could be that we didn't have the trigger angle set big enough so your higher rpm timing didn't have enough time to get the signal and send it to the coil. Its a simple fix that we can do if thats the problem. How long after the fuse problem did this happen? If you were going lean then this might have caused your premature failure.

 

This happened were guessing right after we left from the fuse issue, fuse happened at 249/louetta, did the 3rd, 4th, 5th pull northbound and u-turned at the CVS like usual, noticed a little spray on the windshield, figured it was from a puddle or somthing given the day, headed southbound, i think i might have gone into boost 3rd and 4th, mike was watching the laptop the whole time giving me tach readouts for the pre-5500 rpm shift, let off, glanced back and saw the huge trailing plume, and then pulled over at the target at louetta/249, which is when we found the seep.

 

car never peaked above 200 degrees, not even close, highest temp i got gimping it home was 186, so i suppose i have that to be thankful for.

 

i'll probally start disassembling it tommorow since i have my final tonight. with that headstud kit though, i don't think i'll be able to just lift it enough to swap the gaskets, i think i may have to totally take the head up and out... which will mean disconnecting all sensor wiring, vacuum hoses, downpipe, oil drain, intercooler plumbing, etc...

 

it'll basically be like going back 2 months and starting again. not fun.

[z-ya]

You need to verify that the timing that is programmed in the MS is the same as measured with a timing light. Set the timing to 5 degBTC in the MS at idle, and then measure it with a timing light using the timing tab. This will confirm that advance you set in MS is accurate.

[ngrimm]

That's too bad on the head gasket. In the Turboford world we use a more expensive than standard Felpro gasket and have great results. I blew a standard one very quickly but I have used the better (1035) gasket for over two years including many trips to the strip. I have been running over 25 psi on my hy-35 and the gasket even survived an overboost of over 35 psi when the actuator hose came off. Would it be possible to remove the studs so you could just slip the gasket in? Good luck getting it going again, just remember it's just another bump in the road. Norm

[BRAAP]

Have any of you Turbo guys tried using the ARP Head stud kits on your boosted L-series engines? The ARP stud kits will clamp the head down tighter thereby “squishing” the head gasket the much tighter and as such should hold up a little better under the boosted abuse that seems to bellowing your gaskets now. This isn’t “cure all” or a “fix all”, but it might be just enough to allow the gasket to live a longer life than with the OE head bolts you guys are currently using.

The only down side I have issues with regards to the ARP head studs is during any time you have to remove the head and one or more of the studs won’t thread out of the block, then removing the head can be “very” tedious.

[Guest 73Turbo240z]

i'm using ARP head stud hardware. so i'll find out soon enough i suppose.

[johnc]

There are two advantages to a stud over a bolt:

 

1. The stud threads themselves are finger tight in the female threads with the nut threaded over the stud. Less turning force is required to overcome thread friction (because fewer numbers of threads are being turned on) so its easier to achieve the desired level of residual stress in the fastener combination.

 

2. Residual stress in the fastener combination is more evenly distributed throughout so the fastener is more efficiently installed.

 

A torque number on a torque wrench measures resistance to turning. The fastener industry generally agrees that about 50% of the torque number come from the friction between the nut/bolt head and the mating surface, 40% from thread friction, and 10% from actual stress induced in the bolt/stud.

 

From the above its easy to deduce that most important factor affecting proper fastening is thread condition. Undamaged, clean, and properly lubricated threads are far more important then the choice of a proper strenght bolt vs. a proper strength stud.

 

ARP has developed a special moly based thread lubricant to specifically address this issue and to ensure consistency in torque readings.