****!

was it:

A: AEBS Sleeves having an issue?

B: ARP Head Studs needed to be retorqued causing head lift?

C: Didnt use recommended spray on headgasket?

D: Lack of CAS wire upgrade allowed an isolated event of knock?

E: Poor Tuning allowed detonation?

F: Poor surface preperation?


Heres my take on each...

A: Not likely, the symptoms are too light. Others have had AEBS sleeves drop... but I am not getting poor sleeve job symptoms. My symptoms do not include coolant in the crankcase or overheating. I simply get excess coolant pressure under long full throttle boost runs. In result coolant blasts into the overflow, out the overflow vent, out the vents in my hood, and all over my windshield!

B: ARP Headstuds many say are to be retorqued at 1000 miles. Well I am at 1400. Technically it IS possible to retorque on the 350z, but its not anything anyone is going to do. We are talking about several days of labor to do this. One member that had the chance to check his ARP headstud torque after putting miles on the motor said that they were a few ft-lb loosened, but nothing serious. I had my headstuds torqued to 73 ft-lb.

C: AEBS recommends a spray on the headgaskets. I was never told this until after I put my engine together. I cant recall what spray they recommend, but its not the typical copper spray that many tuners use, including myself in some applications.

D: This is possible. Since the car has been running, I have made about 50 passes on my dyno. Never was I given any evidence of knock. But it would only take a single isolated occurance. For safety measures next time I will use one.

E: Not likely. My tuning has been observed as conservative by myself and other tuners I communicate with while tuning high HP engines. I have seen handfuls of cars have issues with detonation and knock on my dyno, and my car was showing no signs while being observed on the dyno.

F: The heads were brand new from Nissan. The block surface was from AEBS. There was a step height varience from sleeve to sleeve... also a varience around the circumference of some of the sleeves. I could just barely catch my fingernail on high and low spots. When I addressed this issue with a machinist and he looked at it he felt that it was not substantial enough to be of concern. I took his advice and left it be.

Notes: I do not have the time to repair this right now. I will soon. This time around I will use a copper headgasket spray, and I will be decking all surfaces fresh. Things currently up in the air are the decision on if I will use this AEBS sleeved block or not, and if I will use ARP head studs again or not. Last year we had a 585rwhp 300ZX that couldnt keep its headgaskets together and after going back to stock never had another problem. If when I tear down my engine the ARP studs are not at the full 73 ft lb I put them at, I will probably go back to stock bolts.

I feel that at the moment the most likely cause of the problem is head lift. I say this because the car has no issues with regular driving and light boosting. Only under long full throttle runs does it fault. This engine has held well over 100 full throttle runs thru multiple gears at 522rwhp tune. It lasted about 10 passes on the dyno at 575ish. The first sign was after about 15 full throttle street passes up to the top of 5th on the street. Thats when I first saw a sign, which was obvious... light mist on the windshield. While driving I stuck my hand out the window and rubbed my finger in it and tasted it and that bitter coolant flavor told me right away that I blew a headgasket.

these things happen when pushing an engine hard. its not something i cared to keep a secret. Its just something that straight sucks and is gonna take me a shitload of hours to fix.

awww ****.

-charles

 

sorry to hear that. hope all works out for you when you go back to repair it. good luck.

 

it will definatly work out. the only thing here that requires hope is that it doesnt happen again!!!

 

very true!

 

Hey Charles.....sorry to hear about the problem. I know working alot on Honda's and having sh*t like this happen after getting it all together really sucks a**. It's too bad the VQ wasn't a lot easier to pull and take apart like a Honda. I guess when we get to these power levels everything has to be just right to last. I feel for you man...I really do. Just plain bad luck.

 

I was wondering when I would see your next post about how you crossed 600rwhp. This is not the post I wanted to see.....that sucks dude! I hope it does not happen again.

 

no worries, I will blast thru 600whp within the next couple weeks. i am still on target to have my 10 second passes ASAP. I am just looking at a real rough weekend pretty soon!

 

Crap, sorry to hear.

Did you get your sleeves o-ringed? Is o-ringing recommended by AEBS for this application? Your thoughts on the subject?

 

Sorry to hear about your troubles charles.

Is this the first blown headgasket on anyones car without other major damage?

 

My sleeves were not o-ringed. I havent looked at the stock headgaskets in detail but supposedly this is not compatable with the stock headgaskets. next time i will take a look at that. i believe that AEBS only o-rings the block when you are going to use the cometic head gaskets. I might call cometic and see what they think of my ordeal.

This is the first blown headgasket report that I know of. I definatly do not have other damage the car is running great and making tons of power... it just fills up my overflow bottle within a couple full throttle passes. If routed my overflow to the ground I wouldnt even know it until I ran low enough on coolant to loose interior heat and the engine started to overheat.

 

Hey Charles, when you blew your headgasket, did you have whitish/grey smoke out of your exhaust? Cause for right now, I have smoke coming out of my exhaust and wanted it to know if it could be a blown headgasket as well. I havent gotten it checked yet since I am doing my build up right now. Thanks!

--Tim

 

After beating the poop out of the stock block...now you have problems....sorry to hear...get her fixed and go get that 600whp

 

After running the car for 20 min see if it goes away. This smoke is normal during cold starts and can linger for up to 15 min or so depending on how quickly you heat everything up and evaporate any condensation.

as for my car, no it does not smoke anything. its actually great if you watch the exhaust during a full throttle run, other then the sound you wouldnt know its not at idle... not a single visable anything comes out of the tailpipe.

What is happening is under extremely high cylinder pressures my engine is letting compression pressure seap into the cooling system causing over-pressurization and this opens the radiator cap with force and the coolant blasts into the overflow tank.

 

ahhh the fun of fully built projects. Stuff like this is very common, you just dont hear about it. Most tuners fix it quickly and quietly out of fear of lost respect. I really just dont care, **** happens and ill fix it quickly when I have the time.

 

I think your culprit is the block. I would never install a block with an uneven deck. Not sure why your machine shop did not level all the sleeves, but only the highest one will have the correct clamping load.

I would go with the Cometic gaskets and a clean milling of all surfaces and it should run strong as ever.

 

Bad luck Charles and sorry to hear of this mini diasater, not to worry you know the old saying ''no pain no gain'' and I'm sure you will solve this issue when you get time to investiagte thoroughly, good luck.

Peter

 

Sorry to hear about the minor set back. My headgasket went a month ago and I went cometic. Love what your doing thou.

 

sorry to hear about this charles!!! the good news is- you know how to fix it/ and can...yourself!

good luck

 

Charles..

I was looking at your other post about the Polished fuel rails, and sort of jumped between posts..

I wrote:

Charles, Just a great look for a "Show Car" with optimum function !
Looks like a Jewell ! - (sp?)
Now to add the FI one piece Plenum so those fuel rail's can be seen.

Cheers Amy -
P.S. Thanks for being "Open" about the head lift issue.
Question: If the ARP studs do lose tension at X number of hours, how would we check what the existing ( found ) torque really was?
Should we set the Torque Wench to say 55 and check then
increment the torque wrench by 5 lb's until the nut on the stud turns?

Your method please..

Thank You...

 

You are right many shops wouldn't reveal this but that diefferetiates you from a business only shop to a business/enthusiast shop which I find are better to deal with.

Look forward to hearing your results as many of us follow your progress.