Ian Carr

a Blown Head gasket

Be aware when using aftermarket head studs (EXP: ARP) MAKE SURE YOU USE THE AFTERMARKET TORQUE SPECS AND NOT STOCK TORQUING SPECS!!!

We used arp head studs on our rebuilt motor and after 800 miles of break in and only 9 days of driving the head gasket went. 5 of the 10 nuts holding the head on where FINGER yes i repeat FINGER loose and 9 of the 10 where loose. The result of this are as fallows:




so this time around i will make sure i use ARP torque specs not the stupid stock "turn the nut 90* then wait 30 minutes and come back and turn another 90*"

-Ian

Ian Carr

OK NVM i guess i do not have ARP head studs but the previous owner might have over tightend them and stretched them so NOW we are getting ARP and or stock head studs

-Ian

dand86951

You should carefully check your deck height of each liner referenced to the block and to each other before you put it back together. You possibly had a liner sink on you, and it may not have had anything to do with the torque method.

Perry 951

Did you retorque the head after initial run in?

ehall

a 90.00 dollar gas bill?

mark944turbo

"so this time around i will make sure i use ARP torque specs not the stupid stock "turn the nut 90* then wait 30 minutes and come back and turn another 90*"

Torqueing by angle is a superior method.

On another note, do you trust the person who torqued this head? Did they use an angle meter? The studs would be more likely to break than loosen if they were overtorqued. Sounds like somebody undertorqued to me.

Ian Carr

We did not use a angle meter but we must have been very close to 90* each time. If being off 5* will cause the head gasket to blow then it is definitely not "Superior" You should always have a torque spec on a stud not "turn 90* then turn 90* again"

Ill let you guys know tomorrow if i really do have aftermarket studs or not. If they are original its probable that after the 200k miles on this motor they stretched and wore out. Hello new head studs and yes i will "use a angle meter" this time around

FAST44

What are the APR specs?

Sam Lin

Spoken like someone with zero understanding of material properties. Do a search, it's been explained before, torque by angle is a far superior method.

Sam

Oddjob

The factory workshop manual, turbo supplement, shows the cylinder head torque specs to be 14 ft lbs (1st step), 36 ft lbs (2nd step), and 65 ft lbs (3rd step). I have only used this procedure, not the 90 deg method, and have never had a problem.

hosrom_951

Do you know that the APR studs need to be re-torqued after 1 heat cycle?

At least that is what the APR users say, after doing a search on it.

David Floyd

I don't heat cycle my ARP studs, I was told to let set overnight after torquing then do a final torque same as the last step the night before...

mark944turbo

"We did not use a angle meter but we must have been very close to 90* each time. If being off 5* will cause the head gasket to blow then it is definitely not "Superior" You should always have a torque spec on a stud not "turn 90* then turn 90* again"

Ill let you guys know tomorrow if i really do have aftermarket studs or not. If they are original its probable that after the 200k miles on this motor they stretched and wore out. Hello new head studs and yes i will "use a angle meter" this time around"

I am sorry to say that everything you have said is wrong. You should stop guessing, this is not the first post that this has happened in.

Some facts:

1.Using torque angles is more accurate because of the effect of friction on the torque wrench force. 50% or more variation is had just by switching the weight of the oil on the threads. This is ignoring the effect of a small imperfection in the threads. Torque angles allow us to reach a consistent preload in the fastener.

2. The studs do not stretch and wear out with time. They either corrode and fail by breaking, or they have a fatigue failure due to bad preload. The number one cause of failed fasteners is undertorqueing. If the head studs are torqued correctly they will not stretch past their elastic deformation range and they will not wear except due to corrosion.

Were you there when "we" torqued the head? How can you not know what brand of head studs you have when building a motor?

Sorry I sound angry, but I am disappointed with some of the misinformation that has been posted lately.

Tom M'Guinn

TurboX -- sorry to hear of your problems. I am in just about the same boat. I have about 300 miles on my HG, and it is starting to puke up coolant when on high boost. I have to believe that my deck is not flat or a cylinder has sunk or is shifting. I used Raceware and WFHG and followed the torque procedures and re-torqued as specified by Raceware. Head was machined recently, deck scotch-brited to remove all gunk. Tom C says my pistons will be ready next week... Bring on the 3L...

944CS

i think the problem is the studs in these particular engines, i know of another turbo motor built by a very reputable tuner whom i will not name which had one of its arp studs loosen