The Correct Way to Install a Head Gasket?
#16
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At the shop we tend to try not to use teh standard arp's more than once even though we know some here do w/o issues.
That's why i went w/ the L19's.
W/ arp's we hand tighten the studs and then torque in increments up to the required spec the reg ones being 80-85 and w/ the L19 i don't remember exactly but it was more like 90 but i may be wrong it's been a while since i've installed them.
We never torque then un-torque on any of the evo/dsm motors we work on but i'm not the head machanic just a wrench turner that likes to learn new things!
Also i AM NOT a fan of using copper spray on the HG
#17
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I would never torque a gasket to any thing then back it off then retorque. You have already left a "foot print" in the gasket and have compressed it to some extent. Would you be ok? Probably. If it were my car I would by another $80 gasket and have the peice of mind even tho you will more then likely be ok.
#19
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I would never torque a gasket to any thing then back it off then retorque. You have already left a "foot print" in the gasket and have compressed it to some extent. Would you be ok? Probably. If it were my car I would by another $80 gasket and have the peice of mind even tho you will more then likely be ok.
BTW I think if you truly wanted to reuse the ARP studs and you were the one who installed them originally, it would be okay. The reason we torque is to stretch the bolt to proper fastening strength. Over-torquing is what puts stress on the bolt and threads. If you were running high boost on the studs before I would find a dimension to measure the length of the bolt to determine if it is still serviceable. That is the only sure way to tell.
Just for my background I too am an Aviation Mechanic with over 12 years experience. I have also been trained on proper torque methods by Boeing (on top of all the college classes) and was certified to torque and seal bolts on the Apache.
Last edited by althemean; Nov 4, 2008 at 06:23 PM.
#20
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Bump from the past headgasket bicholas....
My head gasket leaks oil. It's been seeping oil all summer. So the step I was nervous about was in fact crap. DO NOT Loosen the studs with a new gasket in place.
I just got a new OEM gasket and L19 studs. Should be fixing it in a couple weeks. I plan on putting one cycle ( 60 lbs) on the new L19 studs with the old gasket. Then installing the new gasket and ramping up.
Any more input on copper gasket spray..... good or bad.
My head gasket leaks oil. It's been seeping oil all summer. So the step I was nervous about was in fact crap. DO NOT Loosen the studs with a new gasket in place.
I just got a new OEM gasket and L19 studs. Should be fixing it in a couple weeks. I plan on putting one cycle ( 60 lbs) on the new L19 studs with the old gasket. Then installing the new gasket and ramping up.
Any more input on copper gasket spray..... good or bad.
#21
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I have always known on these engines to use copper spray on MLS gaskets, especialy if the head and block have not been decked. I am interested in hearing some reaons to do otherwise by some of the more experianced engine builders.
#22
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Replied to other thread, but no spray, install head, torque to 30, then 60, then 80, then 90 (or whatever your final value is--I did 93 I think). Do NOT go back down to zero! I think you figured that out though IF it makes you feel better, I've done two HG jobs on my car in the past year as well. Live and learn.
#23
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I've done several HG's with and without the copper spray.
I torque in steps. 20-30-40-50-etc. helps seat the head evenly and clamp down on the gasket without pinching a corner or anything weird.
I hand thread the studs into the block. To the guy who said that you need to pre-stretch the fasteners... that's plastic deformation. If the fastener has a load applied to it and it doesn't come back to its original length... you've gone past the yield point of the fastener into the plastic deformation region and it's permanently deformed. You want to torque to yield, which is most accurately done by a bolt stretch gauge (dial indicator) This is basic material science.
I torque in steps. 20-30-40-50-etc. helps seat the head evenly and clamp down on the gasket without pinching a corner or anything weird.
I hand thread the studs into the block. To the guy who said that you need to pre-stretch the fasteners... that's plastic deformation. If the fastener has a load applied to it and it doesn't come back to its original length... you've gone past the yield point of the fastener into the plastic deformation region and it's permanently deformed. You want to torque to yield, which is most accurately done by a bolt stretch gauge (dial indicator) This is basic material science.
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