Busted Knuckle

A friend of mine (State Trooper) has a 98 Vert and wanted to do some mods without changing the resale appearance of the car. He was @ my house and I was removing a brand new freshly chromed 170 degree thermostat (going to use polished unit instead) and since I have about 5 different temperature stats I just gave him the one I was removing. I also gave him two stainless steel cap screws to install the unit with a warning about using anti-sieze on stainless to aluminum. Offered to give him some GM Dry Film Anti Seize Part # 12377953 and he said not to worry, he had some. I gave him the torque values (10 nm or 89 in lb) and told him not exceed the values. He called this morning and said "I have a problem"!! I will not bore you with the rest of this story.

$$$frumnuttin'

But you do need to bore us with the problem. I need to know if he overtorqued the joint, the failure mode, etc. Generally, stainless steel has a high friction coefficient going into non-ferrous metals...could rip out the threads if torqued too high...that would be a huge problem in a casting or forging of aluminum. If he did not exceed the recommended torques for NON-stainless fasteners...e.g. standard steel fasteners, then he could not have reached enough tension (given the high friction) to do any damage...the torque wrench would simply click like a ratchet. Follow me??

LoneStarFRC

Another thought came to mind here. Did he "hydro-lock" the bolt hole? In other words was there excessive anti-seize (or other foreign material) in the hole when he inserted the bolt? Since it's a blind hole, that will cause damage too.

mph1972

Sounds like things went south fast for him. These stories are the ones that really get me worried about adding things to my car.

Busted Knuckle

Update: The rest of the story. The stainless cap screws were installed with no anti-seize. The owner was polishing some new SS "can't cut" hose clamps and the son (14) thought he would help his Dad out and installed the new thermo without benefit of a torque wrench. The old suspension torque philosophy "Tighten it as tight as you can and then another half turn" !! The father came back to the garage and
$h%# his pants. He knew they were way over torque so he did the natural thing and tried to back them out. The threads were "gauled".
Problem has been solved but not without a lot of work. Drilling and retapping in the confines of the thermo area is not how you want to spend a Saturday and half way into Sunday.

IM QUIKR

....and the son?? can he sit yet?

$$$frumnuttin'

Yup, that is what I was talking about above...glad someone knew how to repair it

Glennm27

NSTG8R

good umm learning experience?

Cobra4B

Well being someone that learns most everything "the hard way" I can tell you the son will probably never overtorque another fastener in his life... he's in for a long life of proper torque settings

Mike Mercury