Does anyone know of a way to test a used Head stud to see if it's any good or not? Thinking aboutsome used ones just not sure if they will help or end up hurting??

 

I'm sure it relates to diesels also, maybe more because of the compression ratio's involved. Head bolts stretch over time from being torqued and from the pressure that is put on them, I would say especially in a diesel. I would say pass on used bolts and go with new ones or while your there...put studs in.

 

He's talking about studs.

Call ARP, and see if they have specs on lengths on their studs. Find out what their tolerance on manufacturing length is, then you can mic them and see what they are at. If they are within tolerance, go with them. But if their tolerance on the length of a stud is greater from factory than allowable stretch, its gonna be more of a guess if they are still good.

 

LOL...Durrrr

 

The only way they could be 'bad' is if they are stretched, which isn't ususally the case with studs. Studs are re-used all the time by racers.

Of course bolts suck, but Cummins has a simple plastic thread gauge that you match your bolts to to see if they're stretched. They include this plastic gauge with their headgasket sets. If you can find one, just use it to confirm your studs are fine.

 

The tool Cummins has is to measuer overall length is it not? Which wouldn't work since the studs are a different length.

 

I talked to one of the tech's from Arp and he said as far as they are concerned if the studs have stretched even one tiny bit there junk and throw them out! I'm not so sure about that though??

 

If they are stretched in an unloaded state, then they are past their yield point and don't have the tensile strength they did. But when you torque something, you do end up stretching it. If you are below its yield point, its called elastic deformation and will return to its orginal size/shape. Above the yeild point, its plastic deformation, and will not return to its original size/shape.

 

Dont do it man!!!!!!!!!!!!!!!!!!

 

I stretched a couple of supposed new head bolts about three years ago and lost a good Marine head gasket because of it. Had I known better, I would have replaced the bolt and torqued everything again to check them. As it happens, I found the loose bolts when I was tearing the truck down to replace the head gasket myself.

Ronnie