Broken Stud

[Josparkz]

About 15 years ago I pulled my head bolts and put in ARP studs. I got retired, the truck did too. Rarely gets driven. About a month ago I start getting a progressively worse coolant leak. I thought it was the block heater. It seemed to be the block heater. I'm cleaning up the engine bay prior to heater install the other day, and lo and behold, I spot a hole where there used to be a stud. Okay, so that was the leak. Right behind number 2 injector. It's broke off about 1 1/4" down the hole. So the truck my check this month.
So, engine hasn't got hot ever or run hard for years. Why would a stud take and break like that?
Now comes the decision. Use studs again or go back to bolts?

 

[BigPapa]

No matter how good a company's reputation or how good their quality control is, things happen. Either you got the 1-in-a-million bad stud or it was over torqued. I'm a fan of factory head bolts until you get into very high HP builds. My '95 engine has over 550K miles on it and at one time was over 400HP and the head's never been off.

 

[Josparkz]

No matter how good a company's reputation or how good their quality control is, things happen. Either you got the 1-in-a-million bad stud or it was over torqued. I'm a fan of factory head bolts until you get into very high HP builds. My '95 engine has over 550K miles on it and at one time was over 400HP and the head's never been off.

That's a good track record. The studs were correctly installed and torqued. ARP says "hydrogen embrittlement". I think that bolt was in the water jacket, so yes, hydrogen, I guess.
Thank you.

 

[Darkbloodmon]

How often do head bolts break at stock levels compared to studs? A lot can change in 15 years of R&D into materials and metallurgy but I'm skeptical of hydrogen embrittlement a mechanical failure type that's been known about for 140 years (quick wiki search) to be the sole cause. I'm leaning on manufacturer QC unless you have some crazy electrolysis going on in your coolant system.

Not that I'm a chemist or material science engineer but common sense tells me if im making high performance hardware it should at least be designed to withstand/endure against the potential mechanical failures in the system its designed to operate in.

On a side note ARP is an old name that sells without much effort in the performance aftermarket, I opted for Xotic headstuds equivalent to 425s. My reasoning was its a newer company in a grandfathered market; it has to put everything on the table to prove its better than the brand you don't think about. I expect the R&D to be fresh and at lower price point representative of trickle down technology.

I just didn't see a reason why ARPs needed to cost so much, at the end of the day its hardware not rocket science. For example Fleece engineering made stainless manifold studs I could not justify 200.00 hardware. It's clamping a manifold, if it can't do this at the very least what more can it do to increase the cost? I opted for the stainless stud set from Pure Diesel Power for 60 bones, no issues and I've had my manifold off two or three times since for other unrelated work.