Overheard a kid at the parts counter say "torque to yield is a scam"

I was waiting for a thermostat gasket at the NAPA on Broadway last Thursday. Some young guy, maybe 19 or 20, was telling the counter guy that torque to yield bolts are a scam invented to sell more bolts. I almost choked on my coffee. That stuff is basic engineering, head bolts stretch for a reason. I remember my first time doing a head gasket on a 5.4 Triton about 12 years ago. I reused the TTY bolts like an idiot and had a coolant leak within 500 miles. Had to tear it all apart again, cost me a whole weekend and 60 bucks in new gaskets. That kid will learn the hard way just like I did. Has anyone else had a new guy argue about something basic like that?

3 comments

3 Comments

hannahm3919d ago

That 5.4 Triton story hurts to read because I did the exact same thing with a 4.6 in my old F-150. The ARP stud kit was 300 bucks and I thought I was being smart saving 12 bucks on new Ford bolts. Leaked at the back corner of the passenger side head within 200 miles, had to pull the intake and everything again. On the TTY thing, your point about head bolts is spot on but I gotta push back a little on the "stretch for a reason" part. TTY bolts actually work by permanently deforming into the yield zone of the metal, not just stretching like a spring. The bolt actually changes shape permanently to clamp the head tight, and that's why reusing them loses the clamping force completely. Did you ever mess with the old GM LS engines that use regular torque to angle bolts that are technically reusable?

sam_thomas19d ago

Honestly that LS torque to angle thing is interesting because most people don't realize those bolts are actually working like a controlled crush washer between the threads and the head surface, not just stretching.

dakota_patel9819d ago

Wait, @sam_thomas, are you saying I've been calling my spark plugs "torque to yield" this whole time?