Broken Valves

[More Power]

Member Bill Poser, owner of a repair shop here in Montana, sent these images to me showing a couple of different 6.5 valves that were missing pieces.

Bill said: "These are the pictures of valve breakage I spoke to you about. If you notice that these appear to be two-piece structures. This is the second 6.5L engine that we have had this happen."

In a later email message I asked Bill if this was an original GM engine or if the heads were aftermarket. Again, Bill said: "The heads were original equipment from the GM factory and never been touched."

I don't remember hearing from anyone else who reported a similar problem, which is why I asked about whether the heads were OEM or aftermarket.

Poor heat treating could be a possible cause, but does anyone have an explanation?

Thanks,

Jim

[Dvldog8793]

improper heat treat or stress zone, creating a heat effected zone that essentially forms the "two pieces" that your friend talked about. if you look in the one picture you can see the different metal grain that would indicate a stress or heat zone. I would bet a bad batch of valves either due to poor heat treat or base metal issues.

[Robyn]

I agree 100%

These valves are most likely a forged piece and the face is induction hardened after they are forged, then finish ground.

If it's a metalurgy issue, a heat treat spec issue (as in too hard) the part line where the hard face blends into the more "tough" center portion resulted in an area that was prone to cracking.

I am not sure what material they used on these.

Heavy engines often use Stellite, stainless steel, and some real high perf stuff use titanium

My guess on these engine would be a more common austenitic steel ??????

Bottom line, this failure is very likely a heat treat screw up, as in the face area was "Too hard"

I have never seen a valve fail this way.