Question for Cummins/diesel mechanics

[catfishblues]

I've got a set of pistons a guy picked up at auction because they were slightly damaged. Mostly a ding around the piston skirt or something minor like that. I'll upload pics from my phone shortly. The question is, is there any reason that one wouldn't apply a little gentle filing/polishing to the nicks to smooth them out and eliminate stress risers so he can sell them cheap? They're brand new pistons that were (I guess) rejected because of the damage. I don't know enough about the design and stresses these things see to make a judgement call.

 

[catfishblues]

There are two with marks like the one in the first pic. I don't know what it represents, because there is no visible damage. I don't know if a fissure or something was noticed when passing through QC, but my naked eye can't see anything. The one with damage at the top edge of the piston is extremely minor and looks like it could be smoothed with a hone to avoid any potential hot spots. Again, I'd like an expert opinion before I tell this guy we'll do anything.

 

[broncosbybart]

I bought new pistons for mine during the rebuild on my 4BT. Shipped my good used pistons to get the tops and skirts coated. The tops got damaged in transit, like these. I was told to not chance it by several folks. Pistons aren't terribly expensive, so why chance it?

 

[Fabrik8]

I wouldn't risk it. The one on the upper crown edge can likely be removed, but most of the other ones are in spots that could be highly stressed, like around the wrist pin bore.

Put it this way: saving a little money on some blemished pistons is not worth potentially destroying an engine if you have a piston grenade on you. All of a sudden the relative piston cost becomes really cheap...

 

[mysterync]

Agree with the above! No reason to chance it. Just buy a new set.