ARP thread corrosion

[wil892]

I bought some ARP studs on ebay a couple of years ago (cosworth type). They had been used briefly in a high performance engine. Anyway when I got them they were in great condition, but no washers.

After a couple of years of sitting in the same box a few of them have rust corrosion in the threads. Nothing major, and is removed with a wire brush.
However i'm concerned there may be small pits from the rust which may affect the studs. Has anyone come across this before? I'm not sure whether to use them or bite the bullet and buy these new VW specific ARP diesel bolts.

I can get replacement washers from the ARP supplier in this country but they did say worst case scenario that a stud would snap or deform causing distortion of the block and a piston would seize, as a result of this surface corrosion.

[sdwarf36]

Run 'em. The rust is on the outside-it didn't affect the metalurgy of them.

[Toby]

I bought some ARP studs on ebay a couple of years ago (cosworth type). T
Nothing major, and is removed with a wire brush.
However i'm concerned there may be small pits from the rust which may affect the studs. Has anyone come across this before? I'm not sure whether to use them or bite the bullet and buy these new VW specific ARP diesel bolts.

I can get replacement washers from the ARP supplier in this country but they did say worst case scenario that a stud would snap or deform causing distortion of the block and a piston would seize, as a result of this surface corrosion.

You must have way too much time on your hands. The ARP studs are overkill in the first place and a tiny bit of rust won't effect anything. Likely, a large amount of rust (once cleaned up) would not hurt anything either. You aren't assembling space shuttle motors; just old VW diesels.

[theman53]

8740 chromoly is what the studs are made of. They shouldn't rust. It is the same as running a carbon steel wire wheel on a stainless steel part. I would assume that part of the block probably transferred a bit onto the studs and that is what you are seeing. It shouldn't hurt a thing.

[Toby]

I do not think you are right about that. The come with a black oxide finish, which is a type of rust. 8740 is about .4% chromium, whereas stainless steels are typically 10% and above.

[theman53]

But it is a high carbon which don't oxidize as easily as lower carbon. 40 percent carbon. It will rust but nothing like a grade 2 bolt. What I am saying is it isn't that big of a deal and pretty much just on the surface.

[8v-of-fury]

Lucas knows what he's talking about when it comes to fastening hardware, I'd take his word on this one.

[wil892]

Cheers for the replies! I will run them with an AAZ gasket then, I'm hoping not to get any leaks. Toby it was actually just a concern over building an expensive motor and then running some studs I was not sure about, no harm done though, its saved me an expense!