Stainless bolt into cast iron - PeachParts Mercedes-Benz Forum

kerry · #1 03-27-2013, 04:48 PM

Turbo heat shield on my Fuso failed and I'm replacing it. It's held in place with 4 bolts. One into a boss on the turbo, one into the exhaust manifold and two into the turbo outlet manifold. They were all very tight and rusted, being original I think. Had to repeatedly use P B Blaster and then get the turbo and manifold good and hot before being able to loosen them. Is there an advantage to using stainless bolts in their place? I'm thinking stainless bolts are less likely to form a rust bond with the cast iron? Or is that not the case? I was planning to put never-seize on them but I don't know how much good that will do in such a hot environment.

greazzer · #2 03-27-2013, 05:03 PM

I would be careful with SS fastners. I thought it would be a good idea to use them on my bumpers, and other areas with a liklihood of some corrosion. Well, I realized that they easily cross thread and strip, and jump threads so you're stuck busting off the head. I went through a couple sets of SS bolts just on my rear Euro bumper only to really realize that they dont take a bunch of stress or torque. Maybe I just had junky SS fastners. I bought two bags from Fastnal thinking it would be a good idea to swap over everything. I currently have 2 bags left over less about a dozen fastners. Buying NOS metric fastner with real cadmium finish is a good option IMO.

t walgamuth · #3 03-27-2013, 05:09 PM

Quote:

Originally Posted by greazzer

I would be careful with SS fastners. I thought it would be a good idea to use them on my bumpers, and other areas with a liklihood of some corrosion. Well, I realized that they easily cross thread and strip, and jump threads so you're stuck busting off the head. I went through a couple sets of SS bolts just on my rear Euro bumper only to really realize that they dont take a bunch of stress or torque. Maybe I just had junky SS fastners. I bought two bags from Fastnal thinking it would be a good idea to swap over everything. I currently have 2 bags left over less about a dozen fastners. Buying NOS metric fastner with real cadmium finish is a good option IMO.

Is your euro bumper steel or alloy?

I would have thought ss would be fine in a hot environment.

greazzer · #4 03-27-2013, 05:15 PM

I am thinking it's steel. It was the SS nuts and bolts. I found them to be very problematic.

t walgamuth · #5 03-27-2013, 05:28 PM

Quote:

Originally Posted by greazzer

I am thinking it's steel. It was the SS nuts and bolts. I found them to be very problematic.

If it is steel it will be pretty flexible and thin. If its alloy it is like a us bumper but smaller in profile. I believe there are both kinds out there.

layback40 · #6 03-27-2013, 06:18 PM

Quote:

Originally Posted by kerry

Turbo heat shield on my Fuso failed and I'm replacing it. It's held in place with 4 bolts. One into a boss on the turbo, one into the exhaust manifold and two into the turbo outlet manifold. They were all very tight and rusted, being original I think. Had to repeatedly use P B Blaster and then get the turbo and manifold good and hot before being able to loosen them. Is there an advantage to using stainless bolts in their place? I'm thinking stainless bolts are less likely to form a rust bond with the cast iron? Or is that not the case? I was planning to put never-seize on them but I don't know how much good that will do in such a hot environment.

I have found that SS tends to bind up when used on exhaust manifolds/ turbos. Brass/copper nuts are good. Coppercoat is good as an anti seize in hot places. For holding heat shields in place low tensile bolts are best.

TheDon · #7 03-27-2013, 06:20 PM

I would put some coppercoat on them so they don't seize and go with a non stainless steel bolt.

TwitchKitty · #8 03-28-2013, 10:46 PM

In exhaust manifolds I used the bolts that were easiest to drill. I hope to never have to benefit from this strategy but if needed...

I bought the el cheapos from the building supply store.

If you can match the originals it would probably be best.

Simpler=Better · #9 03-29-2013, 10:08 AM

I would use brass threaded rod and any type of steel nut. The 617 manifold nuts are brass.

strelnik · #10 03-29-2013, 10:30 AM

Quote:

Originally Posted by Simpler=Better

I would use brass threaded rod and any type of steel nut. The 617 manifold nuts are brass.

For this reason Citroen has been using brass nuts on exhaust manifold studs since the 1930s. It is more common in Europe than here, I think Panhard used them on their sports cars too.

Stretch · #11 03-29-2013, 10:46 AM

X n to the power of n for copper ease type stuff

X 2 (is it?) for not using stainless (being a home DIY type of a chap have you ever tried drilling a hole in a stainless steel sink top? Way way way too hard for something like that next to cast iron; one white knuckle too far and you'll be asking about helicoils)

kerry · #12 03-29-2013, 10:58 AM

Copper anti-seize it will be.

weird beard · #13 03-29-2013, 11:46 AM

Mack trucks had a problem with turbo and exhaust manifold studs breaking due to stress. They were originaly regular steel studs but were upgraded to stainless. They still broke and siezed in place. The final solution was to return to regular steel studs, but they were longer and use spacers under the nuts. No more broken studs and if one did break it can be drilled out. When the stainless ones are broken, we generally call a machine shop to extract them and it takes them an hour or two.

The best thing to use is regular steel with nickle or copper anti sieze. Use studs and nuts if you can, gives you two points to thread apart if you ever needs to come off again. If you have enough room, put1/2 inch spacers under the nuts. Allows the forces from the metals expanding and contracting to be spread over more of the fastener.