I removed my stock downipe, and all of the studs came out (at least I didn't break any). I noticed the threads on some of the studs were pretty dull or flatened. .
I have brand new studs and nuts to install.

Before I do, should I chase the threads with a tap? I tried to brush them out and hit them with brakleen
If I should tap, can anyone confirm it's a regular M10 x 1.5 thread?

Any other advice from those who've done it before? Planning to use high temp anti-seize.

 

I used these for mine: https://www.mcmaster.com/93275A040/

M10 X 1.5 confirmed.

 

Thank you. Not sure I'll be able to get a tap between the frame rail and the turbo outlet, come to think of it.

 

I didn't tap mine or anything. Held up just fine when I replaced them last. I also used High-Temp Anti-Seize for the install.

 

I tapped mine with m10x1.5, then set the studs and nuts with milk of magnesia. The tapping pulled out a lot of crap. so I recommend it.

 

Interesting. Never knew MoM could be used as anti-seize. Just did some searching, and turns out it is a really good one (for non conductive parts, i.e. not spark plugs).

Thanks, cheers.

 

Yup, fantastic for super high heat.

Side note, many after market DPs will require you put the studs in with the DP in place. It's a pain, but the only way they'll fit.

 

Good note. Or some people use high grade bolts. For now, I'm just swapping my USDM pre-cat for a JDM OEM downpipe. The easiest option, and it's still a pain in the butt. Makes me want to replace the whole engine.

 

Re-threading kits are a thing. Gentler on existing threads and many are designed to be used with wrenches or sockets. Lang 971, for example.

 

you can also add a washer to your old stuff and re use it. new is better obviously, but its more a matter of what is easier to get in the space available

 

Few notes on this -

- Remove the ABS heat shield, secondary turbo inlet pipe, and Y-pipe. Makes a GIANT difference in room to get to everything.
- Get a pack of these: https://www.clipsandfasteners.com/M1...-p/pm33629.htm - they are VERY gentle on the studs and are copper coated to prevent seizing up if you do have to remove it down the road. They aren't as aggressive as Mazda's nuts. 9 times out of 10 they will come cleanly off the stud, and if not, you can many times remove them from the stud and re-use the stud.
- Use a thread chaser to clean up the threads in the turbo. You can use a tap but it's designed to cut new threads, a chaser is designed to clean up existing threads and get trash out of there. A tap can work but some times it can cut into the threads and try and make new threads.

Dale

 

the Mercedes part number for the nut is 000-990-31-50, obviously the clips and fasteners price is fine ($0.77 each), but you can do way better ($0.26 each)

 

Thanks folks, might order those thread chasers and copper nuts. Will report back on progress.

 

Just to close the loop.

The Lang thread chaser worked on 3/4 bores. I did have to resort to a tap on 1/4 bores. I actually bent the thread chaser on the one bore that needed a tap. I tried mightily to get the chaser to work, even before I bent it. I guess a thread was really galled, but the tap made short work of it. For anyone doing the same, I would recommend to have both on hand and to try the thread chaser first.

All studs are replaced with anti seize and holding torque, as the downpipe is replaced.

 

nickel grade anti-seize is rated for over 2000°F, every rotorhead garage should have some on hand
.

 

I actually used 1600*F regular silver stuff, but I'll get a hold of some of the ultra high temp stuff to have it on stand by.

I think (hope) I'll be OK. Most of the information I checked mentioned post-turbo EGTs shouldn't get too much higher than 1600, especially in my run-of-the-mill stock turbo build. I'd think the turbo manifold would be lower than peak EGT temp.

Honestly if I take it apart again, it would probably (hopefully) be an engine replacement. I'm mostly trying to get the car and peripheral systems ready for a nice new engine.

 

I use it on every bolt on the chassis, if you keep the car long term it pays off by everything coming apart when it needs too

it will keep the caster/camber cam bolts from seizing to the inner suspension bushing sleeves too (on the inside only, don’t put it on the exterior cam washer surface).

the standard copper stuff at the auto parts store is useless in comparison, the silver stuff not much better.