Exhaust Manifold Studs and Bolts - PeachParts Mercedes-Benz Forum

Maddog · #1 01-01-2003, 03:14 PM

I have been trying to get some strong studs and bolts for my exhaust manifold that I can use for my turbo application. Does anyone know of any companies that make hardware like this that will take the temperature and load abuse? Thanks

#2 01-01-2003, 07:08 PM

I'd start with arp - if they don't have 'em ask for a referral.

tvpierce · #3 01-02-2003, 10:16 PM

I just changed the studs and bolts on my Volvo turbo. The studs are not hardened, and the nuts are copper. I used high temp anit-sieze on studs and bolts to ensure easy disassembly in the future.

I've been told that you don't want to go with a hardened stud, because if it does ever break off (someday) you want to have a softer metal that can be drilled out by a machine shop.

I'm not an expert on the subject, I'm just passing along some food for thought.

Jeff Pierce

Maddog · #4 01-02-2003, 10:18 PM

Well I would even love to know where I could get replacement OEM studs and nuts. Can anyone answer that?

tvpierce · #5 01-03-2003, 11:32 AM

This must be for the 190E "Internationalle". What is your power plant... American or German??? I would be very surprized if you couldn't find a match, regardless of nationality, at NAPA.

If not, then maybe this is a job for Phil (at Mercedes Shop at the top of this site. The call is toll free, and he is fantastic to work with). I'd bet he could find you exactly what you're looking for.

Additionally, here's a resource for fasteners online: http://www.boltdepot.com/

Good luck.

Jeff Pierce

Speedtek · #6 01-03-2003, 11:57 AM

If the turbo is properly supported you should have no problem with broken studs. When tightening the manifold do it evenly.
Many mechanics tighten one side then they tighten the other side warping or putting abnormal stress on the studs. use all the same type of nuts and washers so that the expansion rate is the same. Copper-coated nuts are great, just use new ones everytime. I have some special washers that lock the nuts on.
but prevent loosening.

So the key is to support the manifold and not let the weight of the turbo ride on the studs.

tvpierce · #7 01-03-2003, 12:53 PM

My concern with broken studs has nothing to do with installation or even how the manifold is supported. But 8-10 years from now, when you need to remove the manifold -- say to replace a failed manifold gasket -- the studs and/or nuts may have sufficient corrosion to cause them to stick. Then the twisting force being applied to the nut causes the stud to break. In my experience, that's when exhaust studs fail most frequently.
Which is why I HIGHLY suggest high temp anti-seize on both the stud and the nut.

Jeff Pierce

Speedtek · #8 01-03-2003, 03:16 PM

I recommend anti-seize also. Where you live could also be the problem. I live in Hawaii surrounded by SALT WATER. studs corrode and break all the time. On most of my installations I use studs from BMW and also the copper nuts. VW uses the same studs but the dealer charges more. I use to buy from metricman in California. I have taken apart customer cars theat had turbos on them for over 10 years. maybe 1 stud out of 30 will break and those are the ones that are rusted. Most of the time oil from the valve cover leaks onto the studs and those come off the easiest and the studs still look new. You might try studs from a Honda.
They are hard and plated. But we have never had to remove a turbo from a Honda in the long run. They are usually taken apart before that.

Maddog · #9 01-03-2003, 07:36 PM

I will run over to napa sometime and see what they have for studs. The studs are for a 1990 300E engine. How would I find the equvalent in a BMW stud or a Honda stud?

Speedtek · #10 01-03-2003, 09:27 PM

go to the dealer they stock them. (Honda and BMW) should be 8mm x 1.25mm shoulder studs. either 38, 40 or 48mm long.

I would be wary of NAPA stuff. not the same grade as stock.

Get the copper nuts from BMW they have 12mm and 13mm socket size. The washers on the 300e are nice and thick.

Tobias MB · #11 01-06-2003, 01:18 AM

In times past....we used to replace the exhaust studs on 911s because you could easily destroy a cylinder head if it broke and took some head material with it. This would also cause a partial engine teardown.....expensive!
So the trick is to find a one meter length of threaded stainless steel metric rod and make your own studs but still use the copper BMW or VW nuts with them. This always works no matter how long the nuts are on!

Tobias MB
4 MBs

Maddog · #12 01-20-2003, 10:41 PM

Speedtek, what would you recommend using to make a bracket to support the exhaust manifold? My manifold is pretty heavy as I made it from thick strong steel. How thick should the steel I use for the backet be? Thanks man!

Speedtek · #13 01-20-2003, 11:21 PM

We try to use 1/4" thick steel or 3/8" Steel rod. Try to use tempered steel. The mild stuff always cracks. Sometimes we try to use bracket material for other cars. "make it fit"
Steel rod is mostly rolled so it is pretty tough.

REMEMBER: Some support is better than NOTHING!