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Thread: Exhaust studs

  1. #1

    Exhaust studs


    Last night I removed my heat exchangers as part of an SSI upgrade on my 70S motor (not a 70S car though) and pretty much all of the barrel nuts came out complete with the studs still rusted firmly in place So my question is do I simply reinstall these barrel nuts with the studs rusted on (essentially they are now barrel bolts) or should I try and source new studs from local dealer? Pros/Cons?

    I'll post some pics of the project soon

    Doug Roberts
    68 912 Slate Gray
    64 356C Ivory

  2. #2
    At the very minimum, replace with new studs and barrel nuts along with a nice layer of anti-seize lube. You can obtain these from various aftermarket sources as well as from Porsche.

    Beyond this, you can also install copper barrel nuts as well as stainless steel studs to reduce corrosion effects. You were fortunate they came out instead of breaking.


  3. #3

    very lucky...

    I was actually very excited that none of them broke I think I am going to see if I can pick up the new studs today. Are you suggesting I use the anti seize on the stud to head joint or the nut to stud joint or both?

    Doug Roberts
    68 912 Slate Gray
    64 356C Ivory

  4. #4
    Not sure what the "books" recommend. I've done both. Since the studs are under tension, I don't think the studs will have any problem staying in the cylinder head. In fact, attempted corrosion tries to take care of most of that. Therefore, I'd say to use antiseize on both ends and torque the barrel nuts to specs. If you decide you must use a thread locking compound, use the mildest type you can find (blue).

    Hope this helps,

  5. #5
    don't chain me to the pole and beat me, but the studs are installed in to the heads with red locktite. ( thats probably why everyone breaks them pulling the barrel bolts off ).

    i never buy a thing from the dealer. i hate to do a shamless plug, but the nuts are here. you'll have to call for studs.
    72 911t * 74 914 2.0

  6. #6

    Exhaust studs and anti-seize

    I used the anti-seize on the stud threads @ the barrel-nut area. I figured that the anti-seize is to prevent the nut from 'seizing' on the stud. When you remove the barrel-nut, hopefully it comes off by itself, and does not pull the exhaust stud out of the cyl. head (and add to the 'barrel-stud/bolt' population/pile).
    If you need to reinstall the exhaust studs into the cyl. head:
    1) clean the threads in the cyl. head and the on the stud,
    2) double-nut (install two hex nuts on the stud and tighten them
    against each other) the stud so you can use a wrench or
    socket to snug the exh. stud into the cyl. head (do not torque
    the stud into the cyl. head).
    3) use Loc-tite Red (a drop or two) on the stud threads (only on
    the threads that go into the cyl. head).
    4) use/coat the barrel-nut area stud threads with anti-seize
    before installing the heat exchanger.
    Sound good? HTH.
    FWIW, instead of using barrel nuts, I used brass hex nuts. I think that there is less of a chance of corrosion (no rust). The brass nuts need to have a wrench size of 12mm and I used a
    Snap-on 1/4" drive, 12 point (thinner side wall) chrome (non impact) socket. I did this a long time ago on 914-6 heat exchangers; I haven't gotten around to the S yet. I don't think that there should be a problem/difference. Any ideas?

  7. #7

    thanks for the thoughts..

    That's pretty much exactly what I ended up doing (with regard to the stud anti sieze/loctite combo) although I did use the barrel nuts for all of the through exchanger studs.

    And now for a rant:

    The only sticking point was the alignment of the passenger side exchanger. It was just slightly off alignment, and once installed the forward most through the exchanger hole did not line up perfectly with the barrel nut head (off by maybe 1mm). The tool I had bought from Pelican to reach these barrel nuts was WAY thicker in circumferance than it needed to be (read barely fit through the exchanger holes) which gave no wiggle room to access the off alignment barrel nut. This took hours to sort out with numerous trips to the tool store to finally come up with a solution. The solution was a 9" tee handled 8mm hex wrench with the rounded hex tip sliced off by my dremmel

    All in all a lengthly but worthwhile project, sounds great with the stock exhaust and a 2.2S motor.

    I've got some pics of the process if anyone is interested I'll post em.
    Doug Roberts
    68 912 Slate Gray
    64 356C Ivory

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