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Thread: Exhaust header stud reinstallation issue

  1. #11
    Join Date
    Nov 2016
    Location
    Charlotte, NC
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    2,909
    Man I'm hurting for you here. I can't think of why the nuts wouldn't thread onto the studs correctly. Are they deformed thread locknuts?

    I was going to ask if you checked the flatness of the header flange, but that should only affect the seal, not the nut/stud interactions.

    Mine were far from flat until I ran them on a flat sanding belt

  2. #12
    Join Date
    Jul 2016
    Location
    Austin Texas
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    Quote Originally Posted by ZHPizza View Post
    Man I'm hurting for you here. I can't think of why the nuts wouldn't thread onto the studs correctly. Are they deformed thread locknuts?

    I was going to ask if you checked the flatness of the header flange, but that should only affect the seal, not the nut/stud interactions.

    Mine were far from flat until I ran them on a flat sanding belt
    I’m going to pull them back off today and inspect. Also going to try jacking up the engine slightly and removing the mount on that side. One thought that occurred to me is that maybe the downpipes might be putting too much pressure on them. I had a fitment issue there last time, so I mounted them before doing the final torquing on where they mounted to the block. And the fitment at the downpipes wasn’t very good either. Grr!

    I greatly appreciate the suggestions and support.
    2005 Jet Black ZHP Sedan "Adriana" || TunedByDaniel || BMW Alarm + Fuel Lock || ORION V4s || Eagle Eyes || 435i Coupe Sport Seats || Perforated Leather X5 M-Sport Wheel || FLOW Designs Lip

  3. #13
    Join Date
    Nov 2016
    Location
    Charlotte, NC
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    Oh god yes definitely remove that engine mount and disconnect the rest of the exhaust. This is a good tool to use to support the engine for headers/oil pan gasket/etc: https://www.harborfreight.com/automo...bar-96524.html

    Guarantee someone in Austin has one. We all buy it for one job and stuff it in a closet.

    I had a fitment issue with the catback section too and ended up needing a spacer. Shit was awful. You end up paying a lot for these cheap headers lol

  4. #14
    Join Date
    May 2020
    Location
    Toronto, ON
    Posts
    489
    Quote Originally Posted by ZHPizza View Post
    Guarantee someone in Austin has one. We all buy it for one job and stuff it in a closet.
    This is so true, the one I bought is sitting in some house somewhere in Redwood City. And I haven't lived in Cali since 2017
    2004 BMW 330CI ZHP (well, technically ZAM)


  5. #15
    Join Date
    Jul 2016
    Location
    Austin Texas
    Posts
    225
    I'd like to thank everyone for their suggestions. I redid the whole thing, and took the time to do it in a more correct manner.

    -Removed headers, dropped the rest of the exhaust.
    -Jacked up engine and removed mount on the exhaust side.
    -Got every stud screwed in completely. Ignored the keyed ends and simply used a nut against the collar to drive each one all the way into the block.
    -Test fit the headers on the studs, realized that the 4 corner holes on each header were spaced incorrectly (they were preventing them from sitting flush)
    -Redrilled the corner holes using an 11/32" bit.
    -Replaced the headers and tightened each nut. This time each one tightened completely. Tightened until I couldn't tighten any further.
    -Raised the rest of the exhaust and reattached the downpipes.

    Started car. Giant amounts of smoke from behind each header.

    At this point I'm ready to trash these as well. I have a suspicion that they bolt to the downpipe flanges so poorly that they are actually being pushed away from the block by the rest of the exhaust. Does that theory make any sense? The downpipe flanges are not in the same plane: one is askew AND the lengths of the headers differ by enough that one flange is actually behind the other by about an inch. (!!)

    I'm ready to throw these pieces of garbage away, unless I'm completely missing something. The exhaust gaskets are OEM and are new. Maybe I'll post some pics of the current issues tomorrow?
    2005 Jet Black ZHP Sedan "Adriana" || TunedByDaniel || BMW Alarm + Fuel Lock || ORION V4s || Eagle Eyes || 435i Coupe Sport Seats || Perforated Leather X5 M-Sport Wheel || FLOW Designs Lip

  6. #16
    Join Date
    Nov 2016
    Location
    Charlotte, NC
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    2,909
    The smoke came from the header-head connection or header-exhaust connection?

    Did you check the manifold flanges for flatness? Mine were bowed so bad they never would have sealed without grinding

  7. #17
    Join Date
    Jul 2016
    Location
    Austin Texas
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    Quote Originally Posted by ZHPizza View Post
    The smoke came from the header-head connection or header-exhaust connection?

    Did you check the manifold flanges for flatness? Mine were bowed so bad they never would have sealed without grinding
    Header-head. Checked with a metal straightedge prior and they were flat.
    2005 Jet Black ZHP Sedan "Adriana" || TunedByDaniel || BMW Alarm + Fuel Lock || ORION V4s || Eagle Eyes || 435i Coupe Sport Seats || Perforated Leather X5 M-Sport Wheel || FLOW Designs Lip

  8. #18
    Join Date
    Nov 2016
    Location
    Charlotte, NC
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    Hmm then my only guess would be that the cat back section is prying them away from the head. Hopefully not pulling the threads out.

    Did you notch the heat shield on the motor mount? I had some interference there on one of the headers and cut a little bit off so it would fit better.

  9. #19
    Join Date
    Jul 2016
    Location
    Austin Texas
    Posts
    225
    Quote Originally Posted by ZHPizza View Post
    Hmm then my only guess would be that the cat back section is prying them away from the head. Hopefully not pulling the threads out.

    Did you notch the heat shield on the motor mount? I had some interference there on one of the headers and cut a little bit off so it would fit better.
    No interference with motor mount whatsoever.

    I'm sharing your theory that the downpipes are pulling it away from the head. Again, the flanges at that end are pretty bad as far as alignment goes.

    If it were you--would you try for another cheap eBay set or give up and go for something hopefully better (bimmerbrakes or AA maybe)?
    2005 Jet Black ZHP Sedan "Adriana" || TunedByDaniel || BMW Alarm + Fuel Lock || ORION V4s || Eagle Eyes || 435i Coupe Sport Seats || Perforated Leather X5 M-Sport Wheel || FLOW Designs Lip

  10. #20
    Join Date
    Dec 2019
    Location
    Raleigh, NC
    Posts
    353
    You can get some super high quality Schmiedmann headers for only $235: https://www.schmiedmann.com/en/bmw-E...ct=SCM5254MANI

    The caveat is that you'd need a custom section to connect it to the existing exhaust. Alternatively, their high flow cat section bolts right up to those headers, and you can buy the full set here for a still very reasonable $641: https://www.schmiedmann.com/en/bmw-E...roduct=SCM5254
    330i Base | Mysticblau | Slicktop | 6MT

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