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Missing bolt - exhaust manifold to turbo
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chuck21401  



Joined: 20 Feb 2005
Posts: 241
Location: Annapolis, MD

PostPosted: Mon Sep 23, 2019 6:08 am    Post subject: Missing bolt - exhaust manifold to turbo Reply with quote

Was looking under the hood today and noticed that I'm missing an important bolt. Yikes. Guess the good news is that the bolt head didn't snap off. So either it backed out of there or wasn't reinstalled when the turbo was bolted back on?

Looking at the parts diagram...I'm missing the bolt (931-123-197-00) and sleeve (931-123-199-00). Only $75 from the dealer.

The other bolt that I can see doesn't seem nearly as exotic...it is holding down a regular washer rather than a sleeve. Wondering if I could use generic metric hardware here.


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924RACR  



Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA

PostPosted: Mon Sep 23, 2019 9:49 pm    Post subject: Reply with quote

Yeah, relatively generic would be fine - though I'd aim for grade 8.8 at least. And for sure a lockwasher, those bolts like to come loose.
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Vaughan Scott
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Cédric  



Joined: 27 Aug 2004
Posts: 1976
Location: Sweden

PostPosted: Mon Sep 23, 2019 10:56 pm    Post subject: Reply with quote

I would say try to avoid generic hardware, its a bad idea for the turbo joint. These bolts are very high spec, especially on turbo engines, since normal steel bolts loses alot of clamping force with the heat. The spacer i also important as it need a material which expands in similar fashion as the other materials in the joint the keep the clamping while its hot.

The prices are mad on these bolts from porsche. I have used turbo bolts and spacers from Scania 730 truck, since I know the spec on those (I worked with this years ago), but you dont have those over there.

An alternative is to just look at other OEMS and tryck to find similar screws from other turbo joints (All OEM turbo screws are most likely fairly high spec). Thats how i bought my exhaust manifold-head studs, waste gate studs and nuts etc, its all from the VAG exhaust parts catalouge.
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1940
Location: MI

PostPosted: Tue Sep 24, 2019 3:41 am    Post subject: Reply with quote

I broke 2 of the 3 of them the first time I removed my turbo and then ran grade 8 black allen head bolts for a while..

I was able to acquire 2 more turbo bolts in parts lots I have bought here over time and have been running with 3 original bolts for a while now..

I'd try to buy them from guys here that have parted turbo cars if I was you.. Or what Cedric said is a pretty good idea too..
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chuck21401  



Joined: 20 Feb 2005
Posts: 241
Location: Annapolis, MD

PostPosted: Tue Sep 24, 2019 6:11 am    Post subject: Reply with quote

Thanks for the comments and ideas. I think I'll buy the Porsche parts to replace the missing bolt and sleeve. I'm just not going to tell my wife how much I paid for them.

Good idea about buying them when turbo cars get parted out. I found some old classified ads on Pelican and Rennlist when I ran searches on the part numbers. So I'll replace the other two bolts over time. One bolt looks easy to remove and replace, the other one was obscured by the exhaust manifold...hopefully that one is accessible without removing the engine or something.

I found a picture of the bolt in the classic porsche parts catalog, the other bolt installed on my car doesn't look like this. Ack. So I'm guessing I need a special metric 12point socket to tighten the bolt?


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Svobodin  



Joined: 08 Oct 2013
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PostPosted: Tue Sep 24, 2019 6:50 am    Post subject: Reply with quote

On my 1980 931 two of those were studs and the obscured one was a bolt. Guess they updated that for 1981.
I will say those bolts/studs were probably the worst part of replacing the turbo. Could not get them to align at all (stud came out with the nut so essentially acted like a bolt) while holding the turbo up at the same time, not fun!
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1973
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PostPosted: Tue Sep 24, 2019 8:25 am    Post subject: Reply with quote

I swapped my OEM 12 point bolts of some fancy material for 3 high quality studs with Allen heads to help tighten, reused the 3 OEM inconel or similar sleeve washers which are NLA, all tightened with high quality stainless lock nuts. Survived 4yrs of abuse before being replaced again earlier this year when swapping out the turbo. The replacement studs and nuts were circa £50 a set. The OEM 12 point bolts are circa £30 each. They are not regular steel.
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924RACR  



Joined: 29 Jul 2001
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PostPosted: Wed Sep 25, 2019 3:30 am    Post subject: Reply with quote

Dunno about the sleeves, I must be missing them, but perhaps some fancy ARP stainless bolts would work well:
https://arp-bolts.com/kits/arpkit-detail-b.php?RecordID=3529
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Vaughan Scott
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chuck21401  



Joined: 20 Feb 2005
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PostPosted: Wed Sep 25, 2019 4:15 am    Post subject: Reply with quote

I ordered one set from Porsche. Will wait on replacing the other two.
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chuck21401  



Joined: 20 Feb 2005
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PostPosted: Wed Sep 25, 2019 4:31 am    Post subject: Reply with quote

924RACR wrote:
Dunno about the sleeves, I must be missing them, but perhaps some fancy ARP stainless bolts would work well:
https://arp-bolts.com/kits/arpkit-detail-b.php?RecordID=3529


Nice find. The Porsche bolt is listed as 10 X 37 in the description. I'm guessing that the sleeve is in the neighborhood of 7mm. Will take some pics when the exotic parts arrive.

I think the original bolt must have worked its way loose.
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Carrera RSR  



Joined: 08 Jan 2010
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PostPosted: Wed Sep 25, 2019 6:06 am    Post subject: Reply with quote

The manifold to turbo bolts make a break for freedom at every chance possible
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chuck21401  



Joined: 20 Feb 2005
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Location: Annapolis, MD

PostPosted: Wed Sep 25, 2019 10:17 am    Post subject: Reply with quote

chuck21401 wrote:
I ordered one set from Porsche. Will wait on replacing the other two.


Ack...update from the dealer.

Thank you for your order. Unfortunately part number(s) 931-123-199-00 is being sourced from Germany. Standard shipping for this item will take approximately 4-5 weeks to arrive

So will order the ARPs to hold things together for now. I also need to crawl under the car to see if anything else is loose.
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924RACR  



Joined: 29 Jul 2001
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PostPosted: Wed Sep 25, 2019 9:56 pm    Post subject: Reply with quote

Ew!

Yeah, I had a bitch of a time trying to get everything to stay tight. Stage 8 kit worked well, but corroded unpleasantly with the heat - pretty much had to pitch it all when I took it apart. Last round of assembly was using stock copper lockwashers from Bel-Metric... haven't had a lot of miles since, though, and that was only this summer.

I do find it amusing that there's even a procedure in the factory manuals on how to check torques on the turbo downpipe studs/nuts...
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chuck21401  



Joined: 20 Feb 2005
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Location: Annapolis, MD

PostPosted: Sun Sep 29, 2019 4:56 am    Post subject: Reply with quote

The ARP bolts worked out well.

I replaced the missing bolt...and realized that the other bolt was finger tight!



So I replaced that one too.
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chuck21401  



Joined: 20 Feb 2005
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PostPosted: Mon Oct 07, 2019 5:11 am    Post subject: Reply with quote

Update - another bolt disappeared and the second one backed out 3/4 of the way. I was using lock washers.

The good news is that the missing bolt was ARP and not the special bolt/sleeve ($$$) that I ordered from Porsche.

What else could be going on here? Both bolts tightened down as they should so I don't think that the threads are stripped. Maybe the turbo isn't tight enough and is shaking things loose? Also don't know about the third bolt or stud behind the exhaust manifold.
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