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Missing bolt - exhaust manifold to turbo
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1807
Location: Somerset, UK

PostPosted: Mon Oct 07, 2019 8:06 am    Post subject: Reply with quote

Heat cycles and vibration is not your friend with bolts unless lock wired.

I use studs with hex so I can tighten them in before using lock nuts with the OEM sleeves to help with the heat cycles.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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CÚdric  



Joined: 27 Aug 2004
Posts: 1884
Location: Sweden

PostPosted: Mon Oct 07, 2019 7:14 pm    Post subject: Reply with quote

Sound weird, are you sure theres not a semi deteriorated gasket in there ?

I only torque mine ones, and then they are set.
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chuck21401  



Joined: 20 Feb 2005
Posts: 133
Location: Annapolis, MD

PostPosted: Mon Oct 14, 2019 7:22 am    Post subject: Reply with quote

Bolt 93112319700 and Sleeve 93112319900. At $85 I'm not sure I want to install these until I figure out why the bolts keep backing out and disappearing.






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Last edited by chuck21401 on Mon Oct 14, 2019 8:27 am; edited 1 time in total
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chuck21401  



Joined: 20 Feb 2005
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Location: Annapolis, MD

PostPosted: Mon Oct 14, 2019 7:32 am    Post subject: Reply with quote

CÚdric wrote:
Sound weird


I was thinking the same thing...and after crawling under the car I have multiple suspects.

3 out 4 studs holding the turbo to the exhaust have gone missing.



1 of 2 bolts missing from turbo mounting bracket. (apparently there are four total...need to check on the other two)



This one is hard to see, but missing the 3rd bolt that connects the exhaust manifold to the turbo (I've already replaced the two bolts on the other side).


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Last edited by chuck21401 on Mon Oct 14, 2019 9:20 am; edited 1 time in total
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1769
Location: MI

PostPosted: Mon Oct 14, 2019 7:58 am    Post subject: Reply with quote

Wow, more torque next time partner..
I think the turbo to block mount i supposed to have 4 bolts into the block isn't it?

When installing new studs I'd torque them into their holes a bit too..
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chuck21401  



Joined: 20 Feb 2005
Posts: 133
Location: Annapolis, MD

PostPosted: Mon Oct 14, 2019 8:14 am    Post subject: Reply with quote

I can replace the missing bolts on the turbo mounting bracket and the turbo to exhaust manifold....but what to do about the studs from the turbo to the exhaust? Would I have to remove the exhaust, install new studs, then tighten everything?

I checked the parts diagram...the studs are 90008105002 and the nut is N90073001 and that it is a lock nut. Some websites listed the studs as NLA but others seem to indicate they have them in stock.
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1981 Porsche 931


Last edited by chuck21401 on Mon Oct 14, 2019 8:23 am; edited 2 times in total
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chuck21401  



Joined: 20 Feb 2005
Posts: 133
Location: Annapolis, MD

PostPosted: Mon Oct 14, 2019 8:21 am    Post subject: Reply with quote

Fasteddie313 wrote:
Wow, more torque next time partner..




Some good news...the j pipe and wastegate nuts were all still tight when I checked them.

Quote:
I think the turbo to block mount i supposed to have 4 bolts into the block isn't it?


Yeah, I think you are correct, I'm looking at the parts diagram and see that the bracket has four bolts...I need to look under the car again...hopefully the other two have not gone missing.

Quote:
When installing new studs I'd torque them into their holes a bit too..


So that's the question...can that be done without disassembling everything either with a stud installer or the double nut trick?
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Fasteddie313  



Joined: 29 Sep 2013
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PostPosted: Mon Oct 14, 2019 9:12 am    Post subject: Reply with quote

Well.. To me logic would suggest that if they had room to fall out then they should have room to go back in..

And they are just studs.. Prolly M10X1.5 or something like that, find a nut that fits them and take that to match up..
Get some from the hardware store, black ones which are probably grade8..
I wouldn't be concerned with getting whatever the Porsche part numbered ones are..

I would definitely try it without removing the exhaust but it might be tricky..
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Carrera RSR  



Joined: 08 Jan 2010
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PostPosted: Mon Oct 14, 2019 6:30 pm    Post subject: Reply with quote

Get high grade studs with a hex end so you can torque them down tight with an Allen key. Use lock nuts on the exhaust parts.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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CÚdric  



Joined: 27 Aug 2004
Posts: 1884
Location: Sweden

PostPosted: Mon Oct 14, 2019 8:07 pm    Post subject: Reply with quote

I cant do mine on the turbine outlet without backing the exhaust. It looks strange that there are washers under the nut on the turbine outlet, those studs look home made aswell. I use lock nuts copper coated from the VAG catalouge there, they never back out and are cheap.

One things i noticed is that you have the old type gasket on the outlet, which you shouldnt have, if you have an s2 with the later turbine housing. Then the next question is what type of gasket is it in the turbo to manifold joint, it might be the old type there aswell, if it is its definitely blown out, so you will probably re torque those bolts very frequently until you get a fresh and correct gasket in there. The gasket should be like a small steel ring which sits in a groove. Seems like the turbo was changed and everything didnt really come together as it should have been done, neither correct hardware or torque/torquing sequence. There is a certain sequence how everything should be torqued together aswell, if you dont have it I can send it.
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1807
Location: Somerset, UK

PostPosted: Mon Oct 14, 2019 8:55 pm    Post subject: Reply with quote

CÚdric wrote:
I cant do mine on the turbine outlet without backing the exhaust. It looks strange that there are washers under the nut on the turbine outlet, those studs look home made aswell. I use lock nuts copper coated from the VAG catalouge there, they never back out and are cheap.

One things i noticed is that you have the old type gasket on the outlet, which you shouldnt have, if you have an s2 with the later turbine housing. Then the next question is what type of gasket is it in the turbo to manifold joint, it might be the old type there aswell, if it is its definitely blown out, so you will probably re torque those bolts very frequently until you get a fresh and correct gasket in there. The gasket should be like a small steel ring which sits in a groove. Seems like the turbo was changed and everything didnt really come together as it should have been done, neither correct hardware or torque/torquing sequence. There is a certain sequence how everything should be torqued together aswell, if you dont have it I can send it.


Same here, I cannot get the two lower nuts off the turbo to exhaust flange without pulling the exhaust back. No way could I get a stud in or out with exhaust on.

Old exhaust, now using custom stainless but similar fixings
Untitled by stevenmcooper, on Flickr

As for manifold to turbo joint, I have never used the later fire ring and not blown out a gasket. But I do use new gaskets.

Quality hardware is a must to avoid breakages, backing out and leaks...
Untitled by stevenmcooper, on Flickr

Fresh studs and lock nuts going in earlier this year when upgrading the turbo...

Untitled by stevenmcooper, on Flickr
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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chuck21401  



Joined: 20 Feb 2005
Posts: 133
Location: Annapolis, MD

PostPosted: Tue Oct 15, 2019 1:52 am    Post subject: Reply with quote

CÚdric wrote:
I cant do mine on the turbine outlet without backing the exhaust. It looks strange that there are washers under the nut on the turbine outlet, those studs look home made aswell. I use lock nuts copper coated from the VAG catalouge there, they never back out and are cheap.

One things i noticed is that you have the old type gasket on the outlet, which you shouldnt have, if you have an s2 with the later turbine housing. Then the next question is what type of gasket is it in the turbo to manifold joint, it might be the old type there aswell, if it is its definitely blown out, so you will probably re torque those bolts very frequently until you get a fresh and correct gasket in there. The gasket should be like a small steel ring which sits in a groove.



It's coming back to me now. When I reinstalled the exhaust the last time, I wasn't able to start one or more of the nuts without shifting the exhaust back at least a 1/4 inch. From the older thread:



Again from the older thread, yes, had washers and regular nuts. One of the studs came out as I dissembled everything.


Here is the turbo:


k26-2664 G4.10 So I believe the turbo is 1980.
The car is a 1981 931 but the engine and transmission are 1980. Except it has a the S2 charge tube.

I remember the gasket between the turbo outlet and the exhaust, it did have small steel ring. I have no idea what type of gasket is between the turbo and the exhaust manifold. Getting to that gasket might be a challenge. Shoot.

Quote:
Seems like the turbo was changed and everything didnt really come together as it should have been done, neither correct hardware or torque/torquing sequence. There is a certain sequence how everything should be torqued together aswell, if you dont have it I can send it.


I found this...but it only covers re-installation of the turbo. The info I have about removing/re-installing the WG doesn't lay out a sequence on how everything should be tightened down....so if you have more info that would be helpful.


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chuck21401  



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PostPosted: Tue Oct 15, 2019 2:13 am    Post subject: Reply with quote

Carrera RSR wrote:

Quality hardware is a must to avoid breakages, backing out and leaks...


I can see why that is important now.
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chuck21401  



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PostPosted: Tue Oct 15, 2019 3:20 am    Post subject: Reply with quote

Carrera RSR wrote:
Get high grade studs with a hex end so you can torque them down tight with an Allen key


Very nice. Source? I'm searching around and can't seem to find anything like those. What length?

Untitled by stevenmcooper, on Flickr[/quote]
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Carrera RSR  



Joined: 08 Jan 2010
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Location: Somerset, UK

PostPosted: Tue Oct 15, 2019 3:55 am    Post subject: Reply with quote

chuck21401 wrote:
Carrera RSR wrote:
Get high grade studs with a hex end so you can torque them down tight with an Allen key


Very nice. Source? I'm searching around and can't seem to find anything like those. What length?


I have no idea. I take old hardware to my local nut and bolt store and walk out with new equivilents. PET might give specs
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
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