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Paynewright
Monza


Joined: 17 Apr 2018
Posts: 204
Location: Nr Lutterworth Leics


PostPosted: Tue Aug 20, 2019 10:18 pm    Post subject: Reply with quote

Demort,

What do you replace the rusty blobs with? OEM spec bolts or something else?

I think if going for OEM bolts they should be on a 2 year change strategy.

Any other hints and tips?

Ian
 
  
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g911omr
Spa-Francorchamps


Joined: 29 Sep 2009
Posts: 287



PostPosted: Wed Aug 21, 2019 9:18 am    Post subject: Reply with quote

The exhaust bolts on my car were replaced with stainless studs/nuts by the previous owner at 50,000 miles about 3 years ago. I can't see the logic of doing otherwise. The original bolts had lasted 16 years though and probably would have been fine for a few more had he not wanted different manifolds.
 
  
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Luddite
Nürburgring


Joined: 18 Dec 2018
Posts: 441
Location: Scotland


PostPosted: Wed Aug 21, 2019 11:26 am    Post subject: Reply with quote

In the 80`s while working on my 60`s rotted old 912, the thing that impressed me was that all the fixings came loose without brakeage which came as a great surprise having had many years experience of fixing failures when trying to loosen fixings on all sorts of older Brit cars.

Even when I progressed to 911 ownership by way of a seventies SC the quality was still there, as it was in my last 911 an early 80`s SC on which I replaced the exhaust system...

A friend has a 964 and a 997, and is up against the broken studs issue on his 997, was engaged in buying the drills jigs and studs process the last time we were in contact...

Sorry guys but my confidence in Porsche engineering has taken a hit since joining this forum.. Jeez even on a rotten Mini I would expect those brass exhaust nuts to come loose and BL never touted themselves as the pinnacle of quality automotive engineering..???

I worked in a non non automotive environment where stainless fixings were used in alloy equipment that was exposed to weather over many years.... Just about every fixing could not be persuaded to move without damage if they had been in situ for more than a couple of years...

Coincidentally my old sports car with it`s Rover V8 had all it`s fixings replaced with SS when it was rebuilt circa 16 years ago, which has been a boon when taking things apart.... As the result of this thread I went out to the garage and put a spanner to one of the SS exhaust flange to alloy head bolts this morning.... it loosened without issue, though I only cracked it by less than a flat, to be sure it would loosen, trying to avoid disturbance to the gasket below..

Interesting thread guys but keep it friendly please.. Thumb
 
  
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crash7
Hockenheim


Joined: 28 May 2011
Posts: 649



PostPosted: Wed Aug 21, 2019 11:45 am    Post subject: Reply with quote

Titanium manifold studs for me with K Nuts. - I also replaced the manifold to cat bolts for titanium, again with K nuts.

I suspect it will be years before any useful feedback can be gained, I am however optimistic that they will never corrode like the standard Porsche items!
 
  
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Hertsdriver
Spa-Francorchamps


Joined: 12 Nov 2018
Posts: 325
Location: Hertfordshire/London

2004 Porsche 997 Carrera 2

PostPosted: Wed Aug 21, 2019 11:48 am    Post subject: Reply with quote

The parts manuals seem to indicate that early 996 had bolts 900 378 131 00 , and these then changed to 999 075 071 00.
999 075 074 00 are used on the 997.1, and 999 073 471 01 on 997.2

All 4 it would seem are made of cheese Dont know
 



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Guywilko
Trainee


Joined: 04 Jul 2017
Posts: 53



PostPosted: Wed Aug 21, 2019 12:38 pm    Post subject: Reply with quote

crash7 wrote:
Titanium manifold studs for me with K Nuts. - I also replaced the manifold to cat bolts for titanium, again with K nuts.

I suspect it will be years before any useful feedback can be gained, I am however optimistic that they will never corrode like the standard Porsche items!


Ditto re PPBB's Ti studs!!

Do you have a link for the manifold to cat bolts plse?
 
  
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crash7
Hockenheim


Joined: 28 May 2011
Posts: 649



PostPosted: Wed Aug 21, 2019 2:37 pm    Post subject: Reply with quote

I think I bought them from these guys..,

https://raceboltuk.com/titanium-bolts-nuts/

or perhaps these

https://www.pro-bolt.com/titanium.html

However regardless of where you get them you need M8x30mm Flanged bolts and M8 K Nuts, 6 off of each.
 
  
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jond58
Monza


Joined: 19 Jun 2017
Posts: 195



PostPosted: Wed Aug 21, 2019 6:01 pm    Post subject: Reply with quote

I get the Porsche criticism and I’m not defending the indefensible but.........the earlier cars were low production number vehicles but as a company by the time the 996 were been produced they were in a financial pickle. Something had to change and I think the 996 marks a line in the sand where component and build costs were a deciding factor in lots of areas. My exhaust manifolds are toast and I now how have all the parts to replace. It’s either going to cost me some significant money or some significant time if I do it myself. Sure Porsche should have fitted studs and nuts (copper or brass) but the cost of the bolts across how ever many cars probably kept the accountants happy. Had they carried on with a ‘hand built’ approach would they be here today? Or would they be Chinese owned?? It’s a massive pain in the arse and pretty annoying to say the least but what can you do?!? I’m much more used to working on motorcycles so having done exhaust plenty of times previously I’ll fit steel studs with copper or brass nuts (I have loads of these!) and have done this with success on the bikes. I’d recommend aluminium paste for the studs as it’s high temp resistant!!
 
  
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deMort
Dijon


Joined: 21 Mar 2015
Posts: 7176
Location: Brighton


PostPosted: Wed Aug 21, 2019 7:00 pm    Post subject: Reply with quote

Paynewright wrote:
Demort,

What do you replace the rusty blobs with? OEM spec bolts or something else?

I think if going for OEM bolts they should be on a 2 year change strategy.

Any other hints and tips?

Ian


We use stainless steel bolts , nuts .. we buy in bulk , not sure where from but probably the same ones you would source from ECP , Design etc .

Need to remember though .. the original 996 ones ( not stainless ) have lasted 10 years ish on average .. some more , some less .. but as an average .. 997 and id probably drop that to 8 .. G2 6 .. best i stop there Very Happy

The way garages change them is going to be very different from at home and on stands ..

We have ramps , finger sanders , special air hammers and most importantly .. Oxy acetylene bottles .

First off .. with Any stainless nut/bolt you Have to use ally grease on the threads .. if not once done up they will never come undone again .

Been there done that .. Embarassed

At work .. i can use a finger sander to remove the original flat side of the head ( model dependant ) .. heat it up ( cherry red ) , the flange .. NOT the bolt and either hamer / punch it out or use an air hammer with a long reach end to punch them out , an excellent tool .. dot punch the bolt , then heat then attack it .. literally 6 seconds and it's on the floor !

Or depending on model i'll heat up what's left of the nut ( cherry red ) then chisel it off .. then heat up the flange and knock it out .

Rule of thumb .. all 6 flange bolts replaced is approx 2 hrs labour charge plus parts ..

There are some jobs i tend to say .. just pay a garage to do and this is one of them .. it's just a huge struggle at home , on stands and without the equipment we have .. i for one wouldn't contemplate it should i be in your shoes .

I'm all for helping out here and trying to give advise the best i can .. this is one job that there is no easy answer to .

I'll also add .. its possible to kill a lambda sensor due to the shock of hitting the exhaust too much .. that's a cost that also needs to be factored in .. garage or at home .

Finger sander to give you an idea ..


https://www.amazon.co.uk/Silverstorm-247820-260W-13mm-Power/dp/B00J8UITSS/ref=asc_df_B00J8UITSS/
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jond58
Monza


Joined: 19 Jun 2017
Posts: 195



PostPosted: Wed Aug 21, 2019 7:27 pm    Post subject: Reply with quote

I’d entirely agree with demorts advice! I have a unit with a four post lift, as many tools as most garages and a mate who’s a powerstation engineer on standby and to be honest I might just farm it out to my Indy because it such a potential pain in the arse!!
 
  
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Paynewright
Monza


Joined: 17 Apr 2018
Posts: 204
Location: Nr Lutterworth Leics


PostPosted: Wed Aug 21, 2019 8:34 pm    Post subject: Reply with quote

Demort,

Is that manifold to catalyst pipe or manifold to head? I was referring to the head bolts.

Luckily, the manifold/catalyst bolts had been changed before on my car so no problems knocking them out - 1 hour to do all 6!

Its the 12 manifold to head bolts I’m interested in.

Ian
 
  
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Hertsdriver
Spa-Francorchamps


Joined: 12 Nov 2018
Posts: 325
Location: Hertfordshire/London

2004 Porsche 997 Carrera 2

PostPosted: Thu Aug 22, 2019 2:36 pm    Post subject: Reply with quote

deMort wrote:

First off .. with Any stainless nut/bolt you Have to use ally grease on the threads .. if not once done up they will never come undone again .

Been there done that .. Embarassed


I know you were talking about the flange bolts rather than the manifold bolts, but this is still very good advice. Stainless nuts on stainless threads are a recipe for disaster Thumb
 
  
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Wh1t3Kn1ght
Monza


Joined: 22 Aug 2018
Posts: 216


2001 Porsche 996 Carrera 2

PostPosted: Thu Aug 22, 2019 6:17 pm    Post subject: Reply with quote

Spot on topic - I started to sort out my exhaust manifold flanges and to replace the back boxes last weekend. Most of it came apart fairly easily which was a relief - needed to borrow the neighbours angle grinder to get the cat to silencer clamps off. The nuts on the flanges had completely corroded bar one little blob of metal on each flange so after I ground that off they came apart. The studs however were firmly welded into the cat flange so I dropped them off at a local garage to be removed. The guy there suggested he also remove the lambda sensors so I could refit them with fresh grease.

Well its been a couple of days and I called him up today and he told me he had to smash the lambda sensors to get them off. Needless to say I wasn't best pleased, he has apologised that he didn't contact me before destroying them. And no I won't be going there again... he did however use an interesting way of removing the studs by making a slit through the flange on each stud to release the tension so they would come out.

Unfortunately now I'm going to have to wait until next week for new lambda probes as Opie are awaiting stock and cp4l also quoting long delivery time... So bang goes the idea of getting the exhaust all back together on Saturday frustrated


_________________
2000 Violet 911 Carrera 2 3.4
1990 Panther Black 944 Turbo
 
  
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Paynewright
Monza


Joined: 17 Apr 2018
Posts: 204
Location: Nr Lutterworth Leics


PostPosted: Thu Aug 22, 2019 6:49 pm    Post subject: Reply with quote

Thats a proper bodge all round. I’d be fuming!!
 
  
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deMort
Dijon


Joined: 21 Mar 2015
Posts: 7176
Location: Brighton


PostPosted: Thu Aug 22, 2019 7:42 pm    Post subject: Reply with quote

I'll just say i've seen the slit on Boxsters several times .. not something i've ever had to do or really think much of .. but what's done is done .

As a mechanic im well aware we have different ways of doing things .. i see it at work every day .. but not all ways are the best .

Exhaust manifolds are a typical example of this .. we mechanics all have different ways of getting them out .. we all also swear ours are the best ways lol .

So .. manifold studs ..

Some guys heat the bolt before trying to remove it .. oxy acet or a coil based electric heater .

Some guys hit the bolt with a hammer / punch .

Some have an air gun that is more shock based .

Some do them up slightly before trying to remove .

I use a gun that's more impact based .. ingersoll rand and do them up slightly then gun them out .

When they snap ..

I will try and weld a nut onto the stud first and see if i can get it out... if not

i prefer to use a finger sander , get the bolt flat and use a jig .

my colleague on the ramp next to me .. he dot punches the bolt , uses a pump up axle stand to rest the drill on then free hand drills them out ..

Hes did 8 snapped bolts the other day .. all free hand .. tapped .. time sert and job done .. i almost clapped !

Some guys are better than others .. hes better than me by a long shot !

Basically there is no set way of doing these im afraid .
_________________
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My Daughter's Crowdfunding has hit the target see Here

Thank you all so Very much .

She's not going until july 2020 though .



Mechanic

7pm - 9pm

Now At An Indy.
 
  
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Wh1t3Kn1ght
Monza


Joined: 22 Aug 2018
Posts: 216


2001 Porsche 996 Carrera 2

PostPosted: Thu Aug 22, 2019 9:13 pm    Post subject: Reply with quote

Can't see the slit method being a problem as the metal of the flange seems pretty solid (and thick). The only bodge really was when he destroyed the lambda probes.... I didn't ask if he'd ever heard of a lambda socket Floor

The studs were pretty well stuck in - I was going to see what I could do with my torch but thought it better to pay someone else. I did try drilling one of them with some good bits but didn't fancy sitting there for 10 mins+ for 6 x bolts..

Used to have an awesome local garage when I was younger would be great to find another just for those crappy jobs like this that you can just get someone you trust to do it. Doesn't have to be a Porsche specialist just a decent mechanic thumbsup
_________________
2000 Violet 911 Carrera 2 3.4
1990 Panther Black 944 Turbo
 
  
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jond58
Monza


Joined: 19 Jun 2017
Posts: 195



PostPosted: Thu Aug 22, 2019 9:23 pm    Post subject: Reply with quote

As the bolt or stud is subjected to loads of heat cycles in the vehicle this effectively welds them in real tight, due to the location and the fact that you’re not spraying the part that’s actually stuck all the plus gas/Kroil/pb blaster in the world isn’t going to solve the problem. It will however help. I have an induction coil and I’ve used it with success but never tried manifold studs. The problem with the 996 is that they’ll have corroded between the exhaust flange so effectively locked in tight and then weaker further up to the bolt head. Hence why they snap!! This is what’s putting me off! It’s basically a certainty to snap some/all of them depending on condition and then I have a jig which is pretty essential if you’re not familiar with them. On the one hand part of me says it’s drilling twelve bolts get on with it, the other part says go to work instead, earn the money in that time I’d spend doing it and let someone else have the absolute displeasure of doing them!!
 
  
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jond58
Monza


Joined: 19 Jun 2017
Posts: 195



PostPosted: Thu Aug 22, 2019 9:26 pm    Post subject: Reply with quote

You know it’s a bad job when you discuss it with your Indy as I did at the beginning of the year and you can visibly see the colour draining from their face!!!
 
  
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Rosselder83
Newbie


Joined: 01 Apr 2019
Posts: 44



PostPosted: Thu Aug 22, 2019 10:58 pm    Post subject: Reply with quote

I’m about to undertake said job, I’ve managed to remove 3 studs from one side successfully. One has snapped so far. The rest are so corroded the stud extractor can’t grip them so I think I’m going down the welding a nut on route unless anyone has any other wild ideas?

A storm ski jig is next on my list of stuff to buy
 
  
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