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Stainless exhaust bolts and fittings, advice or link pls.

Is this uniquely a Porsche problem? What do other manufacturers do, such as McLaren or Ferrari for instance? Or in aerospace?

It certainly seems to me that Porsche have "gone cheap" in all the nuts and bolts around the exhaust, and replacing them is beyond the skills of the average DIY'er - or at least in Martin's case it drives us, err, nuts.
 
I've just had my manifolds replaced and the mounting bolts replaced with Popopbangbang's titanium studs (And non-titanium K-Nuts). I'm no metalurgist and fully accept that this solution is very expensive and probably a wildly over the top solution but you know what? I don't care. The many (And detailed) explanations PPBB provided impressed me and every time I look under the car I see those sparkling bits of jewellery (Be under no illusion, the studs are a work of art!) I get a small warm an' fuzzy feeling.

A point also worth noting is that I had the work done at Brookspeed in Eastleigh, Hampshire and 10 out of the 12 studs sheared. Luckily Brookspeed have a local guy with the engineering kit to drill them out (Far better than me with a cordless B&Q drill and a dedicated drill guide). Suffice to say I would rather not go through that again (Though truth be told the drilling out work was less that I had expected). It wasn't cheap but damn I'm glad I didn't try and do it myself.

So that's my story. Is the expense justified? Probably not, but for myself I'm glad that is now in the category of "A good job well done". You can also be certain that if I ever decide to sell the car (HIGHLY unlikely!) I'll be sure to tell and show the new owner the glorious Titanium studs shining away under the engine.
 
Counter Of Beans said:
Is this uniquely a Porsche problem? What do other manufacturers do, such as McLaren or Ferrari for instance? Or in aerospace?

It certainly seems to me that Porsche have "gone cheap" in all the nuts and bolts around the exhaust, and replacing them is beyond the skills of the average DIY'er - or at least in Martin's case it drives us, err, nuts.

I part-own an aeroplane and it has a flat four six litre engine with Ali heads. as it's an American aeroplane we use aircraft quality AN fasteners throughout. The exhaust manifold studs are plain steel AN, which is cadmium plated rather than zinc plated like the Porsche fasteners. Cadmium provides better corrosion resistance, but they still rust and require replacement every few years. As for the strength of the studs, they are 116,000 psi, which is there or thereabouts the Porsche ones, and about 15-20% stronger than stainless ones.

If anyone reading this has their heart set on using mild steel studs, then cadmium plated ones are the way to go, but ultimately, stainless, Ti, or inconel are the only practical way to ensure the studs aren't a service item. Also, aircraft grade fasteners are so pricey that you would be spending less on stainless and not much more if you went for Ti.

In essence, yes, Porsche went cheap and specced fasteners all over the car to a price without any regard to future serviceability. As owners it's down to us to replace those fasteners with something that will still function in five years time. I'm sure Demort of this parish will back me up when I say that even cars as recent as the 997.2 now have this problem, so it's not like it was just a bean counter having his way with early 996s.
 
Martin996RSR said:
I'm sure Demort of this parish will back me up when I say that even cars as recent as the 997.2 now have this problem, so it's not like it was just a bean counter having his way with early 996s.

Consider yourself backed up young man :D

Rule of thumb .. the newer the car the faster the exhaust ( mainly flange ) studs nuts corrode and let go .

i've seen almost nothing left of a 993 exhaust bolt but it was original and still holding firm .. although to be fair i think the two halves of the exhaust had rusted together and would never come apart !

986 early version .. i did one today .. 130k miles and original studs .. not blowing but so close we had to replace .

I've already replaced 991 / 981 flange studs with 997 being very common .

Chocolate springs to mind .

To be fair .. well a little bit .. we have pretty awful weather and we salt our roads .. we also have a lot of coast line , salt air ..

All of these have a huge impact on not just the exhaust bolts ...

You would have thought that our market would have more protection due to this .. after all .. even the Romans hated our weather so it's not exactly a new thing .
 
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
 
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.
 
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:
 
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!
 
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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crash7 said:
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?
 
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!!
 
Paynewright said:
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 :D

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 .. :oops:

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/
 
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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