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Stainless exhaust bolts and fittings, advice or link pls.

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
 
deMort said:
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:

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:
 
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:

 
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 .
 
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 :thumbs:
 
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!!
 
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!!!
 
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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