Exhaust Silencer Removal

dc2100k · 13 Nov 2019

Hi All, I'm part way through stripping down the back of my car and was wondering if anyone had any tips for the following tasks:

1. removing the smaller 70mm nut&bolt that holds the silencer to the bracket. these have rusted away to a little point but are still holding firm. I have removed the exhaust tips and cat clamps, plus the 125mm nuts but I can't get anything in the gap between silencer and manifold to remove this smaller rearmost nut. Any advice gratefully received!!

2. Heatshield fixings. Quite a few of my various heatshield fixings have broken as a result of some bi-metallic corrosion with the steel screw and I was wondering if there is a type of washer that would suit to reaffix these with the original screws.

3. Exhaust paste: is this required when reassembling the cat clamps and exhaust tips?

Cheers.

fot0 · 13 Nov 2019

Done this twice. On both occasions I used an angle grinder on the clamps. Unless there is any thread left on bolts, then you might be lucky with wd40 and a wire brush. Otherwise use an impact socket. When I remove mufflers I tend to undo the 3 bolts inside the cradle/hanger.

I would advice using OEM clamps. I bought a set off a well known supplier and basically were made of the cheap metal and they went in the skip.

For the heat shield, aluminium/zinc washers will help and move contact area.

I used a sealant on the cat/muffler sleeve only.

dc2100k · 13 Nov 2019

Thanks foto. I have already angle ground the cat/muffler clamps off as there wasn't much in the way of bolts left on them! The three bolts that attach the silencer bracket to the cradle are solid but I don't think they will easily undo so I was planning on leaving them in place and unbolting the silencer from the bracket. I just can't find anything small enough to fit through the gap that will let me nip the bottom off the 70mm bolt to remove it. Maybe a bit of heat might do it?

I have a full replacement set of brackets, clamps and bolts from Type911 here that I was going to use. Are these the ones that are only fit for the bin???

Good thinking on the washers, the rest of the heat shields are in good shape.

jezgreen911 · 13 Nov 2019

On both occasions that I've removed my exhaust I to have removed the three nuts that hold the bracket to the hanger cradle, If I remember correctly the muffler to bracket bolts go in from the top so there wouldn't be room to get them out to remove the muffler with the bracket left in situ :?: :dont know:

I have a pair of new genuine Porsche cat/muffler clamps to sell as they are now surplus to requirements if you decide against the Type911 or Topgear sleeve clamps

Hughb · 13 Nov 2019

I am gonna need to do this on my 2003 C2 in the not too distant future and have researched it extensively.

I can foresee 'world of pain' coming down the line on both the vertical muffler bolts and/or three nuts on each cradle/hanger bracket.

Take a look at this YouTube video to see what can be done with the right equipment....... it's awesome.

https://youtu.be/7uqf4LEKRIQ

My inclination is to go for these three nuts, but mine don't look like nuts anymore .... probably with oxy cutting torch, trying not to destroy the bracket in the process!

Or plan B: Take a look at PCW Exhaust Mods on the internet, I have just asked him for a price to remove/'bottom seam weld' my mufflers and fix all these corroded nuts/ studs, including the cat/manifold clamp bolts.

This 'virtually universal' corrosion problem has been annoying me ever since owning the car and I will be happier when it's fixed.

Then I will be left with just the 'Big One', the 2 x 6 manifold bolts ......

dc2100k · 14 Nov 2019

Hi Hugh, I wouldn't describe it as a world of pain, it's oddly cathartic working through all the fixings! It took longer to get the bumper and heatshields off tbh!

That video is very descriptive but I'm not sure why they took the 70mm nut off with the cutting torch, looks like a ratchet would have taken it straight off? I don't want to get into the business of welding new studs on so I'm going to try and get the silencer off the vertical bracket first. I can see the advantage of putting the 70/125 fixings in from the top so if the bolts fall off then the silencer cannot easily demount itself, but in this video they put it back in from the bottom even though the bracket is off the car?!? I think with threadlock and properly torqued it should be fine this way in any case.

My priority is not to damage the manifold mountings or the exhaust cradles as removing the manifolds is is not on my to do list this year! Everything is off now except these two 70mm nuts and bolts, as per yours the nut doesn't really exist anymore but there's enough of a flange left to stop the bolt coming out. Btw I'm not sure if it is a sensible idea to weld up the original boxes, whilst I'm sure it will sort the bottom seam, as I've been taking these boxes off the flexi on one pretty much crumbled off so i'd say a false economy.

Dc2100k

dc2100k · 14 Nov 2019

Hi Jez, I've just had a closer look at the Type911 fixings and they seem to all intents and purposes the same as the original Porsche ones so I will use those.

Hughb · 14 Nov 2019

world of pain ... a bit OTT perhaps, (its a deMort phrase) as the carthartic aspect is, I agree, entirely relevant too!

Have a look at this video from 'MY 911' which specifically addresses the 70/125 bolts.

https://youtu.be/0u7wu3EArJo

Nevertheless sometimes we seem to spend hours doing something that could be done in minutes with the right approach/tools. 'MY911' attacks some of the bolts with a Dremel! (as he does with the manifold bolts in a later video). His approach stands in sharp contrast to the first video I mentioned .... He has had to remove bumper, heatshields and so on just to get started, whereas in the first video they are in and out in no time.

My logic with the welding is .... if I can correct the corroded bolt/nut issue then swopping out the silencers is not a big deal. Mine currently are not blowing and its only the bottom seam that is looking less than perfect. All that may change when I get them out and give the a shake, of course!

fot0 · 14 Nov 2019

If the 3 bolts don't undo then they will likely sheer anyway on the stud. The last bolt you mention I've done on the car and another out engine out. In car you should be able to get a small spanner on it, but will take an age with patience. But sounds like you have little to grip.

If they sheer, then you can replace with a normal bolt.

If you decide to take the cradle off the block then be careful on these bolts (if you have space) as aluminium mountings on the block get fragile. You will also need to unplug coil plug connectors.

There are also 2 vertical bolts on the plate/muffler. Never had success removing these, but it's another option to avoid the above.

Please read my previous reply on OEM parts.....just saying.

dc2100k · 14 Nov 2019

Thanks for that link Hugh, I will have a look just now. Maybe a dremel could be added to my list of tools...

Cheers foto - in retrospect I think I could probably have removed the original silencer/cat clamps with a bit of fiddling and reused them but they are now in bits! Anyway, the principal difference is that aftermarket ones are made of slightly thinner gauge galvanised steel instead of stainless, difference in gauge should be fine as regular steel is stronger than stainless. Anyway, the originals lasted 20-odd years (not the bolts which were regular steel!) and I'm not really concerned if these only last half that as I'll no doubt be taking the entire exhaust system apart to do manifolds, cradles and bolts long before I have any problems with these clamps. Anyways, you pays your money and takes your chances... the money saved compared to genuine exhaust clamps paid for a couple of (genuine!) deflection pulleys for more 'mission critical' functions...

Martin996RSR · 14 Nov 2019

The bolts go through steel spacer tubes that sit inside the braket. The bolts corrode and mechanically lock into these sometimes. I had to grind the nuts off the bolts and then use a lot of force to bend the braket enough to allow the bolts along with the spacers to be pulkled out from the top. I then bent the brackets back to their original position and used stainless nuts and bolts (inserted from underneath so they're easy to remove next time), and used 10mm ali tube from B&Q to make new spacer tubes. Much cheaper than oem parts and it will never seize solid again.

dc2100k · 14 Nov 2019

Good advice Martin.

A couple of hours in the garage and I have got the silencers off. In case anyone comes across this thread in future this is how I got them off - this assumes your silencers are going in the bin like mine:

Remove bumper & heatshields
Remove tail pipes and clamps
Remove cat/silencer clamps
Undo 125mm nut via conventional means (lots of Oxim Ultra), leave bolt in position
Grind off silencer exit pipe close to body (this needed a 230mm disc)
Carefully grind off bottom of 70mm bolt and nut, and cut bottom flange of silencer supports from the main body
Use channel lock to pull this cut off section away
Nip off top of 125mm bolt with grinder and use drift to push out body of bolt downwards
Grab silencer and waggle until the 70mm bolt (and sleeve) can be pulled out of the vertical bracket
Done!

This took about 1 hour each side after the bumper was off but I was going slowly and checking constantly when I was cutting. Probably quicker if the car was on a ramp but I'm on axle stands!!

Shalmaneser · 14 Nov 2019

Re. your question about exhaust paste - it is my understanding that any paste 'upstream' of the cat is an MOT fail, so be aware of that.

'Fitting paste must not be used on catalytic converters or any part fitted in front of a catalytic

converter; this includes down pipes that are fitted separate to the catalytic converter. Any fitting paste that gets into a catalytic converter will contaminate (poison) the monolith and cause it to heat

up so severely to the point where meltdown may occur'

Exhaust Silencer Removal

dc2100k

Trainee

fot0

Silverstone

dc2100k

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jezgreen911

Hockenheim

Hughb

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dc2100k

Trainee

dc2100k

Trainee

Hughb

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fot0

Silverstone

dc2100k

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Martin996RSR

Montreal

dc2100k

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Shalmaneser

Montreal

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