For those of you who replaced your rusty exhaust flange studs... - 986 Forum - The Community for Porsche Boxster & Cayman Owners

dachrist · 12-10-2018, 02:54 PM

...how did you deal with the welded on nut that is attached to the exhaust header side?

When removing the exhaust for my IMS replacement job, I snapped off all the nuts on the exhaust flange to header connection. I was able to remove the one bolt that goes through the welded nut (the one that is on top of the triangle). I want to replace everything with new SS hardware, but not sure how to deal with that welded on nut? Air hammer? Dremel? Just want some ideas of what worked or not worked.

NewArt · 12-10-2018, 03:37 PM

You can just reuse it. It's not like you change these things every week. Well, I suppose that if you did, things wouldn't get seized, but that's another story. Or you can easily drill it out with a decent drill bit (cobalt works well) and put the ss nut on afterwards. Or you can use a Dremel multi-tool with a carbide blade to saw it off.

maytag · 12-10-2018, 04:20 PM

I used a fire-saw.

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Dave80GTSi · 12-10-2018, 04:45 PM

Easy.

Use a Dremel cut-off disc and slice thru the tack welds which were used to secure the top nut to the front side of the flange. Once the welds are cut, the nut will literally fall off.

Replace with a conventional nut and bolt, the same style as the other pair of flange fasteners.

dachrist · 12-12-2018, 06:49 AM

Thanks for the suggestions guys. I can't re-use the nut, it is really rusted up in there so I do need to get it off. I will try the dremel cut off disc and see how it goes. The only issue I may have is access in there, its pretty tight...

NewArt · 12-12-2018, 09:15 AM

Quote:

Originally Posted by dachrist

Thanks for the suggestions guys. I can't re-use the nut, it is really rusted up in there so I do need to get it off. I will try the dremel cut off disc and see how it goes. The only issue I may have is access in there, its pretty tight...

If you have access to a Dremel (or other) multi-tool, it requires less space using a carbide blade.

Dave80GTSi · 12-12-2018, 03:37 PM

I am puzzled.

If the bolt which goes thru the welded top nut is already out, then why do you need to remove this rusty nut now?

Why not simply run a tap thru this old nut, thus recutting the threads, and then just use a new bolt?

Traco · 12-12-2018, 11:39 PM

I replaced all 6 last spring but mine is a Euro car so. It sure if it’s different.

On the OEM set up the bolts are actually splined studs press for into the cat side of the flange and the nuts are on the header side.

If something has been welded it sounds like someone has carried out some sort of quick fix at some stage as opposed to doing it the right and hard way.

I had to cut, grind, air hammer and use a press to complete the job.

Few pics for ref if it helps.

Detailed thread on Porsche club ireland forum below. The IT guys have been upgrading the hosting so I guess that’s why the IP address is there and not the regular URL but google should find it in the Boxster section of Porsche Ckub Ireland Forum

http://173.249.44.54/forum/index.php?topic=8501.0

This years job is to replace the ones attaching headers to the block - fun times ahead.

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particlewave · 12-13-2018, 12:21 AM

Quote:

Originally Posted by Traco

If something has been welded it sounds like someone has carried out some sort of quick fix at some stage as opposed to doing it the right and hard way.

Incorrect. One of the nuts is captive and it's carrier is welded to the flange.

Quote:

Originally Posted by Dave80GTSi

I am puzzled.

If the bolt which goes thru the welded top nut is already out, then why do you need to remove this rusty nut now?

Why not simply run a tap thru this old nut, thus recutting the threads, and then just use a new bolt?

Because it takes only a few seconds to cut it off and you don't want to reuse a rusted fastener, new threads or not. It will quickly rust again.

Traco · 12-13-2018, 05:51 AM

Quote:

Originally Posted by particlewave

Incorrect. One of the nuts is captive and it's carrier is welded to the flange.

Are you saying a nut like this in the pic below?

If so then how do you screw a splined stud into that? This is the 6 splined studs that I took out of mine and there was no evidence of any captive nut on the header flange?

These had to be pressed out with a vice after a lot of heat.

As I said in my first post mine is a Euro S and the US has a different exhaust layout so maybe it’s different but I know what I took apart.

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dachrist · 12-13-2018, 07:07 AM

Quote:

Originally Posted by NewArt

If you have access to a Dremel (or other) multi-tool, it requires less space using a carbide blade.

Unfortunately I only have the old school Dremel rotary tool. I will give it a shot, if it doesn't work I will look at getting a multi-tool. Hmmm....Christmas is right around the corner....

dachrist · 12-13-2018, 07:09 AM

Quote:

Originally Posted by Dave80GTSi

I am puzzled.

If the bolt which goes thru the welded top nut is already out, then why do you need to remove this rusty nut now?

Why not simply run a tap thru this old nut, thus recutting the threads, and then just use a new bolt?

I want to replace everything with SS hardware so the old nut has to go.

particlewave · 12-13-2018, 08:15 AM

Quote:

Originally Posted by Traco

Are you saying a nut like this in the pic below?

If so then how do you screw a splined stud into that? This is the 6 splined studs that I took out of mine and there was no evidence of any captive nut on the header

Yes, similar to that. It's been a while since I had mine off, but I believe two bolts on each side were splined studs and the third was a standard bolt with captive nut. A real PITA.

I replaced all of mine with SS bolts and nuts.

dachrist · 12-13-2018, 08:45 AM

Mine appears to just be a nut that is tack welded in 3 spots to the exhaust flange.

particlewave · 12-13-2018, 08:52 AM

Mine was definitely a captive nut with the nut loose inside the carrier. I guess the exhaust fasteners were an evolving experiment

dachrist · 12-13-2018, 09:13 AM

What year was yours on? Mine is a 2004.

particlewave · 12-13-2018, 09:51 AM

Quote:

Originally Posted by dachrist

what year was yours on? Mine is a 2004.

'99.

......

particlewave · 12-13-2018, 03:41 PM

It looks like it's just the earlier models and may just be on one side.

Photos pulled from different sources showing the captive nut with carrier/cage welded to the flange:

maytag · 12-13-2018, 05:43 PM

I did mine just a few months ago. Mine is an '03 S (US version).
There were NO studs, splined or otherwise. All 6 were bolts with nuts. At least one of the nuts on each side was "captive", meaning it was welded to the flange. It was NOT in a carrier of any sort. I say at least one on each side because as bad as the rust situation was, I didn't bother trying to un-thread anything: I got the torch out and simply cut them all off the back of the flange.

It sounds like the fasteners at this location must've been a changing item.