Exhaust back box seam repair

[APB]

I own a 2002 2.7 986 which I bought in 2014. It has done 107000 miles and came with an incomplete service history. I had a major service by Revolution Porsche about a year after purchase who also replaced the coil packs and a couple of corroded brake pipes.  Since then, I have maintained the car myself and only really undertaken regular oil changes.  I have done approximately 10,000 miles in almost 10 years, so the car is used infrequently and only covered a few hundred miles in the last couple of years. The only additional service items have been a new ignition switch and water pump and front coil spring, so my maintenance costs have been quite minimal.

I have now finally retired and now want to use the car more and undertake the more substantial work that is required which I have been putting off whilst working. The car is seal grey, and the body work is excellent, and the alloys unmarked. It had a new hood with glass screen just before I purchased. The car has been garaged whilst in my ownership and I am only the third owner. The car has just over month left on the current mot and my intention is to SORN her and get a new mot in the spring when I will start the further restoration work. A couple of the tyres are cracked which has been mentioned as an advisory in the last couple of mots, so I will be buying a complete new set. The suspension is quite tired and needs to be refurbished and the rear brakes are corroded so will be replaced. I don’t think the IMS bearing has been replaced but the clutch is good and light, so I suspect that it has at some point. I don’t intend doing the IMS due to the milage and on the basis that if hasn’t gone yet it should be good. I have never seen evidence of metal when I have dissected the filter at oil changes.

My real query relates to the exhaust. The seam on the back box is split in places and has been like that for several years. I would not want to replace with a cheap noisy drone box so would be looking at a Dansk which are over £1200. Whilst some of the work I would tackle myself I am sure the existing box would be difficult to remove so I would need to leave this job to my local Indy. I anticipate the cost would be in the region of £1500 -£2000 which is more than the valuation WBAC have placed on the car! I suspect the back box will start to leak soon and if so, I assume this is an mot failure. Can a temporary repair be achieved using gum gum to get though an mot? I would be interested to know if this has been done by others. I do intend to replace the exhaust system, but I am trying to sort out a priority list in my mind and if the car were to fail on an exhaust leak it becomes more of a logistical challenge getting it replaced.

 

[Nobbie]

I think it would only fail if there were an appreciable escape of exhaust gases. They’re not that hard to remove once you’ve got the bumper off which is pretty straightforward. If you took it off at home you could take it to a welder and see if they could patch it up to keep it going for a couple of years.

For the sake of £50, you could get it MOT’d now and if it fails at least you know what work you’ve got to do while it’s off the road.

[Mike1960]

I agree that the exhaust is easy to remove, IF, the manifold bolts can be removed. You should be able to see if they are looking bad once the rear wheels are off.

Not sure about 986, but you can get decent used stock exhausts for 987.2 fairly cheap. Lots of people change them out for more vocal types. I got one a couple of years ago off eBay, complete with tail pipe, from a vehicle that had only done 40K miles for £40. So possibly worth keeping your eyes open used ones.

Exhausts can be TIG welded by a good welder. The seems should have enough metal that they won’t blow through when welded.

Good luck with your projects. 

Edited November 10, 2023 by Mike1960

[Nobbie]

30 minutes ago, Mike1960 said:

I agree that the exhaust is easy to remove, IF, the manifold bolts can be removed. You should be able to see if they are looking bad once the rear wheels are off.

Not sure about 986, but you can get decent used stock exhausts for 987.2 fairly cheap. Lots of people change them out for more vocal types. I got one a couple of years ago off eBay, complete with tail pipe, from a vehicle that had only done 40K miles for £40. So possibly worth keeping your eyes open used ones.

Exhausts can be TIG welded by a good welder. The seems should have enough metal that they won’t blow through when welded.

Good luck with your projects. 

No need to remove manifold to get the back box off, just remove the clamps either side and unbolt the bracket supporting the back box.

[½cwt]

The seam on the back box on my 2000 car looks terrible but it is still gas tight.

[PaulQ]

I used a hi temp epoxy on mine. Scotchweld DP760

[½cwt]

39 minutes ago, PaulQ said:

I used a hi temp epoxy on mine. Scotchweld DP760

Got to be worth a punt for about £40, I see in the spec it is good to 230°C.

[Boxstercol]

Alternatively get a new stainless backbox fabricated at a custom exhaust place - they can ‘tune’ them to be as loud / quiet as you want - just ask that they fabricate a new one with stock sound, can’t see that being more than £500.