Blowing exhaust

[Drew20]

Dropped the exhaust today; the winter project is to fix the blow (MOT failure) and tidy it all up. As you can see, the front silencer and the small mid box have both been deleted and it now has a straight pipe to the large rear silencer. As you can also see the whole system except the rear silencer is rust coloured!! This is surface rust only, and doesn't cause me concern, except when I can see it.

Of more concern to me is the blow coming from the joint between the modified downpipe and the straight pipe to the rear. This has been caused by a distortion of the joint by the seal clamp.

Questions: to fix the blow I plan to clean the surfaces, return the pipe to a true circle and rebuild the joint and clamp such that the clamp bolt aligns to the pipe's 'slot' (the slot cut in the pipe to allow for shrinkage as the clamp tightens). Thoughts?
To tidy it all up I had planned to take the surface rust off with a wire wheel, and then paint with high temp paint. But now I'm not so sure. Most of the exhaust is invisible except when the car is on ramps. Sure, it's embarrassing when on ramps, but the clean and original floor pan makes up for this I think!! So perhaps I should leave as is, in the vague hope that the surface rust is protecting the good steel somehow??
The bit of the exhaust that this won't work for is the tailpipe, as this is visible at all times, and I want it tidy. So should I just take the rust off and polish it up a bit, or would paint also help here, I'm not sure?

Thoughts and suggestions welcome

 

[tferrer]

This must sound quite a bit different. How loud is it?

 

[Drew20]

Just about perfect....in my opinion!! (You can't hear the rust)

Though the noise levels have been commented on, a nice straight six raspy howl above 3500pm, best driven with the rear windows open, for full effect

 

[Honolulu]

1. Rust doesn't protect anything.
2. I'd use a wire wheel or cup brush to remove rust, then apply a rust converter product (phosphoric acid compound) which will turn the remaining red-brown rust a nice dull black, then roughly scrub with water and dry it off. I like brushable "Ospho" and have several old bottles of pasty "Extend" brands as well. It's difficult to find a paint product that is as heat resistant as the labels suggest. VHT brand makes promises but I can't/won't back them up. Some like to have their exhausts ceramic coated and those expensive treatments are supposed to be quite durable. If the sections aft of the collector, it might be cool enough for some inexpensive rattle cans to survive.

Your semi-straight exhaust tempts me to try something similar. I was house-hunting with my young wife and my Dad in my wife's Bavaria, when the exhaust separated at the aft collector joint. Short straight pipes... loud as hell. My wife was mortified and tried to hide, my Dad thought it was hilarious. I of course tended to agree with the funny parts... it's a guy thing.

 

[eriknetherlands]

Unfortunately the way to preserve it requires some elbow grease. Indeed keeping the rust doesn't help. (It wouldn't have gotten so bad of it did, didn't it? )
Taking the rust out is not different with a muffler compared to a body; remove & seal is the only way.

 

[Drew20]

Here's the tailpipe after a wire wheel, a bit of coarse grade wet and dry and a scrub up in soapy water. Next is a wrap with some rust converter paste, then some paint to finish I think. What colour paint do you think, options appear to be black (matt, satin or gloss), silver or graphite. Leaning towards graphite myself, as painted silver never looks "right".
Only the end of the tailpipe is ever visible, the bit that sticks out beyond the rear wing that's not covered by the chrome tip trim.

Once I get the tailpipe sorted I'll move on to the straight section, much longer = more elbow grease required, but my labour costs are very low

 

[eriknetherlands]

Hi, i had a NOS small center damper and first (merging) damper, both original Eberspacher, they both had a dull light grey paint.

 

[stphers]

VHT high heat gray primer!!

 

[Stevehose]

POR-15 makes grey and silver high temp paint which hold up very well, even on manifolds

 

[Drew20]

Well I might need a plan B. Discovered a large hole in a weld in the straight section, an so am leaning towards replacing the system rather than throw more time and money at a system which has clearly seen better days, and has been chopped about a bit.
Think my options are W&N, fritzbits, or bmw/eberspacher (OEM). Price wise I think all 3 options are probably similar, but the OEM system might be hard to track down. My rear silencer looks in v good condition though, clearly not as old as the rest of the system.
As the UK has now left the EU building, W&N no longer charge German VAT, but I assume I'd need to pay uk VAT on import, plus import duties maybe??

Or I could just bodge the existing exhaust for the time being. Clearly not a long term option, or even a mid term option probably, but gives me more time to look at options.

 

[E9madada]

Might be worth a look.

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[Drew20]

Thanks, have dropped him a note. Not too far from me as it happens. He tells me he has welded the silencers together, seems a bit odd/ drastic!!

 

[HB Chris]

Welded is factory I think, there are no slip joints and clamps.

 

[Drew20]

Ah ok, mine has a u-clamp join where the long straight meets the rear box. All the other joins are missing, clearly!
Cheers for the info

 

[deQuincey]

Thanks, have dropped him a note. Not too far from me as it happens. He tells me he has welded the silencers together, seems a bit odd/ drastic!!

yes you have to weld them when you install them