Leaky exhaust, trying to sort through options

300D · Oct 20, 2019

2003 Wagon MT has a leaky exhaust. A preliminary inspection shows it leaking at the rear seam of the catalytic converter, mid-pipe clamp, and back of exhaust. Not too much rust really, except for the mid-pipe, which makes me thing it is a replacement.

I want the quietest, highest MPG, and most environmentally friendly system that will last. Price is of a concern.

So many different options it makes my head spin.

Cat-back won't fix the leaky cat, right?
Turbo-back includes the downpipe, which has the cat welded in? Possible to just get the cat repaired, and then do a cat-back system?

Being in Maine, and parking it on a gravel driveway, high grade stainless should be my choice, correct?

What's the consensus on Hottexhaust.com? They look like they have great prices on stainless systems. Currently a sale, and a complete turbo back system looks like it is $500. But the muffler looks like a cigar rather than a full contraption.

Magnaflow has a decent looking downpipe with cat. Anyone with experience with these?

I am not afraid of 2.5", but don't want this car to be loud on the highway. I drive mostly highway at 75mph.

Thoughts?
Thanks.

300D · Oct 20, 2019

This is the magnaflow downpipe with catalytic converter:
https://www.magnaflow.com/products/...t-direct-fit-catalytic-converter?aces=9008890

Available at a ton of places. Anyone with experience?

300D · Oct 20, 2019

This is the HottExhaust full 2.5" system: https://www.hottexhaust.com/Hottexhaust_10250tdi

$500 on sale.

300D · Oct 21, 2019

And the Buzzken 2.5": https://www.tunemyeuro.com/buzzken-...5-golf-jetta-jsw-new-beetle-2-5-downpipe-kit/ Which is $960 shipped.
Seems like the HottExhaust.com I posted originally doesn't get the best reviews. I love buying my parts from IDParts, but it seems like either it is aluminized for a great price, or very excellent looking stainless for $1400 for downpipe, cat, and muffler.
I am hoping people can weigh in with their own experiences in terms of rust, noise, ease of installation, etc. I know there are a ton of posts about exhaust, but they are all from 3+ years ago and generally focus on performance.

flee · Oct 21, 2019

You will not be disappointed with the BuzzKen fit, quality or function.
I recommend getting an extra resonator (or two) if added noise is a concern, too.

300D · Oct 21, 2019

The back seam of the cat:

The clamp that looks like maybe it is just the clamp that is shot:

The muffler:

I am thinking a new clamp, plus a visit to an exhaust shop to fix the cat seam? Does that look like something that can be fixed on car? Rest of downpipe looks decent. Muffler is shot for sure.

Powder Hound · Oct 21, 2019

Muffler is a replacement, clamp is there because of the rear part with the muffler being replaced - that's where the cut goes. And yeah, just buy a new clamp. But you could get just the muffler part and a clamp as well.

The cat can be welded - you'd need someone who is pretty good and is patient. Nobody's aftermarket cat will last more than a few weeks, so may as well keep the OEM as long as possible. Check the flex joint. If that starts leaking, you will smell it in the cabin as the noise gets quite loud.

Buying stainless is a little tricky. 304 is what you really want, but the price goes up a lot. 409 is what automakers use, and it is a cheap grade that obviously rusts a lot. Probably not as much as gassers do since it doesn't get so hot on a diesel, but nevertheless, I think it is the cheapest grade they can still dare to call "stainless".

I wonder if aluminized would have reasonable longevity if a sufficient exhaust type high temp paint was applied. Anybody ever try that?

Cheers,

PH

intro · Oct 21, 2019

300D said:
The back seam of the cat:

The clamp that looks like maybe it is just the clamp that is shot:

The muffler:

I am thinking a new clamp, plus a visit to an exhaust shop to fix the cat seam? Does that look like something that can be fixed on car? Rest of downpipe looks decent. Muffler is shot for sure.

I don't think that can be welded. You can't weld rust.

300D · Oct 23, 2019

intro said:
I don't think that can be welded. You can't weld rust.

To me it looks like the back of the cat has a poor original weld and is not actually that rusty. That's what I am hoping anyway.

300D · Oct 23, 2019

Powder Hound said:
Muffler is a replacement, clamp is there because of the rear part with the muffler being replaced - that's where the cut goes. And yeah, just buy a new clamp. But you could get just the muffler part and a clamp as well.

The cat can be welded - you'd need someone who is pretty good and is patient. Nobody's aftermarket cat will last more than a few weeks, so may as well keep the OEM as long as possible. Check the flex joint. If that starts leaking, you will smell it in the cabin as the noise gets quite loud.

Buying stainless is a little tricky. 304 is what you really want, but the price goes up a lot. 409 is what automakers use, and it is a cheap grade that obviously rusts a lot. Probably not as much as gassers do since it doesn't get so hot on a diesel, but nevertheless, I think it is the cheapest grade they can still dare to call "stainless".

I wonder if aluminized would have reasonable longevity if a sufficient exhaust type high temp paint was applied. Anybody ever try that?

Cheers,

PH

Is the check for the flex joint just listening and sniffing from in the cabin? Or will there be visible signs? I have looked at it pretty carefully and don't see anything in particular.

Do these cats go bad? I have searched a ton and there is so much conflicting information. Since I have owned it the exhaust is down right diesel stinky. I want the car to be as correct in terms of emissions that it can be. OEM cat is a pretty penny.

oilhammer · Oct 23, 2019

You need a new catalyst/downpipe assembly. Someone has already tried to weld on it. It was temporary. It's done. You cannot weld rust.

Nothing will fit like the original, but Bosal has a decent stock replacement that fits reasonably well and is not terribly expensive, and retains a proper catalyst. They will also have the rest of the system (which you also obviously need) all the way back out.

300D · Oct 23, 2019

oilhammer said:
You need a new catalyst/downpipe assembly. Someone has already tried to weld on it. It was temporary. It's done. You cannot weld rust.
Nothing will fit like the original, but Bosal has a decent stock replacement that fits reasonably well and is not terribly expensive, and retains a proper catalyst. They will also have the rest of the system (which you also obviously need) all the way back out.

Any experience with the Bosal system in terms of rust? IDParts has the complete turbo back Bosal for under $500. They responded that it will last as long as OE exhaust. I don't know what that means in terms of Maine. Perhaps a year? Which I say only half jokingly...

(One commute last winter from the coast to Augusta I was behind a plow that was salting the roads. I was picturing my car not making it to Augusta and just melting into the road right then and there...)

oilhammer · Oct 23, 2019

Probably as good as the original, and in your area, that may not be all that long. Your car already has had the catalyst welded on, and the muffler/pipe replaced further back (as evidenced by the sleeve clamp, the original is all one piece, the replacements are two piece).

300D · Oct 23, 2019

oilhammer said:
Probably as good as the original, and in your area, that may not be all that long. Your car already has had the catalyst welded on, and the muffler/pipe replaced further back (as evidenced by the sleeve clamp, the original is all one piece, the replacements are two piece).

I am thinking the downpipe and cat are maybe original as the front of the cat looks like a factory weld:

But the rest looks replaced.

Powder Hound · Oct 23, 2019

You can tell by the exhaust smell whether the catalyst is working or not. I remember that my original catalyst produced exhaust that smelled like a paraffin candle when it was new. Later, not so much.

What happens to catalysts is that anything untoward (strange metals like lead, or non-hydrocarbon atoms like sulfur) will combine on a permanent basis with the precious metals of the catalyst to keep them from working. The process is called poisoning the catalyst. So the precious metals (platinum, palladium) are still there, but they aren't working anymore.

Fortunately for the ALH generation of engine, the emissions controls don't include a tattletale secondary (or first, for that matter) O2 sensor that tells how 'efficient' the catalyst is. So if it is poisoned, the OBDII won't care, and unless your state has an exhaust sniffer, it probably won't be able to tell. In a healthy diesel, the only bad exhaust gas that exists higher than the arbitrary EPA limits is NOx anyway.

And in answer to the above question, the flex joint if going bad displays the same way as any other part where there is a leak: there is the tell-tale carbon/soot display along with the outer braid probably looking like it has had a troubled life in that spot. It will sound louder, and you might smell it in the cabin.

The above comments are correct: you can't weld rust. It won't combine with any kind of welding to produce a decent weld, even if you could get it to stick around. And any electric type welding will be difficult as rust does not conduct electricity. Hence, if you try and weld a rusty break, you'll have to clean the rust, and then carefully fill in around the hole until you close it up. Lots of welders that don't have a delicate touch end up merely expanding the hole.

Cheers,

PH

300D · Oct 25, 2019

Powder Hound said:
You can tell by the exhaust smell whether the catalyst is working or not. I remember that my original catalyst produced exhaust that smelled like a paraffin candle when it was new. Later, not so much.

What happens to catalysts is that anything untoward (strange metals like lead, or non-hydrocarbon atoms like sulfur) will combine on a permanent basis with the precious metals of the catalyst to keep them from working. The process is called poisoning the catalyst. So the precious metals (platinum, palladium) are still there, but they aren't working anymore.

Fortunately for the ALH generation of engine, the emissions controls don't include a tattletale secondary (or first, for that matter) O2 sensor that tells how 'efficient' the catalyst is. So if it is poisoned, the OBDII won't care, and unless your state has an exhaust sniffer, it probably won't be able to tell. In a healthy diesel, the only bad exhaust gas that exists higher than the arbitrary EPA limits is NOx anyway.

And in answer to the above question, the flex joint if going bad displays the same way as any other part where there is a leak: there is the tell-tale carbon/soot display along with the outer braid probably looking like it has had a troubled life in that spot. It will sound louder, and you might smell it in the cabin.

The above comments are correct: you can't weld rust. It won't combine with any kind of welding to produce a decent weld, even if you could get it to stick around. And any electric type welding will be difficult as rust does not conduct electricity. Hence, if you try and weld a rusty break, you'll have to clean the rust, and then carefully fill in around the hole until you close it up. Lots of welders that don't have a delicate touch end up merely expanding the hole.

Cheers,

PH

PH,

Great info about the exhaust smell and such. Makes a lot of sense. After continually digging for prices and sorting materials and sized and everything, right now leaning toward the Buzzken as it actually holds a lot of value. 409 stainless front to back, cat and muffler. $960 shipped. I imagine it will be good for 10 years. The IDParts looks really nice and is 304 stainless, but about $500 more. The aluminized steel from Bosal has gone up in price and is now around $540, but I imagine I would only get about 3-5 years from aluminized under my environment situation.

I also dug into the Magnaflow stainless direct fit dowpipe with cat. 409 stainless, stock size, and about $365. Not a bad deal, but if I need to stick something behind it that is similar quality, I wouldn't end up with any savings.

Kind of odd that in my search for decent quality longer lasting, it leads me to a performance exhaust. But I guess that makes sense with an older car. No one puts the time into fabricating something nice just to bring it back to stock.

Much thanks for all the responses.

flee · Oct 25, 2019

Add at least one resonator to the BuzzKen pipe order.
They don't cost much. His muffler isn't as quiet as the factory one.
You will be glad you did.

turbocharged798 · Oct 26, 2019

In my experience, nothing fits like an OEM downpipe. I find all the aftermarket downpipes just plain suck. Either flex pipe is too short, hangers are in wrong locations, or something is just off. Its a complex piece that requires a lot of accuracy and engineering.

That downpipe is 100 percent fixable. VW for some odd reason used mild steel for the pipe between the cat and rear mid section. As a result, they always rot out right after the cat. I fix them with a piece of 2 in 409 stainless pipe. The rest of the downpipe is 409 stainless and will never rust out. Also a great time to inspect and replace the flex pipe as well.

Deadend · Oct 29, 2019

What good fortune!

I'm very much considering an exhaust refresh on the '01 Jetta. The flex pipe is is very poor shape (It's been replaced once 8 years ago), the muffler hanger has fallen off, and the cat.. hasn't been there for 8 years (No emissions testing in 'Berta!).

Anyways I'm going to go full turbo-back. This looks like a pretty cost effective solution.

https://mufflerexpress.ca/products/...-catalytic-converter-alh?variant=896701661194

But what I really want to know from the community is: when it comes to fitting the pipes together, weld or clamp? I'd really prefer not to ever have to tighten up clamps, but I'm only mildly confident in my MIG welding skills, which is all I've ever done.

300D · Oct 29, 2019

Deadend said:
What good fortune!

I'm very much considering an exhaust refresh on the '01 Jetta. The flex pipe is is very poor shape (It's been replaced once 8 years ago), the muffler hanger has fallen off, and the cat.. hasn't been there for 8 years (No emissions testing in 'Berta!).

Anyways I'm going to go full turbo-back. This looks like a pretty cost effective solution.

https://mufflerexpress.ca/products/...-catalytic-converter-alh?variant=896701661194

But what I really want to know from the community is: when it comes to fitting the pipes together, weld or clamp? I'd really prefer not to ever have to tighten up clamps, but I'm only mildly confident in my MIG welding skills, which is all I've ever done.

Good looking price, but that low means aluminized steel, and if you are in rust country, that means a short life. Original downpipe in front of the cat is 409 stainless or something close, which is why they have lasted this long.

300D · Oct 29, 2019

Wait. Just saw that that link is to three different downpipes. Built differently for different warranty periods. Interesting. 2 year warranty option gets you ‘generally stainless tubing’. I imagine this is 409. But then the price is not too far off Buzzken pricing.

Deadend · Oct 29, 2019

300D said:
Good looking price, but that low means aluminized steel, and if you are in rust country, that means a short life. Original downpipe in front of the cat is 409 stainless or something close, which is why they have lasted this long.

Well it does *say* it's stainless, so I suppose I should be able to return it if not as advertised. Honestly, I'm not too concerned about it lasting more then 2-3 years, doubt the car is going to be on the road that much longer. And like I said, the original one *didn't* last this long, it's already been butchered by a muffler shop that chopped that cat and welded in a new flex (and did a piss job at it for a top dollar at that). But good catch on the warranty descriptions, I should probably get at least the 1 year which does mention 409.

What I'm really curious about is, weather or not to trust those exhaust clamps, or to get it welded (or attempt to weld it myself).

flee · Oct 30, 2019

I don't recommend MIG welding stainless unless you use stainless wire.
Even if you get it to seal the weld will be of poor quality and corrode rapidly.
If the clamps are good they should last.

Leaky exhaust, trying to sort through options

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