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1996 S124 E220 - 1985 VW T3 1.9DG Camper - 1998 BMW E36 328i Cabriolet
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Discussion Starter #1
With 3000 miles or so of trips to make in the Summer holidays, my car went in for a major service back in early July to keep it honest, and we did a little work to iron out a rough idle and tackled some other necessary replacements on my list. This included new plug wires and plugs, adjustment of the valve timing and inspection of valves (with new seals etc), a new steering damper and some other sundry parts.

It also had to have it's annual MOT (Ministry of Transport) test which is compulsory for all cars over 3 years old. It's a thorough and strict safety inspection that includes an emissions test, and it has consigned many 124's to the scrap-yard when owners who dislike maintenance bills receive a fail sheet that runs to 3 pages.

My indie did a pre-test inspection and noticed that emissions were pretty high - a new Lambda probe (O2 sensor) helped get the car through the test but it seemed that a new cat would probably be necessary for next year's. There has been a noticeable smell at idle as well for the last few months - rotten egg comes to mind, so watch (sniff) out for that as a sign of a failing converter, it was really noticeable with mine.

The car has been running really well since this work - quiet, smooth and more fuel efficient. But the cat started making it's 'death rattle' by the end of the next 500 mile journey - it was finally breaking up. For those that haven't experienced this yet, it sounds like ball-bearings shaken in a tin-can... it comes and goes and can make itself heard idling or under power. You can always hope it's just the heat shield rattling, but no such luck for me.

MB 124 cats are really expensive - around £800-900 last time I checked - so I was tempted to consider cheap alternatives having spent a lot of money already on the car this year. As it turned out, a pattern part for a third of the price turned out to be my only choice - MB can no longer sell me a catalytic converter for my car. There are none in the UK, and none left to order in Germany either.

This is a taste of things to come - owners forced to rely on the after market without the choice of OEM. Thankfully the cat I obtained fit very well and had the correct threaded mount for the sensor, but I don't expect it to last more than 3 years (it has a 2 year warranty). Anyone else found any other important parts suddenly becoming NLA? Maybe it's finally time to start hoarding parts...
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
Over here in NA there are quite a few generic alternatives for Cats, though I have no idea how efficient they are. I'm looking into buying one for my project wagon which is diesel, but I have no way to measure how well it works or whether it's even just a welded box of snake oil.
 

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1990 Mercedes Benz 300E
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1,336 Posts
parts.com still has a price listing for the OEM cat... last I looked it was in the $1600 range.
 

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1996 S124 E220 - 1985 VW T3 1.9DG Camper - 1998 BMW E36 328i Cabriolet
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662 Posts
Discussion Starter #4
Yes zeitgeist, that's a tricky one. All shops here have the machine and probe to test the exhaust emissions so I suppose a part could be bought, fitted and tested to see if it meets legal requirements and returned under warranty if not. As far as I'm concerned, if my car passes the MOT emissions test then the cat is efficient enough. My main contribution to reducing pollution is to make as few short trips around my city as possible, and to try my best to burn the minimum of fuel with a relaxed driving style on the longer out-of-town trips.

It seems from owner's experiences that even the cheapest generic converters (I found 5 or 6 alternatives starting from just £150 or so) perform well enough to be comfortably 'legal' when new, but many people report failure in a couple of years or sometimes even less. It seems this terrible lack of longevity might be the real problem - with the long-lasting OEM units, there would most likely be a contributing factor such as oil or fuel contamination that would cause it to fail and break down internally whereas the cheap ones just commit suicide.


I have a 1993 124 sales brochure which proudly announces the efficiency and long life of the new catalytic converters, claiming they'd never need replacement in the life of the car. Hmmm, I suppose that means mine is now in the after-life, then. Either way, what with the bio-degradable wiring, tricksy fuel injection and water-based paint, I am not terribly impressed with MB's early efforts to go 'green', and have even considered swapping to an earlier 124 that's free of these marvelous innovations.
 

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1996 S124 E220 - 1985 VW T3 1.9DG Camper - 1998 BMW E36 328i Cabriolet
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662 Posts
Discussion Starter #5
parts.com still has a price listing for the OEM cat... last I looked it was in the $1600 range.

Really expensive, but at least available for those that are willing to pay for quality. There are of course several extra engine options common in Europe so it's probably safe to say that the six-cylinder specific cats are still available here too, and perhaps the correct diesel parts, but it's curtains for the 4-cylinders. To be fair, I can't imagine that many more OEM cats would be sold for these lower-spec cars now anyway - most are run on a very tight budget if the examples I see around London are representative, and there are few 200's or 220's that are worth much more than the price of a cat left on the roads...

(...apart from the cabriolets. The E220 cabs sold really well here and are still to be seen in fine, low-mileage condition with wealthy / enthusiastic owners.)
 

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Immoderately Caffeinated/ Vintage Moderator
T5
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When I replaced the cat in my VW I was warned the cheaper ones have a stainless case with ordinary steel innards which rust out in 12 months. $1600 for OE starts to look reasonable if it lasts another 20 years. Probably a lot longer than most remaining 124's will last I think.
 

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2008 E350 4M, 2016 Audi Allroad, 2019 Audi Q5
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I've had my high flow magnaflow cat in my wagon 50k miles and 4 years now and blew through 2 emissions tests.

No point going with OEM. It doesn't make economical sense, even if it doesn't last half as long. Not sure about the U.K...but out here get a CARB certified cat and you should be good to go for at least 8 years as long you are not burning oil.
 

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80 280SL, 85 300SD, 87 300TD, 90 300TE 4Matic, 90 300D 2.5 Turbo, 92 300D 2.5 Turbo, 92 300TE 4Mat
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99-C43, 05-G55K, 71-280SL, 94-E320 CAB
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Yes zeitgeist, that's a tricky one. All shops here have the machine and probe to test the exhaust emissions so I suppose a part could be bought, fitted and tested to see if it meets legal requirements and returned under warranty if not. As far as I'm concerned, if my car passes the MOT emissions test then the cat is efficient enough. My main contribution to reducing pollution is to make as few short trips around my city as possible, and to try my best to burn the minimum of fuel with a relaxed driving style on the longer out-of-town trips.
The Magnaflow cats,as mentioned by Ps2cho, especially the high flow spun metal type are inexpensive and have no problem passing a tailpipe emissions.

My M103 TurboTechnics twin turbo uses one in each exhaust pipe.
At curb idle with the tailpipe sniffer it indicated 140 HC PPM and 0.02 CO %...
Oddly enough when dyno tuning we destroyed two sets of very expensive OEM 500SL cats, while the Magnaflow's held up with zero problem.

The best part is that they are less then 100 quid..!!!
 
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