Trap bypass pipe for '85 300TD Cali version? - PeachParts Mercedes-Benz Forum

Aaron · #1 07-23-2014, 11:20 AM

Hey all,

Does anyone happen to know if MB ever officially made a trap bypass pipe for the W123 California models as part of their modification? I've heard conflicting information from two different MB dealer oldtimers. One said they did and that they then installed a catalyst inline in the front pipe under the passenger's side floor and the other guy said they just kept replacing the traps (or oxycats?) directly underneath the turbo. The '85 TD I just got still has the football-shaped trap under the turbo and, according to my local dealer, the recall has been done on this car. I want to eliminate this as a matter of future precaution and so far, the easiest way I've determined to do this is to swap over a complete federal setup. Thanks all for any input!

charmalu · #2 07-23-2014, 12:40 PM

ROLLGUY is making the test pipe you are looking for, he has a thread about his pipe.

It might have been with the 60x engines in the w124 and w123 that they installed the catalyst thing down stream from the engine as I remember.

The W123 kept the Trap/Catalyst in the location under the manifolds. MB replace the traps every 30K milts as part of the emission requirements. then later they upgraded the Trap to one that didn`t have to be replaced.

I have an 85 and had this upgraded replacement done many years ago.

If it was me, I would just source the federal parts and just swap the whole thing.

PeachPartsWiki: Calf. to Fed. Emissions Conversion

Charlie

Aaron · #3 07-23-2014, 01:28 PM

Thanks Charlie, I'll look up ROLLGUY's thread. My car has had the upgrade done but I'd feel better about eliminating it altogether.

charmalu · #4 07-23-2014, 04:07 PM

At sea level the 85 runs good, but get up to high altitude, it will be on it`s knees. As I have mentioned in other threads, we were in Colorado at a resort near Vail called keystone. Elevation it up around 9000ft and higher. It had no get up an go. got beat down hill by a 61 VW. LOL.

Changed every thing over to as a 83 300D is, and the next year you would have not known it was the same car when we went back. That Cali emissions really chokes them down.

Scary when you punch it to go and not much happens.

Charlie

Jeremy5848 · #5 07-24-2014, 02:01 AM

Quote:

Originally Posted by Aaron

Hey all,

Does anyone happen to know if MB ever officially made a trap bypass pipe for the W123 California models as part of their modification? I've heard conflicting information from two different MB dealer oldtimers. One said they did and that they then installed a catalyst inline in the front pipe under the passenger's side floor and the other guy said they just kept replacing the traps (or oxycats?) directly underneath the turbo. The '85 TD I just got still has the football-shaped trap under the turbo and, according to my local dealer, the recall has been done on this car. I want to eliminate this as a matter of future precaution and so far, the easiest way I've determined to do this is to swap over a complete federal setup. Thanks all for any input!

For the 1985 California OM617 engine (I owned one), the original "trap oxidizer" had to be replaced every 30,000 miles by a dealer, on warranty, no charge to customer. A couple of years later, Mercedes created the "trap catalyst," which was a permanent replacement and was installed again at no charge. The two are so close in appearance that you might not be able to tell them apart. They go in the same place and have the same negative effect on performance. Mercedes never made a "straight pipe" bypass for the OM617 but several people (including me) have done homemade bypass pipes to replace the trap cat (for testing purposes only, of course, since it violates smog laws). Someone on the forum was selling bypass pipes for about $200, I think. The OM617 engine runs much better without the trap cat!

The OM603 engine in the 1987 W124 came with a similar "football" trap cat from the factory but pieces breaking off of the insides of the trap cat damaged so many turbochargers that MB changed the design. In a recall campaign starting about 1991, the trap was replaced with a straight pipe, a new exhaust pipe setup including a catalyst down under the floor, and in some cases a complete new exhaust system. I was really lucky--when I had the "recall" done, the dealer replaced the entire exhaust system and even the turbocharger at no cost because it had been damaged. This recall is still active for cars that have never been converted (1987 300D and 300SDL). A dealer can look up the VIN and see whether it has been done for that car. Clearly, very few unmodified cars are still out there.

These two different models (123 and 124/126) tend to be confused in any discussion of trap catalysts; there is a lot of misinformation running around as you have discovered.

Jeremy

Aaron · #6 07-24-2014, 07:37 AM

Hi Jeremy,

Thanks for the reply. I'm very familiar with the 603 setup, just haven't ever dealt with a CA spec W123 since I'm on the right coast, so since I pulled the trigger on one, figuring MB had done a similar setup, I realize now that they didn't. Need to track down one of those bypass pipes as the speed shop I sent my trap to wanted a week's worth of labor to build a jig in order to make a bypass pipe--so it would have cost almost $2K in time and materials---yikes!

Jeremy5848 · #7 07-24-2014, 05:34 PM

I had a bypass built from exhaust pipe bits and the flanges sawed off of a junkyard trap cat. (The junkyard wouldn't sell the entire cat, claimed California or Federal law forbade it; they didn't have a problem with my friend hacksawing off the flanges though, so he got them for me.) Here in Northern California, 5 years ago, the bypass pipe cost me $400. The machinist/welder used my existing trap cat to create a crude jig, then welded the bits and pieces together. The fit was almost perfect.

Do some searching in this forum; you should find someone with a desigjn ready to go.

Jeremy

mach4 · #8 07-24-2014, 05:53 PM

Try this - 1985 CA emission 617 owners, You NEED This: