Location of Air Filter Housing 85'300DT

[Alan S]

My air filter is placed up front next to the radiator on the passenger side. All pictures I've seen of other turbodiesels have the air filter housing located up behind the turbo. Has my car been previously modified? or is this just a model year variation. I'm kind of asking because I have a feeling I might need a different air filter than is pictured for my car on fastlane. Mine looks a lot deeper. Thanks

[Alan S]

Thats interesting, the sticker on the drivers door says complies with U.S emissions, nothing about California? What other differences should I be leary of? Where would the trap oxidizer be? Thanks for quick response

[GregS]

I'll tell you what else to be aware of: California versions had a second valve on the intake manifold called an air-recirculation valve. It is a small round valve underneath the EGR valve with one vacuum line connected to it. I don't know exactly what it does, but the valve on my car would produce this unbelievably annoying high pitched wistle that changed tones depending on engine speed. I come from upstate NY, so I certianly knew nothing about such a device, but thanks to some people on the 'net I was able to figure out what was causing the noise and how to fix it - disconnect it!

Good luck,

Greg
'84 300D
165k, California version

[GregS]

Another thing California models have is an electronically operated EGR valve. It is operated by a unit in the passenger side kick panel and a vaccum unit on the passenger inside fender. This unit also actuates the tachometer, which is actually a good thing (I think), because you won't have the broken tach problem lots of people with 300Ds have.

Also, my car at least, does not have the vaccum unit on top of the valve cover that modulates transmission shift points. This unit is something that gives lots of people with 123 diesels headaches, so again, I feel fortunate I do not have it!

Greg

[Alan S]

Well, surprise, surprise. You are right Bill, it is a California car, I just saw the emission sticker under the hood. Ok, so I started looking for the trap oxidizer on top of the turbo, there is nothing, the turbo is in full view. I can't even tell where the thing was mounted. I wonder if there is a picture out there where I can verify. Anyway, any other differences I should pay attention to, so far, I've been ordering parts for a federal 300d, and have ran into no problems, until I saw the picture of the air filter. As I mentioned earlier, mine is round and about 6" deep. Thanks again for the quick replies

[Alan S]

Ok guys, I'm starting to worry about this trap oxidizer. I don't have anything on top of the turbo, however, below the turbo is a huge silver can looking thing with a couple of numbers on it, they are #1123 196 250 00, 126 490 3414 and the word eberspacher. Any clues what that is? Thanks again for all the help.

I have one as you do. I will get you a part number tomorrow for the Mann air filter. It is about 3 times thicker than the "standard" one. You found the Trap Oxidizer or Cad replacement. There was a recall on these. Mercedes will replace them one time only. If you go to a dealer they can run the history of your car and see if it was indeed replaced. They also some times replace the turbo. But it is their call. What other wonderful things do you have. There is a Calif. starter that hangs up side down from normal and is and extra $100 for it. It's special. Do you need the cat.,egr,special starter? No you can have someone remove the cat. and cut the frlanges off and replace with straight pipe and block the egr valve and use regular starters. But that is removing smog equipment which we don't need on deisels because they don't smog them. So it would be by customer reguest. Charlie

[gsxr]

1- The trap oxidizer was used on the 1985 300D in California only and mounds UNDER the turbo. That is the big silver can you see. Mercedes will replace it free if it hasn't been done already. It is replaced with an oxidation catalyst (different can). They will not replace the turbo. On 1986/87 models (with a totally different engine) the trap was mounted on TOP of the turbo, and if it failed it could damage the turbocharger itself. If that happened, MB would replace the turbo under warranty. On the 1985 models it's not possible for a trap failure to damage the turbo - so don't lose sleep over this!

2- The air recirculation valve is on the turbo itself, not the intake manifold. It is installed on 1984 CA models and all 1985 models (CA and 49-state "Federal"). It's purpose is to enhance the operation of the EGR and trap oxidizer by reducing boost pressure under certain conditions. You want to disconnect and plug the lines to BOTH the EGR valve as well as the air recirc valve.

3- There are a LOT of differences on the 1985 300D compared to the 1984 and older 300D's. The tranny is different, torque converter, rear axle ratios, more electronic widgets, and all sort of misc. items. Mostly they're all GOOD things, as it was the last year the car was made and MB was putting some new technology items on that were used in the 86-up W124's. Nice car!


Regards,

[Alan S]

Thanks for the replies fella's, as a matter of fact, I did lose sleep, last night to be exact. I was worried about the turbo and all the other California "stuff". I called a dealer this morning and they looked up the vin. The trap was removed and replaced with the other can thing back in 1998, the turbo is shiny, so I imagine that was replaced as well. I'm somewhat relieved, although I would like to know how reliable is that new thing they installed? Has it proven trouble free? By plugging up the air recirc and egr valves, what do I gain and what do I lose? Thanks

[gsxr]

The new thingy that has been installed is a totally different animal, and so far appears to be perfectly reliable. I have not heard one complaint from anyone with the new part. And like I said before, it's downstream of the turbo on your car, so there is absolutely NOTHING it can do to harm your engine or turbocharger!

By plugging the EGR and ARV you (may) gain some horsepower and some MPG, depending on if they were functioning properly in the first place. You lose exactly nothing other than emitting a few percent more oxides of nitrogen or some other such silly thing. You also gain a cleaner intake manifold, because you're no longer dumping sooty exhaust back into it! See photos at the URL before of an OM603 intake charge pipe, to see what the EGR lets into your engine (it's the "pipe before & after" photos):

http://www.meimann.com/images/mercedes/OM603_intake/



Regards,

[Alan S]

Thanks GSXR, would I need to plug everything up, or do I leave some things open to the atmosphere? I hope I'm making sense, what I'm trying to say is for example, on the arv, do I plug the hose going to it as well as the nipple on the arv? same with the egr? Many thanks

[gsxr]

You *must* plug the hoses, but not the nipples on the EGR and ARV. You can cap them off too if you want, but it won't hurt anything if you don't.