Aiflow meter pot source - Bosch CIS
 

I have just ordered the feedback pot for my airflow meter ('91 190E 2.3) from a place that sells Bosch generic parts. A source was listed previously in Russia, but giving out my CC# to them was not for me. This location is in VA, and I'll report back how the transaction goes. Price is $71 with $9 shipping, and tax if in VA:

https://www.olyonline.com

BTW, the part# for mine is 3437 224 035, which is the same as someone listed for a W124 engine - but I don't recall which one.

Steve

The part just arrived tonight, and it appears identical - and does have the same part #. Two weeks for a special order Bosch part - not bad since the car has been working ok since, with the old one and some wiper-tweaking I did. I don't know when I'll install it, since I want plenty of time to get the new one as identical to the old as possible when I tighten the screws. Pics of old vs. new:

new:

here is the detail of the wiper arm that sweeps the pot elements:

and, old and new shots show the surprise hidden adjustment, presumably a trimpot, from the outside view:

Oops!

There are three adjustments on reassembly, which could make this a lot of fun:

-the hidden trimpot
-the whole body rotates about the wiper arm axis a few degrees
-there is an adjustment of some sort inside the wiper arm pivot, in the body of the airflow meter unit

Sbourg,

I appreciate the photos and the info. From what I`ve read, setting those replacement pots can be a pain.

Keep us posted and let us know the results after you swap it out.

Tinker

Not sure I wll be replacing this soon - sometime this summer, though, or immediately if problems return.

Note the exacto knife scribe mark I made on the body of the airflow meter BEFORE the first time I removed the pot. Very important to have a reference whether putting back the original or using the old one as a reference for the new.

Steve

Did you have to remove the intake-fuel distributor from the engine?

Your 6 may be different from my 4, but the only things I removed were the air cleaner housing, the bolt securing the pressure regulator, and the fuel connection from the regulator to the fuel distributor. Worst case, I could envision you might have to remove one or more of he injector lines in a 6.

The 4 screws retaining the pot are hidden under pry-off covers, then the pot just lifts out. Don't forget the scribe mark! Note the white streaks on the element of the old pot. This is where the wiper brush has worn thru the deposited resistance element to the ceramic substrate. No amount of cleaning or abrasion with eraser will replace the missing conductor. When the wiper brush hits the white spots, contact is opened.

My temp fix involved slightly bending the brush wires to the side to contact new material. This way, some of them are likely to retain contact with the unabraded surface. This is a very delicate and dicey procedure that I wouldn't recommend to anyone not willing to replace the whole airflow meter if it goes awry.

Steve

Please keep us abreast of any new developments with the installation of the poteniometer!

anyone know the part # for this part for the 86 190e 16v,
i think i need one, and that site only sells the whole pot for
600.00, in there search engine , i have a extra pot i would like to rebuild,
thanks
Dave

The part# is a Bosch one - not Mercedes - and is clearly marked on the outside. You can see the number for this one in the pics I posted. Do a search on that site for Bosch parts.

Steve

here is a excellent bosch site i found this afternoon,
http://www.boschusa.com/home.asp
it gives most of the MB bosch fuel injection part # for the 16v and the 8v,
The plus is that it tells you the closest place to you that can get
bosch parts, my local Acme auto, or pep boys told me 64.00 for the little black meter or 399.00 for the whole air flow meter new!! Alot better then the 650 they want at MB dealer with the club discount.