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Now for the tricky part. The plunger that operates the valve is a specific length. It is designed to work with the plastic POS that has nothing on the back of the valve. With the pop rivet we now have a "seat" that's going to sit on the plunger.

The plunger must be ground down so the valve will open when the plunger is in the "up" position. Here's the difference.

The rivet seat is around .035" so grind down the plunger that amount. It just so happens that the notch cut in the plunger is close to that number, so just grind it down until the notch is gone. . .

Dremel in a couple of notches. . .

Rinse off all the shavings and junk, slide your newly updated valves into the plungers . . .

Carefully reassemble. Here's the final product!!!! Congradulations, you just save a couple hundred bucks!!!

 

Nice

work!true grit and diy innovation.
:bowdown:

 

whats a duovalve

 

Duo

two valve system that allows the flow of engine coolant into the climate control system that on these model mercedes is a shared system both hot and cool are always avail on demand as the system calls for them with the climate control.
Bad valve or stuck valve and your a/c could be on and have it blowing hot air on one side and cold air on the other or depending where the valve is stuck someplace between the two extremes.Sometimes a whack with a screw driver handle will free them up,just don't whack to hard.

 

Thanks

 

Thanks for the great DIY....

-JOE55

 

I wish I could say I did it for better reasons. My motivation was the thought of being screwed by the dealer for a couple hundred bucks. All for a part that probably costs less than a dime to make. Spend the money and you get the same piece of junk. They should be ashamed of themselves. Almost like they've been following the Chrysler business model. MB has a lot of "brand" issues they need to repair.


I've only owned the car about a month. It's a 98 E300 TD. I'm still wondering if I should just keep my 92 300D 2.5 and get rid of this thing. It's built like an MB should be. The build quality of the 98 car concerns me. Already busted a window regulator. I do love the power and the quiet of the 98 though. It's roomier, looks more modern and at times is a little easier to work on.


I just hate when I have to replace a broken junk part with an expensive new junk part. So you can count on me for future work-a-rounds!


Okay, I'm off my box now.

 

for us novices, where do you find this part to get at it, remove it, and try this out...? also if htere were specific part and part numbers you used when putting this new valve together, i'm sure we'd be interested when/if we have to attempt this.

thanks for posting it!

F

 

He made

the parts or had a buddy make them in a machine shop.
Do you have problems with your a/c system?
if not the typical cool on one side and hot on the other,there is no need to go into the duo valve(located in the area where the ecu and tcu are right in front of them on the pass side back by the firewall,look like two little brushed alum beer cans sitting side by side)
:bowdown:

 

yeah i have had that problem intermittently but not for quite a while now. in fact i think that only happened once w/ this car...

by pass side do you mean it's accessed on the interior or via opening up the hood? just curious.

 

Hey, FJ, look in the removal/cleaning DIY I just freshened, there are pics (worth a thousand posts, er words, right?).

Or I still have the link to the pics, so here's one that will help you ID it:

Take care and enjoy the ride,
Greg

 

No special tools are required. No machine shop work either. I used all the original parts inside the valve. The only thing new is the pop rivets, available at any home depot, auto parts store.

 

engine comp

up by the firewall just in front of the black cover that has a label listing some engine specs and a/c charge specs,find that and then just move your eyes toward the front of the car a bit and you will see the two valve cans in that open recess.Most times a firm whack with a handle of a screw driver will free them up if they are sticking and the drivers side is warm and the pass side is cool with the a/c on.
:bowdown:

 

awesome, thanks guys!

 

After taking my duovalve apart on my W210 E420 for a clean up I noticed one of the valves had a broken stem. Tried 5 times to glue it but as soon as it was entered into the duovalve and then put back together it would snap again!

 

I took apart the duovalve and I didn't see any damage on the valves. There were a few small (1/16" to 1/8") brown chips that looked like plastic so something must be wrong but I couldn't find any damaged part. The stems were in place and everything else was clean. I'll have to take it apart again for another look for chips on the stem.

 

Can you take some pictures for us to have a look as well? Thanks Joe.

 

My Duovalve is like this:

(credit to gt4rcdude)

I am finding that the plungers are sticking within the duovalve body. How do I dismantle further to clean/lube?

Thanks
Steve

 

I'm in awe of these forums and the knowledge and resourcefulness that are shared. This seems like exactly what I'll need to get mine working. Anyone know how these stems get broken? My guess is that a lot of owners break them taking the duovalve apart while it is still in the car (the 5 screws that hold the solenoid covers on). I'm pretty sure that's how I broke mine.

Perhaps we should make a bigger point to others when they are working on them to NOT take that stuff apart while in the car, or if they do, to be VERY careful not to do anything but lift straight off? I'm not sure if there is a way to disassemble this in the car without serious risk of breaking the poppits and/or losing the parts down the hole. First time I took it apart, I certainly wasn't expecting those parts to be loose and falling out/breaking.

 

this is great tinkering :thumbsup: