Duovalve Disassembly and Cleaning Question - PeachParts Mercedes-Benz Forum

shertex · #1 05-09-2015, 01:51 PM

Replaced the duovalve on my 99 this morning. With the old one out, I decided to clean it and see if there's any rubber disintegration, etc...

Looks to be in good shape...all cleaned up now.

One question: picture the upper section of the duovalve, with the metal plate on top and the two-spring loaded pistons. Can/should this be taken apart? If so, how? I've read various cleaning threads and it seems that, with some duovalves, you can simply pull out those plungers....not on mine.

Part number is 001 830 78 84.

treetops · #2 05-09-2015, 11:55 PM

Not sure but the PP shows that sometime the plate get stuck, fig 4 & 5 in the link

Pelican Technical Article - Mercedes W210 - Heater Control Valve (Duo-Valve) Disassembly and Cleaning

I see you are selling the old duovalve, would you say that after cleaning it, it is now a viable fix for the issue you were having. I ask because my HVAC is flukey-Hot HOT on side vents with AC on and only cold air coming out of the center vents and sometimes not so cool air on the drivers side. I have recharged the AC, but still have this issue and thinking cleaning or buying a duovalve is the next step.
Thanks.

shertex · #3 05-10-2015, 06:46 AM

No, the plate is not stuck. It separates completely but is held by the springed assembly.

I was certain that my problem was the duovalve (driver side sticking open). Now that I've cleaned everything, I assume it works fine....but have no way of confirming.

One thing you can try: when the system is running and blowing hot when it should be blowing cold, hit the duovalve repeatedly with a mallet. Oftentimes that will dislodged whatever is sticking and you'll have cold air again.

treetops · #4 06-21-2015, 11:39 AM

Did you ever find a way to pull those plungers? I just worked on mine and they were in real tight, so much that I didnt want to bugger it. I ended up taking to top half of the valve off and cleaning them the best I could.

Same deal, metal plate was not stuck, but the top of the plunger would not come off.

Thanks.

shertex · #5 06-22-2015, 07:05 AM

No, never did. I wonder if ours have a slightly different design than that of some others.

treetops · #6 07-17-2015, 07:26 AM

Duovalve. I came across this on BW this morning. Perhaps others with the E300 TD can chime in with success in taking apart their DVs. I thought it interesting.

Courtesy of gsxr: "I didn't see this mentioned elsewhere, and it would be really helpful if this was added to the first post in this thread:

The 1997 E420 (210.072) duovalve is COMPLETELY different, and cannot be easily dis-assembled for cleaning / repair. The same valve is also used on the 1998-1999 E300 turbodiesels (210.025) and CDI (210.026). More details in this thread: E420 Duovalve - A Cautionary Tale - Mercedes-Benz Forum"

Main thread here Duovalve Removal and cleaning - Page 10 - Mercedes-Benz Forum

shertex · #7 07-17-2015, 08:02 AM

That's interesting....so I guess they can be cleaned to some degree, but just can't be taken apart to the extent that some others can.