Any tips on replacing W210 Duovalve?
 

Yes, I know about cleaning without removing. But for $239 shipped I decided just to replace it and be done with it. It's had a good, long life. Some folks had the experience of cleaning it only to have it act up again within a few weeks.

Even though it looks like a pretty straightforward job, there doesn't seem to be much room to work in that little area. Any tips, suggestions? This is helpful: http://www.pelicanparts.com/techarticles/Mercedes-Benz/19-WATER-Cleaning_Heater_Control_Valve/19-WATER-Cleaning_Heater_Control_Valve.htm

I can clamp the hoses and assume I won't lose too much coolant from the housing.

I would drain off a couple quarts via the petcock into a clean container.

If you remove the retention clips to take off the top half of the valve be sure to hold on to them or tie them off with a string. I took my valve top off and spent 1/2 hour cleaning and reinstalling. And 6 hours tearing apart the control box to find the dropped clip.

When you go to reassemble then using a clean funnel and coffee filter pour the coolant back in via the upper hose and burp the system same as if you were doing a coolant change.

Thanks for the heads up, Jay Bob.

One of the clips is sticking out a bit....so I can envision how I could secure it with string or wire and pop it out with a flat blade screwdriver. But the other clip is not protruding at all....so it's not obvious to me how I even grab a hold of it to pull it out.

Searching for small clips is not my idea of fun. I still remember having the C-clip on the wastegate actuator on my 91 go flying when I popped it out. Still can't believe I actually found the thing!

KarTek's description also helpful:

http://www.peachparts.com/shopforum/tech-help/242566-how-i-fixed-my-duovalve-w210-got-my-heat-back-saved-myself-$250.html

Nothing is easy....trouble pulling things apart....safe to say I won't make it under the 48 minutes shop time!

Lots of trouble pulling hoses off...will try to free up bottom of valve first.

Red ribbon tied to retention clips....no fear of loss in the abyss! :eek:

In case it may be of help to anyone else doing this for the first time....

1. No need to drain coolant. With hoses clamped, I lost virtually no coolant...no flow at all from heater core.

2. With the duovalve still seated in place, I had a very difficult time removing the hoses. I found that, once I unseated it and removed the electrical connector, I had an easier time removing the hoses.

3. When installing the new one, I made the mistake of attaching the upper hose first. This made it virtually impossible to grip and maneuver the clamp for the lower hose. So I had to reverse the order. Not sure what the advantage is of that style of clamp....seems like clamps that tighten with a ratchet would be easier to work with.