Duo valve test?

[mercmadjim]

Is there any way to test the duo valve? I have voltage going to it, but using a multi meter, can I test the valve itself?

 

[Number_Cruncher]

Measure the resistance between the centre terminal and each outer terminal, and report back.

 

[mercmadjim]

Measure the resistance between the centre terminal and each outer terminal, and report back.

I did that and got nothing..zip, nada, etc, is it broken?

 

[television]

The reading should be read on the 1k range, its unusual to have both coils O/C unless say the passenger one failed some time ago and you did not notice.

You can remove the top and see if there is a broken wire from the coils, though they often break on the inner part of the coil, a break on the outer turns is easy to repair, but not the inner
http://forums.mercedesclub.org.uk/showthread.php?t=25909

 

[basamir]

I did that and got nothing..zip, nada, etc, is it broken?

If no resistance are between pins that means that your solenoid are broken.
You can repair them all that you need is to repect the topic linked in malcolm's reply.

I have me too problems with my duo valve but they aren't broken because the resistance between pins are the same 0.20 Ohms

 

[mercmadjim]

Thank you Malcolm, any idea how much they cost? my old W124 has a good one, the pipe work is slightly different, on the SLK all 3 pipes come out on 1 side, and on the W124 there is 2 on one side and 1 on the other.
But if they are reasonably priced I will buy one.

Thank you Basamir, there is no thank you button on your post??

 

[basamir]

Thank you Malcolm, any idea how much they cost? my old W124 has a good one, the pipe work is slightly different, on the SLK all 3 pipes come out on 1 side, and on the W124 there is 2 on one side and 1 on the other.
But if they are reasonably priced I will buy one.

I think that a new duo valve is about 100 Euros.

 

[television]

If no resistance are between pins that means that your solenoid are broken.
You can repair them all that you need is to repect the topic linked in malcolm's reply.

I have me too problems with my duo valve but they aren't broken because the resistance between pins are the same 0.20 Ohms

One will be stuck

http://forums.mercedesclub.org.uk/showthread.php?t=25909

 

[Slowtack]

Had duo valve problem last year on my W124 estate.
No heat either side, solenoids ok.
My canny mechanic guru fixed it by taking out the internal rubber grommets which were swollen on one side and replacing them the oposite way around.

 

[television]

Had duo valve problem last year on my W124 estate.
No heat either side, solenoids ok.
My canny mechanic guru fixed it by taking out the internal rubber grommets which were swollen on one side and replacing them the oposite way around.

Yes and a good fix

 

[fullmeister]

Are the internal seals availible for rebuiling purposes ? I took mine apart to clean it and now it leaks like buggery

 

[television]

They were not made to be repaired,,it is possible to make your own gaskets, and O rings can be bought in any size.

Cleanliness of the joint faces is very important. I will try and dig up a link that covers this if I can find it

 

[Parrot of Doom]

They can be repaired:

http://www.peachparts.com/shopforum/showthread.php?t=242566&highlight=duovalve

The solenoids can also be repaired, but you need a length of the correct gauge wire, and you need to measure it out before rewinding.

 

[fullmeister]

Cheers lads but I decided to get a scrapyard one (12 quid) , when I removed the top covers the windings were like a birds nest !

Top link though.........