w124 duo valve information sought

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jjrodger

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Apr 7, 2004
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I am an infrequent poster here, so I will say hello.

I have a s124 E300 diesel T (124.191).

The car has factory fit air conditioning.

The heater on the driver's side defaults to hot and only very slowly goes to cool and only then if I set it to maximum cold. The passenger side seems fine.

I suspect the duo valve is kaput, as does my mechanic.

According to the EPC, my diesel requires the valve with part number A0018303884.

Most valves for sale on Ebay are part number A0018303784. Many sellers (and the German SPOB site) indicate that this latter valve is not suitable for the E300 diesel.

Is this correct? Or can I use the A0018303784 duo valve without any problems? There is a huge difference in price.

Thanks in advance for your help.
 
I had a go at stripping it following a different set of instructions and I couldn't get it apart. To be honest, my tinkering time is severely limited by domestic and professional commitments and it is easier--if less satisfying--on this occasion just to replace it.
 
The E300 Diesel Duovalve is different to other W124s

Nick Froome
 
The E300 Diesel Duovalve is different to other W124s

Nick Froome

The answer I feared. Do you know why? Just out of interest. I ask because on the German SPOB site, whereas the 3784 valve is not listed as compatible with the E300 diesel, the 3884 valve is listed as compatible with all cars. Likewise the EPC. In other words, you can use the facelift diesel duovalve on any car but you can't use any other duovalve on the facelift diesel.

I'll have another go at cleaning it out. I couldn't get the lids off, following this (210) link: http://www.mbclub.co.uk/forums/engine/26854-howto-clean-duovalve.html

Cheapest used one I can find is £200. At that price, I'd rather spring for a new one at £350.
 
If you look at the picture of A00183033884 on that SPOB site you will see that the more expensive valve has 1/2 extra inlets/ outlets ? on it. Further to that the description of the cheaper A00183033874 it is described as "fits to models without park heating" from that I assume the 300 comes with "park heating" as standard. don't think its just "diesel" related as the 250 diesel lists the cheaper valve as suitable. Do you have a fuel powered preheater fitted?
 
i'm not sure how different your duo valve is, I used the link you quoted when doing mine and found it pretty straight forward, although the valve was completely off the car at the time.
Mine was just a case of one valve stuck, just needed a good clean and all good.
Good luck with yours
 
I dismantled it and cleaned it just now. It seems a bit simpler than the 210 version. Anyway, I'll find out whether it made a difference later.

By way of observation, the duovalve in my car is not the A0018303884 version shown on the German-SPOB website. It lacks the additional outlets. My car does not have the aux heater (I do not think it was available in the UK). The duovalve on my car looks identical to the A0018303784 item. I suspect the EPC is wrong.
 
It seems fixed. We'll see. It still blows hot at first but it doesn't stay hot and is quickly adjustable. Thanks to all who helped me with this.
 

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