Bl00dy duo valves.

[coupe deville]

When I bought the car the heater temp was full hot, this forum gave me the know how to strip/clean the duo valve. Been perfect up to now, now its back to full hot. I thought the duo valve would be ok so I've been checking other stuff, fuses, cabin temp sensor and vacuum, heater controls etc. After no joy I finally tested duo valve. 12v battery across both sides, 1 clicked, 1 didn't. Checked resistance, The good one is 17 ohms, The other is only 2 ohms. Took it apart and it looks like water has got into the coil. I'm going to refit it and leave it unplugged until I source a used one from a breakers or Ebay or somewhere. Not too much of an hardship this weather.
Question, what is the other motor alongside the duo valve [ car is 93 e320 coupe and should I leave that unplugged while duo valve is unplugged.

 

[230K]

Hi

The other motor alongside duo valve should be the auxillary water pump for the heating, it will cause no problem if left dis-connected.

230k

 

[kth286]

That other motor is the circulation pump and comes on after the engine is switched off if the temperature exceeds a certain level.

It then runs and keeps the water circulating to avoid engine hot spots, and also to avoid formation of coolant vapour bubbles, so it IS important to keep it connected.

 

[Druk]

spare

There's a duovalve here from a 93 320TE. Part number 001 830 37 84 including the circulating pump. Was working when it came outa the car a couple of years ago. Make me an offer.

ps. explain how to check the resistance and I'll make sure it's OK.

 

[230K]

That other motor is the circulation pump and comes on after the engine is switched off if the temperature exceeds a certain level.

It then runs and keeps the water circulating to avoid engine hot spots, and also to avoid formation of coolant vapour bubbles, so it IS important to keep it connected.

If this is true i stand corrected. What temperature does it kick in at?? The one in my 300td is inoperative and the heating is poor when the car is at idle which made me assume that it was for circulating the heating water. The one on my 210 works and i will check if it runs after a good blast.

230K

 

[coupe deville]

There's a duovalve here from a 93 320TE. Part number 001 830 37 84 including the circulating pump. Was working when it came outa the car a couple of years ago. Make me an offer.

ps. explain how to check the resistance and I'll make sure it's OK.

you need a multimeter set on resistance [ohms] range, put it to the 20 ohms setting and connect one probe to centre pin and other to one of the outside pins, should be about 17ohms, check other coil same as, probe on centre pin and other probe on the other outside pin, should be about 17 ohms. If you connect a 12v battery [ a 9v might work, like in a smoke detector] + on centre pin, - on one of the outside pins you should hear the plunger clicking, check both sides
Thanks for the offer Druk, Ive PM'd you

 

[Druk]

OK Dave I'll do the test tomoro. Replied to your pm before I read this. Doh.

 

[kth286]

230k

If the coolant temp after engine switch off is greater than 110C, the temp is monitored for 1.5 minutes. If the coolant temp continues to rise above 110C
during this time as a result of the hot engine, the pump starts the coolant flowing for a max of 10 minutes.

 

[230K]

230k

If the coolant temp after engine switch off is greater than 110C, the temp is monitored for 1.5 minutes. If the coolant temp continues to rise above 110C
during this time as a result of the hot engine, the pump starts the coolant flowing for a max of 10 minutes.

Thanks for that, i would never get the Turbodiesel up to that temp to test it but it seems sensible not to leave it disconnected if you plan on running high temps.

Thanks,

230k

 

[coupe deville]

There's a duovalve here from a 93 320TE. Part number 001 830 37 84 including the circulating pump. Was working when it came outa the car a couple of years ago. Make me an offer.

Valve arrived this morning and now fitted and working and cabin temp control back to how MB intended. Thanks Derek, cheques in the post. [bargain] Mucho Obrigado

 

[Druk]

Happy days.