Duovalve Removal and cleaning

[iluvjesus]

Thanks Matt, when I turn off the car and hit the rest button, the side vents blow again, not that warm though. I have the following questions.

1. I know duo valve DTC should be 1417 and 1418, but could the duo valve blockage cause DTC 1416? I am hoping it can because this is an expensive part.

2. When I remove the aux coolant pump for test, should I clamp those 2 hoses or just let the coolant flow and add back some later?

3. Any tricks on removing the clips/clamps on the hose? Do I have to break them?

Thank you.

Just for reference:

[Jeremy5848]

Originally Posted by Matt L

Absolutely you should. The 124 auxiliary water pump, when it goes bad, will burn out its climate control unit. I haven't heard of this on the 210, but maybe that's just because the 210 is a newer car and they haven't been failing much yet.

The W124 and later models CCU is internally current-limited; it won't burn out if the aux coolant pump seizes. It's the W123 CCU that is at risk; owners should fuse the pump (1-2 Amps max).

[Kajtek1]

I had that pump bad on W210 and it is using magnet as a clutch. Meaning frozen pump will not freeze the motor. I know that the recirculating pump in ML runs some time after turning off the ignition to eliminate "hot spots" in the engine. Haven't notice that in E, but after being married for more than 1/4 of Century I don't hear everything anymore.

[iluvjesus]

I tapped on the aux pump motor, and it works intermittently. I suspect the graphite brushes are gone, is it possible to fix it? Or I have to replace a new one, it is an expensive part. Thank you for your advise.

[Matt L]

Originally Posted by Jeremy5848

The W124 and later models CCU is internally current-limited; it won't burn out if the aux coolant pump seizes. It's the W123 CCU that is at risk; owners should fuse the pump (1-2 Amps max).

That's good to know, Jeremy. I wasn't sure, but I also haven't heard of the problem in a 210.

[Kajtek1]

Originally Posted by iluvjesus

I tapped on the aux pump motor, and it works intermittently. I suspect the graphite brushes are gone, is it possible to fix it? Or I have to replace a new one, it is an expensive part. Thank you for your advise.

Those pumps are not serviceable. I hesitate to spend $200 + for a new one as well, but was able to find used one on junk yard. Not too many older pumps have triple hose for windshield fluid heater, but I found one on older S class. Than you can just plug the extra hose and use pump from other models. As far as I know you don't get too much freezing in HK ?

[iluvjesus]

Thanks again KT1, no freezing in HK at all. I will take your advise and look for one in the junk yard. Thanks for telling me other models' pump would work too. My I ask, when you replace it, do you clamp the hoses or just let the coolant flow and refill later?