W124 heater problem. Help!
 

This week it got too cold here in Uzbekistan. The temperatures went down as -10 degrees in Celcius. At these temperatures I am having problems heating the interior with this type of weather. My car has a duovalve type heating system. I only get warm (almost like cold) air from the heater. I know exactly that the duovalves are working correctly however it seems like the amount of water passing through the hoses is very small. The engine temperature stays at about 80 degrees. My mechanic once told me that I am missing some electic water pump that circulates the water through the heating system when the heater is on. He also showed where it should be installed. It was nearby the windshield water fluid tank. Does this electric water pump really exist? What type of expenses are we talking about here?
Please help.

If your temp. gauge is accurate (temp. sending unit) 80Deg is too cold. It should run near95deg in winter. Your thermostat may be defective.
You should have auxiliary electric water pump on your car. It circulates hot water throught the heating system, but mostly at low spped (low engine rev.)
JackD

check the mono valve on the firewall. you should be able to get the repair kit

thermostat
 

I agree with Jackd - get your thermostat checked. BTW, I also have a duo-valve equipped heating system and I found that as the engine temp reached around 60Deg the interior starts to heat up.

If the thermostat checks out OK it might be worth-while to flish the heater core.

One other point _ when I last worked on the heating system of my car I found that one of the copper end points (the actual valve) broke off the stem and was blocking water flow. It is a fairly tricky assembly procedure if you do not want to break anything...

Ad Jackd stated, thae aux pump only helps in slow going traffic or at low engine speed to ensure an even temp inside the car.

Come to think of it - without the aux pump, what does the plumbing between the radiator hose and the heater core look like ?

good luck
L