Date registered: Aug 2002
Vehicle: 2002 s500, 2004 S500 fourmatic
Location: kitchener, ontario,canada
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Quoted: 1 Post(s)
When I changed the duovalve pump motor, I also changed the antifreeze/coolant at the same time. If everything was working before you did the activity, I'm almost 100% sure that you have an air bubble (large) in the heating lines preventing the flow of fluid. I actually had similar results initially, but I knew that the duovalve pump is situated high on the firewall and expected this kind of problem, so, I parked the car on an angle (front end high) to help the trapped bubble of air escape. Helped a little, but what is really going to help the most in this case, is alternate heating and cooling. With the system under pressure, it will dissolve a little of the air into the coolant. When it cools down, the air will displace, but into a different area of the engine. Over a few cycles, the heater hoses/heat exchanger blockage will go away, but you will now need to add more coolant to make up for the space consumed. Check your coolant reservoir when it has cooled down to see if it needs more coolant. It will probably just be a time thing.
I seem to remember that I only required (2) gallons of antifreeze to charge the system, but, when I installed the new pump, I had it mis-aligned (off 90 degrees) and lost some antifreeze through the imperfect sealing.
Last edited by tower; 12-27-2011 at 04:18 AM.