I just finished replacing the water pump, belt, and hoses (all of them) on my 1988 mb 300e. It started up just fine and there seems to be no massive leaks anywhere, however coolant is not making it to the heater core. The circulating pump is not working and I have not yet checked to determine if the water solenoid valve is operating. Any helpful hints/clever ways of troubleshooting these two items would be greatly appreciated. Thanks, Roy in Louisiana.
It's air bound; you need to bleed the air from the cooling system.
Make sure you have bled the coolant at the top of the thermostat housing(12mm bolt). Add coolant until it comes out of bleed screw. Start engine and put ACC into the defrost position. Leave the top off the expansion tank so coolant will flow into engine. The monovalve normally fails in the open position (full heat) so I would check the fuse for the aux coolant pump first. Run the engine at
1200-1500RPM once the temp gauge gets to 75-80C. Even witht he aux pump not running, there should be coolant flow to the heater core.Dick
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