As is so often the case with automotive problems, there were 2 problems with my heat and they were not related. 1. A bad thermostat - opened too early, so the coolant barely reached 60C. This was a Behr thermostat which I tested before installing earlier this year, and until recently it was fine. I replaced with a Wahler. 2. A bad auxiliary water pump - open circuit. So I took one out of my parts car - same thing, d***! Then I disassembled the one from the parts car (since it was already out) Lots of oxidized crud and dirty commutator. Cleaned and reassembled, then it worked fine, drawing about 0.3 amps @ no load. Exchanged the pumps. Works great now, go figure. I know now that the pump isn't that expensive (about $60), but I really had to fix it in one night, and the pump is really simple to take apart. The main reason for this post is to state that it pays to look carefully at the potential causes, because multiple failures just seem to happen with automotive systems. I'm not superstitious, just can't help but noticing how often I've seen this type of thing over the years.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.