Heat?... You can't handle the Heat!.. 240d

[bennett]

Just thought I'd give you guys a FYI why we could not get interior cabin heat inside my friends 1980 240d.
Fist off I am the one that couldn't get my motor past 60* C for months until I stumbled on to a Behr Thermostat ( third time was the charmer). Long story short .. my 1981 240 heats right up to spec and have great heat in the cabin now.

Just recently my friends 1980 240d motor was not getting up to heat as well, the cabin would hardly heat at all. Thinking of pulling the heater core was not an option. We put a Behr t-stat in his car which solved the motor temp issue and still no cabin heat. We pulled the hoses off the firewall and did an acid wash/clean to the heater core. I could not believe how much crap came out of that core. We flushed both ways. The gunk that came out reminded me of Olympic Redwood Stain ... rust colored and thick. I'd guess we ran 50 gallons of water through at various pressures until we saw no more colored water. I believe the sediments had built up so high that there was no room left for warm water to conduct to the exchanger. Starting and stopping the water as we flushed seem to verify that it would settle and then a new burst of water would bring it all out again. 45 minutes or more of flushing the core got it clean IMO.
We repeated the same process to the block and radiator with similar success. After nearly an hour of pushing water through we got tremendous amount of sediment out of the system. Rusty looking thick sediment came out each time after intermittent flushing with hose pressure water. We refilled the system with the correct anti-freeze mix and now it heats up to spec quickly.
Anyway for those that are not getting interior heat.. you may want to consider that the heater core is most likely occluded with debris from years of neglect from previous owners. I'm sure a citric acid flush might have done a better job of cleaning but we succeeded in getting our heater problem solved.
Heat.... we can't handle the heat. That car really IS capable of putting out a tremendous amount of heat even on the low fan setting.

Maybe this might help someone else who is heater impaired!!