1980 300TD wagon, 150k, runs like a top, temp guage when running hovers
around 85C and lower when running down the road when the outside temp is
20F. I verified that the vacuum line connected to the coolant valve
diaphragm operates the diaphragm and the valve, but no matter what
position that coolant valve is in, no heat. Here's a clue: the vehicle
spent 23 years in Florida. No nead for heat down there...
I have several theories:
1) There is a flap open somewhere letting in a large amount of outside air.
2) The coolant valve is broken, corroded, and though it moves easily
with fingers or vaccum via diaphragm, it's not letting hot coolant into
3) Since I can put my hand on the lower radiator hose at full running
temperature and it's not even warm, my thought is a bad thermostat.
What is the regular operating temp of these 300 diesels? Seems like it
ought to be around 90-100C. I've put cardboard in front of the radiator
but haven't had time to see if that helps on a long enough trip, it's
only 7 miles to work.
4) The "amplifier", whatever that is, isn't working.
5) All the insulation is torn off the underside of the hood. I wondered
about using contact cement to attach a layer of Reflectix
www.reflectixinc.com from the hardware store to keep heat in the engine
bay, allowing the motor to reach operating temp.
Our 2001 VW TDI provides heat like hell...what am I missing?