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+--- Thread: Coolant temp sensors (/showthread.php?tid=295)
Coolant temp sensors - Gasoline Fumes - 03-28-2009
What do the four sensors do on my '85 300D? I see two on the head between the GPs and two in the thermostat housing.
RE: Coolant temp sensors - ForcedInduction - 03-28-2009
Head: Cluster gauge, glowplug relay
T-Stat: Heater lockout and EGR computer input.
RE: Coolant temp sensors - Gasoline Fumes - 03-28-2009
Thanks!
What does the heater lockout do?
RE: Coolant temp sensors - ForcedInduction - 03-28-2009
It prevents the occupants from being blasted with cold air. The switch closes when the engine gets above 40*C.
RE: Coolant temp sensors - Gasoline Fumes - 03-29-2009
Good to know, thanks.
RE: Coolant temp sensors - Gasoline Fumes - 03-31-2009
Now that I've got the sensors sorted out, it's time to put some of my new knowledge to work. I'm trying to fix a couple of issues on my neighbor's '84 300D. I'm not sure if the two are related or not.
1. Temp gauge isn't working. It happened at least once before, but fixed itself. It seems permanently dead this time. Sender is about 764 ohms cold and 98 ohms hot. I tried grounding the sender wire and turning the key on, no response from the gauge. Is the sender connected directly to the gauge?
2. Low heat output. Engine gets hot, heat exchangers (WVO blending) in parallel with heater core get hot. Heater hoses are only warm. What is the default position of the monovalve? Anything else that can limit heater flow? I have a valve in the heat exchanger circuit and closing it has no effect.
I believe the engine is getting up to operating temp.