240D never reaches operating temperature
 

This is a 83 240D with a GreaseCar conversion. I have coolant hose teed off at the firewall and extended back to the trunk.

Haven't driven the car much yet but I just drove for a good 20 minutes today and my temp gauge never got past 1/4th mark
Do I need to replace a stuck open thermostat or is this some problem with the GreaseCar system?



Also, If I'm replacing the thermostat I suppose I should replace the coolant. What's the official word on the right coolant to use?




TIA

Replace the temperature sensor while you are at it.

Everyone swears by Mercedes Benz original coolant, but you know, I found out Sierra is Polypropylene Glycol and should be fine with all plastics! Veggie oil burners seem to run a bit colder though but I'm not sure about 1/4th of the gauge.:confused:

Are these known to fail? 25 bucks for the replacement








What I'm trying to get at though, is it possible for the shear length of the coolant line to essentially act as a cooler and even though the t-stat may be closed, the coolant isn't getting hot enough?

Yeah! When you think about it it's more than twenty years old!:D

They don't usually outright fail but age and thermal cycling fatigue will cause them to read much lower than the actual temperature.

No, 10' of coolant hose is not enough to dissipate that much heat.