I have a d16y7 with a 4-speed automatic, and it will not reach operating temperature. I can let it idle for 30 mins, or drive 70+ for over and hour, and it barely comes off of C. Originally the radiator fan was constantly on, I replaced the sensor for the fan, and now it turns on only when hot, but it rarely gets hot. I have replaced the thermostat 3 times, bled coolant correctly multiple times, no coolant leaks, I'm at a loss here. Any outdoor temps of 40F or lower and I have no heat, no "overdrive" or my last gear, and with the temps in the negatives lately it's miserable to drive this thing. Any advice would help as this is my daily.

 

coolant may be getting past the thermostat, check the face of the thermostat housing. if it has corrosion, clean it smooth. Did you recently buy the car or change the hoses? If so, check to make sure the hoses are routed properly. Block off part of the radiator and see if the temp comes up, if it warms up then I would run it like that until the weather gets better

 

I've had the car and for about 4 1/2 years now, hoses and everything are where they should be. I was debating putting cardboard in front of half my radiator and testing that method. Last time I changed the thermostat it has slight corrosion on it but i cleaned the housing, replaced, and flushed the coolant system. Myonly other thought is maybe I need a hotter thermostat? I believe I have a 170-degrees thermostat in now.

 

did you replace the rubber gasket thing that goes around the thermostat?

 

[QUOTE=youstolemybeer;53029173]did you replace the rubber gasket thing that goes around the thermostat?[/QUOTE
Yes, the new one came with a new gasket around the edge.

 

did you do ANY changes/repairs immediately before it started acting up?

 

Sure sounds like a thermostat stuck open. Like, couldn't really be much else.

Stock thermostats are fully open ~170F. I can't imagine a reason you'd want to raise that. Maybe it is worth trying to make some sort of blocker for the front?