Warm up issue, leaning towards thermostat

[teler86]

Couple days ago I noticed that my car was not warming up on my ride back from night school, the oil temp had risen before the coolant temp. Half way home the car finally warmed up, but as I continued to drive on the highway the temperature dropped back down again. I have not had time to investigate this but, to me it seems like a thermostat issue. The part that throws me off is that it had never done this before, and only started when it got cold outside. I have read that you might as well do a timing belt if you are changing the thermostat, while it is almost time for me to do one, I was hoping to wait until the spring when it gets warmer to do the belt. Has anyone changed the thermostat without doing the timing belt, and how long did it take you, also if you guys dont think its the termostat let me know.
Thanks-
Roman

[s42k5b]

Yeah if you are close to needing a tbelt def worth it to do one while you are in ther. Water pump should be done also at this time. I had mine done last week w/out replacing the tbelt, took about 3 hours..

[teler86]

how long does a t-belt job typically take to do at home?
-Roman

[Bimmer2Audi]

Try the coolant temp sensor. My car ran the same way until I swapped the sensor.

[teler86]

changed the coolant temp sensor and all is well, minus me being pissed off lol. It was somehow lodged/rusted in there, I assume it was the orignal sensor since the o-ring was pretty much rotted 1/2 away, and the amount of force i had to yank it out with, ended up ripping the wires out of the harness trying to pull on them, and had to re-pin the damn thing. Good thing I have a buddy with a 2.7t around here, so I could compare the wiring. well at least I fixed it.
-Roman