Ok, I have been noticing that my truck is running cold, as far as i know normal running temperature is slightly below half on the guage, well it barely gets above the cold line. So i figure my problem is the thermostat, and since i plan to replace all the fluids in the truck (just bought it 2 months ago), i figure i will do the coolant, and thermostat. The truck itself has 238k on it, but the transmission was rebuilt, and engine replaced due to the head gasket recall, and they only have 60k on them(tranny and engine). My question is, do you think that the thermostat is the problem, and since i need to do that anyways, and i have christmas break coming up, so i have time, should i go ahead and replace the timing belt and water pump too? And is there anything else i should do while i have the chance? I have never done this before, but i have the help on my grandpa who is a retired mechanic, and i have air tools, and other tools needed.

 

Hey!

Does your engine feel hot after driving around a bit? I guess your thermostat may be stuck open, but it would seem to me that you would still get a warmer reading than what you are describing. Could be wrong though. Your thermostat is easy to get to, so I probably wouldn't replace the timing belt and water pump and all that stuff unless you decide you want to do that since you will already have your radiator partially drained. Your thermostat is down by where your lower radiator hose goes into your water pump. All you have to do is remove the 3 nuts/bolts holding that elbow peice on. You will see the thermostat just sitting there. Pull it out and replace with your new one (I recomend Toyota brand by the way). Really easy.

Your problem may or may not be your thermostat. Your temp gauge is not connected to the thermostat but to a "coolant temperature sensor" that screws into the "coolant bypass manifold" (I think that is what it was called). This is located behind the intake plenum and is mounted on the intake manifold. There are about 3 or 4 other sensors and stuff plugged into the "coolant bypass manifold." I think the sensor runs about $25 at Toyota. Just something else to think about.

Well, have fun.
Daniel