driveslow

car is a 94 civic ex stock.

I have just recently replace timing belt, water bump, radiator and hoses. I have bleed the cooling system completely which took me about 50 minutes to complete. I notice that in the morning with the outside temp of around 50 -60 degrees. My temp gauge stays at a cold for almost 15 minutes of driving. Heater setting hot BUT NOT ON. 15-20 minutes of more driving its slightly below the normal operating temp. This only happens in the morning. When leaving work around 3pm and the outside temp around 70-80, the temp gauge looks pretty normal where it is just right below the middle mark. I have a couple theories but I dont want to cloud your guys opinion. What do you guys think this is.

instructor74

the tstat has failed. It is stuck open and when its cold out the coolant isn't able to heat up

driveslow

but wouldnt things start working again after the engine heat warms up the tstat? the engine bay way past 70-80 degrees which happens within minutes? keep in mind its only 50-60 in the morning here in TX.

ekb16

iTrader: (1)

change out ur tstat and see if that fixes ur problem...my car had the same issue, i would let it warm up while idling and once i start drivin the temp gauge will slowly creep down to about 1/4

driveslow

while digging thru some threads, i ran into someone that stated that there are tstat that are made for winter and for summer. Is this true. do you think an auto zone tstat would do the trick?

driveslow

anyone else care to chime in? I am about to go to honda and pull the trigger on new tstat and gasket. just want to make sure its not a sensor or something else.

driveslow

update

Just swapped it out. I guess well find out tomorrow morning if it worked or not. btw, the original tstat rubber center nipple appeared dried out and cracked even though it is constantly submerged in coolant. based on the look of the original, it was the tstat. more updates tomorrow.

driveslow

This morning at was at normal operating temp within 5-6 minutes. Thanks all!!