Nissan Repair: nissan sentra 01, nissan sentra, petcock

Question
i wanted to change my thermostat in my car because it always overheats (to the 3/4 mark). i heard to drain the engine and the radiator a couple of times. but i don't even know how to do that. and then with what do i fill what back up?? please help me out! thanks

Answer
Hi Jason -

Just to double check to see if your thermostat is stuck - when the car has been running for a while (I say about 15 minutes), feel the top hose as compared to the bottom hose. If the top is hot and bottom is not, then your thermostat does need changing. If both hoses are hot, then it is something else that is overheating the car.

To drain your cooling system, the drain petcock is on the bottom of your radiator. Look for a plastic wing nut when looking under your vehicle.

However, when I change thermostats, I do not drain. I simply remove the housing, replace the thermostat, and chenge the oring or gasket for the outlet. Replace with a 50/50 mix of water to antifreeze. Fill the radiator to the top and run the engine until you see water circulating, top it off, and you are good to go.

If your car is overheating, ensure that your cooling fan(s) work. That could be another reason. If the fans do not sork, get back to me and I will go through a diagnosis with you, because it gets a bit involved.

Hope this helps -
aloha
Calvin