How Do You Know Your Thermostat And Water Pump Are Going Out In Your Car

Posted in Cooling Perfomance

What are the warning signs that they are going out?

My temperature is spiking and then going down and not regulating the temperature.

The coolant in my reservoir was low so I added more. I checked it when I got home (about 15 mile drive on highway) and the reservoir was empty.

Is this possibly the water pump and thermostat or something different?

If it helps, the make and model is a 98 chevy lumina.
The temperature has just started spiking today. It has not gone into the red at all. It just been running a lot hotter than usual (past the middle of the temperature gauge). My car automatically dies when the engine overheats to protect itself, but I haven’t let it get to that point.
My radiator was replaced 2-3 years ago. Surely that’s not bad yet. I have never replaced my water pump. We are taking it to a mechanic tomorrow, but would like to have an idea as to what it could be first.

There are 7 Answers for "How Do You Know Your Thermostat And Water Pump Are Going Out In Your Car"

    1. CUP T says:

      coil is connected to the thermostat which can be inexpensive to repair, the larger expense comes when you dont diagnose the problem before you over heat your car, as for coolant when its leaking, and leaks enough without repair the next thing to go would be the thermostat, which does cost more than the coil. the radiator is a tough cookie

    2. dj_lonewolf69 says:

      the water pump has a weep hole on it when bad they typically expell coolant out of it. thermostate is most likely due to be replaced. also test your coolant to make sure it is even still effective. if it hasn’t been flushed in awhile it may have turned acidic

    3. ALLAN J says:

      Water pump. The temp will rise and will run progressivle higher Thermostat. If it sticks open temp will slowly increase to hot/boiling. If stuck closed temp will quickly rise to hot/boiling

    4. dodge man says:

      you need to find the source of the leak on this one first,that may be a big part of the heating problem with it,if its a pressure leak its going to get hot like that ,worse than that though if you keep driving it like this,its going to mess up a good engine,providing it hasn’t done any damage to it yet,good luck hope this helps.

    5. Michael H says:

      You could have a leak in a hose or if you find puddles of water under your car after you have driven it and parked for at least 10 min. you could need a new water pump, you should take it to a mechanic and have them look at it and tell you what the problem is.Could be a bad radiator.

    6. book writer says:

      If your thermostat goes bad it will do 1 of 2 things…1) It will stick shut and not let water go through the motor and keep it cool,and your motor will overheat and steam will come out the over flow line on your car, the car will lose almost all it”s power and won’t hardly go when you give it gas. 2) the thermostat will stick open and your motor will take longer to heat up,this is bad in winter because your heater won’t heat your car very well because the water in your car is cold, and your car won’t run as well, you can tell when you give it gas. Your water pump is different it usually leaks water all the time and it’s hard to keep the correct level of water in your car,or you can see the pulley on the end of the water pump shaft wobbling and it could be making a scraping noise or all three. you will need to replace the thermostat if it is doing either and you will need to replace the water pump if it is doing either. thermostat’s cost about $ 5.00 to $10.00 usually,water pumps cost on an average of about $35.00 depending where you live or you buy rebuilt or new.(there is a core charge, you will get your deposit back when you return the old one.)

    7. Scott H says:

      If your thermostat is stuck open, car will run cooler, since the thermostat is not restricting coolant flow so it doesn’t heat up. If it’s stuck shut, it can cause overheating.

      If the water pump is going bad, you may hear a grinding sound as the bearing wears away, you may see coolant around the pulley, coming from the impeller shaft behind the pulley, or the weep hole in the pump housing itself. Or, it could be a head or intake manifold gasket, radiator hose, heater hose or heater core, but some of these are less likely. Have the shop pressure test the cooling system, it’s a good way to spot leaks.

      My best guess is the thermostat is working, as evidenced by the fluctuating temperature. My money is on the water pump.