Engine Cooling problem
1997 Nissan Altima 4 cyl Automatic 165000 miles
My car had been over heating. I saw that the water pump was leaking. I took the car to a mechanic shop and they told me that the water pump was bad and got it replaced. My car still overheats. What do you think is wrong with the car now? I was thinking that it must be the thermostat. If you have a bad thermostat, will the water still pump the antifreeze?
I am surprised that the shop didn't advise you to replace the thermostat since they are already working on the water (really close to one another).
To answer your question, faulty thermostat does not control the operations of the water pump. For as long as the engine is running and the serpentine belt is attached, the water pump will continue running and will not circulate the coolant kin the thermostat is stuck closed.
There are several reasons why a vehicle overheats.
1. Faulty thermostat.
2. Faulty coolant temp sensor.
3. Radiator fans not working.
Answer these questions.
Does it overheat all the time, or some of the times? If so when? At idle, at the stop light, while you are driving. What speed.
What you notice it overheating, do the radiator fans turn on? Do you have enough coolant? If you turn the fan control to maximum and temp control (on the dash) to full heat, does that help lower the engine temp gauge in the instrument cluster?
March, 17, 2009 AT 8:38 AM
The car Overheats all of the time. The fan does turn so I know that is working, but it doesnt seem to be enough to keep the engine cool. The car is also rough at idle. What happens when a thermostat is removed from the engine and the car is being ran without a thermostat?
March, 17, 2009 AT 8:12 PM
You can run the car without a thermostat, but I won't recommend it. Rather than doing that, just replace it with a new one. It only costs less than $10 and 3 10mm bolts to undo to remove the thermostat housing.
You may want to consider to have the engine pressure-tested to make sure that you don't have any internal leak that can cause the overheating and rough idle.
March, 18, 2009 AT 9:44 AM
So what happens if the engine has an internal leak? In that case what would I need to do? The repair shop where they installed the new waterpump, mentioned that the valve cover gasket was in poor conditions, and that if they pressure test the engine, the inspection plug might have to be replaced. And they also said that they would charge me $150 to replace the inspection plug. I dont want to go back to that place, they dont seem honest. So if I replace the thermostat and it is still overheating, what would the problem be? If it is an internal leak, can I fix that myself?
March, 18, 2009 AT 11:42 PM
I would try the thermostat. Like I said $10 and 3 bolts. Maybe 20 minutes.
Internal leak means bad head gasket and will have to be replaced. Top half of the motor has to come out. You can do it with a friend's help (not just anyone, someone who knows about engine), and a repair manual and proper tools.
But seriously speaking, repairing head gasket is not a simple job. If you have never done one, your helper has to be someone that has done.
But pressure test should be performed before any work is to be done. If you feel you can't trust the shop, you should ask your friends and family for a shop or maybe a backyard mechanic that they use.
March, 19, 2009 AT 3:09 PM
Well I did as you guys recommended and replaced the thermostat. The Engine still overheats. After 30 mins of running the engine, whenever I set it on Drive or Reverse, the Engine makes a repeatedly clacking noise and it turns off while running. I have to wait for the engine to cool again to turn it back on. If I try turning it on, right after it turned off, it will not start. What does that mean, I also notice water coming out of the muffler, but it didnt look like antifreeze, just plain water. What am I dealing with here?
March, 19, 2009 AT 7:58 PM
Water out of the muffler is OK. That is just evaporation from the engine. But you really need to have the engine pressure tested. That is the next step.