Car Keeps Overheating

My family has a 2003 Ford Explorer that overheats a lot. We have taken it to 16-17 garages and they cannot find out what’s wrong with it. It overheats when its hot outside, or when we are going up hills. The temperature gauge does not gradually go from C to H It goes straight to H. Then we have to pull over and wait for it cool down, when it finally goes back to C we start to drive again. One time this happened 11 times in 1 day! We put an average of 45,000 miles on this car every year. We need a solution to this problem. Quick!

Any symptoms other than the gauge, like boiling over?
If not it could be a problem with the gauge or temp sensor.

How does the coolant look? Clear or muddy?

It could also be something simple like a radiator cap that’s not holding pressure or a sticky thermostat.
Have these two things been replaced? They’re not expensive.

Try starting the engine from cold with the radiator cap off.
Do bubbles percolate up and smell like exhaust fumes?
If so that indicates a bad head gasket.

You’ve taken it to 16-17 garages and none of them could find out why it was overheating? I’m sorry, but there has to be some mitigating factor that’s not been included in the post. Diagnosing overheating problems is a step-by-step textbook analysis that first checks all the elements involved in dissipating heat and then checks those elements involved in possibly generating excess heat. I’m having a difficult time believeing that 16 different shops could not diagnose this.

elements involved in dissipating heat include

  1. the thermostat
  2. the radiator
  3. the water pump
  4. the radiator hoses
  5. the radiator cap
  6. heater hoses and other potential leak sites
  7. the cooling fan(s)

elements involved in possibly generating too much heat include
a) headgasket breech
b) lean operation
c) advanced ignition timing

Numerous tools are available to do diagnosis, including simple thermometers, infrared pyrometers, flow gages, pressure gages, compression testers, and other tools of the trade. T-stats can be tested with a hotplate, a thermometer, and a pyrex container. Radiators can be “mapped” with a pyrometer. Other tools are used to test other functions.

This is the classic symptoms for a bad radiator cap, except for the sudden jump to hot. When you pull a hill with a bad radiator cap, the temp gauge will rise up quickly, with in 15 seconds or so, but to jump suddenly in one second or less indicates something wrong with the temp sensor or the computer.

Anyway, the radiator cap is cheap so I would recommend that you change it before doing anymore testing and see if the problem persists. Almost all other testing involves removing the radiator cap, so if the cap is the problem, it goes undetected.

I still can’t fathom why among 16 shops not one could diagnose a simple overheatting problem. My gut tells me that something is missing here. I’d feel better if I knew what it was.

Whatever the actual cause of the overheating is/was, I think that there is now a larger issue.
If this engine has really overheated as many times as the OP claims that it has, I think that by now the engine must have warped heads, and/or breached head gaskets, and/or scored cylinders, and/or damaged bearings, and/or…

An engine that overheated “11 times in one day”, plus on numerous other occasions, is now a piece of severely damaged goods. Personally, I doubt if this engine will run much longer due to the damage from repeated overheating incidents.

Before investing any additional money in this engine, I would suggest that the OP have a compression test and a leak-down test performed. If the outcome of those tests is as bad as I envision, rather than “throwing good money after bad”, I think that the OP should be shopping for his/her next vehicle–or at least a new engine for this vehicle .

An excellent suggestion VDC. I concur.