2003 explorer 4.6L 218,000mi overheating

[yarrylo]

Overheated and found the cap on the coolant expansion tank off - I guess I had left it off unless it blew off from the pressure. So I refilled the system and continued to overheat. I found that I was not getting heat in the car, so I changed the thermostat. Now heat works but when I watch the ECT (engine coolant temperature)on the OBDII it is going up to 250F + before I turned the motor off. The temperature gauge on the dash stays right in the middle between H and C. Is this engine in the process of overheating ? In any case how damaging is it to run it like this so long as the dashboard temperature gauge doesn't move from the middle?

 

[silverfox103]

Did you bleed the air out of the cooling system?

Tom

 

[Joe in NY]

You have to rev to engine up to 1,500 ~ 2,000 rpm from stone cold to hot with heater on full and pressure cap off. This allows the air to be purged.

But yes, 250* is overheating.

Remember, these are Ford gauges for idiots. If it is not boiling over then it is NORMAL, if it is boiling over and ruining the engine, then it is HOT. No in between.

Ford gauges are the worst, only show you the bad after it has already happened.

 

[J. Gehret]

Sounds like you have an air pocket. I recently had a similar stupid problem with my 03. Engine would run between 195-205 using a thermal gun. Scan tool showed coolant temp at 230+. Keep in mind there is no temp sensor for the coolant. Just a cylinder head temp sensor. Stupid design at best.

 

[Joe in NY]

There actually is a temp sensor right in the intake manifold..

 

[plasticseng]

I have always had luck pulling the thermostat housing and thermostat and filling from there. Fill it all the way up so that the thermostat is practically submerged when you put it back in. This will assure that the thermostat gets heated and opens when it is supposed to. Of course, fill your coolant tank and radiator also.

 

[yarrylo]

Thanks for the help. I had bled the system before, but I did it twice more this morning but still getting coolant temps 230F+ with outside temp about 87F. Heater is working. Any idea what the maximum allowable coolant temperature should be about.(say when climbing a hill with the a/c on during a hot day)?

Some background: I've had a slow leak in my coolant system for the past couple of years and so every 2 weeks or so I add a quart or so to the system. During the summer, I have just been adding tap water, and so at this point it is 100% tap water in my system. The radiator and water pump have never been changed out. I checked the seep hole on the water pump and don't see any sign of leakage from there.

The fan is running whenever I check. I see no obstructions around the fan.

So I suppose I should get a compression check on the coolant system to try to localize the leak. Also makes me wonder if there could be enough deposits from the tap water in the radiator (or even the block) to have affected heat exchange or water flow. Makes me wonder whether I should change out the radiator or even the water pump as kind of a last ditch effort..

 

[silverfox103]

If you have just tap water in the cooling system, that's definitely part of your problem. Also with 218K, your cooling system needs to be gone through; fix leaks, have the radiator boiled out, probably the thermostat and radiator.

Tom