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i have a 2000 SE 2.0 and it is indicating overheating at highway speeds. i have replaced the coolant and the thermo stat and it is still happening. at city speeds it doesnt' overheat. the fans are coming on and the upper hose is not hot but warm and the lower is luke warm. any help is awesome.
thanks
 

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DTC P0606
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Hmmm... odd behaviour because it's the opposite of what should happen with a cooling system fault.
First question: The engine is indicating an overheating condition at highway speeds. Is it really overheating? Could be a faulty temperature sensor.
 

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As BC mentioned, it's time to use the "odo trick" (sticky) to see what the gauge SAYS is going on in numbers, & compare that to an actual thermometer (kitchen or infrared) to see what temps the engine is actually at...

These current engines use a cyl. head temp sensor, that does NOT know what temp the coolant is at... Air pockets(hoses blocked or mis-routed), lack of circulation (water pump) etc.. Any leakage from the water pump area? Serpentine OK?

Check easy & cheap first (sensor) B4 guessing an unusual like bad water pump vanes...

ONLY seen that once, and that was reported here on a different Ford model... MUCH older than yours.... Bearings & seals go first normally....

Fans shouldn't work too often, so it seems the engine thinks it's warmer than it is - UNLESS the system isn't bleeding itself right causing an air pocket with attendant local heating & lack of circulation....

Luck!
 

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To observe the information that the sensor is giving the computer use the electronic odometer test mode trick to see if the temp information makes sense. You'll have to familiarize yourself with temps in C, but that won't take too long.

To get into odometer test mode: Key off, press and hold the trip reset button, turn key ON, wait for the gauges to jump and odometer readout to change to [test], then release the trip reset button. Now each time you press and release the odo reset button you will scroll through one of 30 test modes. You're looking for one that reads [15 C] or whatever your ambient temp, or what makes sense that it's your car's engine temp at the time. 15C, for example, is around 60F. The thermostat opens around 94C, and the engine temp should hover right under 100C. If the thermostat is working then you'll see the temps drop after the first time you run into that temp. Now if your temp sensor isn't working correctly you might see some crazy temp jumps like 95C to 200C which would be close to 400F- way hotter than any coolant should ever get. In that case, I'd assume the temp sensor was bad. Even if it showed 150C which is around 300F- that's still much hotter than rubber parts can handle and it doesn't seem possible that the engine could actually be running that hot without something being damaged immediately.

In the future, please give us your engine type, SOHC or DOHC, mileage, transmission, and as much information about the vehicle as possible
 

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To observe the information that the sensor is giving the computer use the electronic odometer test mode trick to see if the temp information makes sense. You'll have to familiarize yourself with temps in C, but that won't take too long.

To get into odometer test mode: Key off, press and hold the trip reset button, turn key ON, wait for the gauges to jump and odometer readout to change to [test], then release the trip reset button. Now each time you press and release the odo reset button you will scroll through one of 30 test modes. You're looking for one that reads [15 C] or whatever your ambient temp, or what makes sense that it's your car's engine temp at the time. 15C, for example, is around 60F. The thermostat opens around 94C, and the engine temp should hover right under 100C. If the thermostat is working then you'll see the temps drop after the first time you run into that temp. Now if your temp sensor isn't working correctly you might see some crazy temp jumps like 95C to 200C which would be close to 400F- way hotter than any coolant should ever get. In that case, I'd assume the temp sensor was bad. Even if it showed 150C which is around 300F- that's still much hotter than rubber parts can handle and it doesn't seem possible that the engine could actually be running that hot without something being damaged immediately.

In the future, please give us your engine type, SOHC or DOHC, mileage, transmission, and as much information about the vehicle as possible
This is a problem I am dealing with. Same thing, replaced thermostat, flushed system, checked hoses. The coolant is flowing, getting plenty of heat from climate control. I did find out that my low speed fan resister is pooched, so will replace that and see where it gets me. But I'm a little pessimistic about that actually fixing my overheating on the highway problem as it seems to me that the fans would become moot givin the air flow past the rad at highway speeds.
 

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Yes - it may help to know if your engine is a SPI or Zetec.

SPI, SOHC, VIN 'P' = coolant temp sensor (also has shrader valve on fuel rail)

Zetec, DOHC, VIN '3' = cylinder head temp sensor (no shrader valve)
 

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oooh, I had the EXACT same problem...let me help. take out the resistor (from in between the fans) disconnect the adapter...it's probably fried/melted and you will need that as well. if if the fans still dont come on after about 10 mins of idling then check out R9/R10 relays located in the fuse box under the hood by the driver's side...I replaced them both and now I am driving around w/o over heating temps. check you spark plugs as well as when this happened I fried my spark plugs 3 times before I figured this out...If you think this cant be THE problem for your over heating you are wrong. easy fixes....about $75 shipped for the resistor and pigtail adapter and about $40 for the 2 relays...piece of mind knowing you wont get stuck somewhere......priceless.
 

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This is a problem I am dealing with. Same thing, replaced thermostat, flushed system, checked hoses. The coolant is flowing, getting plenty of heat from climate control. I did find out that my low speed fan resister is pooched, so will replace that and see where it gets me. But I'm a little pessimistic about that actually fixing my overheating on the highway problem as it seems to me that the fans would become moot givin the air flow past the rad at highway speeds.
Ok, check that..... I said I was getting plenty of heat in the car from climate control. I found out today that isn't "exactly" true. While idleing today I felt a titch chilly, so switched the vents to "floor/cabin" (I usually just keep the setting on the floor), in doing so I realized that there really wasn't that much heat coming out. I revved the engine just a bit for a few seconds and the heat started coming out much better. It was fine for about 3 mins then went cool again. Repeated with same result. Could this be connected to my overheating issue?
 

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@Phreez, I am having a similar problem with the no heat at low rpms, and then good heat when accellerating. I have a thread going already.
Please let me know if you get any info to remedy your problem and I will do the same.
 

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@Phreez, I am having a similar problem with the no heat at low rpms, and then good heat when accellerating. I have a thread going already.
Please let me know if you get any info to remedy your problem and I will do the same.
Ok, I just read thru your thread. Here's what I can input on this. I am prepared to blame this on the thermostat. I have been having a problem overheating so I flushed the system and installed a new t-stat. The old t-stat was 92c, the new one is 95c. The old was OEM, the new is aftermarket.The heat in the cabin problem didnt' start till the new t-stat was installed. I'm not ready to blame the opening temp of the t-stat but rather I believe I may have either a faulty one or as is mentioned in your thread, one that opens too far and allows too much flow.
Ill change it out for a better one and report back what I find.
 

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Ok, I've swapped out the t-stat that I put in saturday. Went to Ford and got an OEM. Temp rated at 92. Still not getting proper heat. Next step is using a hose to try and flush out the heater core. I've heard mixed reviews on this method, some say it worked some say nope.
 

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OEM stat should be 192*F or 88*C. I flushed alot of crap out of my heater core a few months ago.
Drain coolant
I pulled the t-stat housing and left it setting off to the side.
Removed one of the HC hoses from near the pump and hooked up a garden hose about medium pressure.
Flush til you see clear water coming out the housing.
 

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OEM stat should be 192*F or 88*C. I flushed alot of crap out of my heater core a few months ago.
Drain coolant
I pulled the t-stat housing and left it setting off to the side.
Removed one of the HC hoses from near the pump and hooked up a garden hose about medium pressure.
Flush til you see clear water coming out the housing.
That is what I will do.... here's hoping [cool]
 

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Ok, I have heat [headbang] After reading thru counless threads on this issue I noticed one or two small little reply's suggesting to run the engine and massage some of the hoses. This being done to flush thru any air pockets in the cooling system that might have gathered after a fluid change.
This I did, and it seems to have worked. I have very good heat while idle now.

FC
 
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