false overheat

Ford recommends flushing the system and replacing the antifreeze every 5 years. Maybe the rust inhibitors have broken down and the suggestion about a sticking thermostat is correct???

Pirate wrote:
Interesting that his 2006 only now is having an issue. I would think that if it was false overheat per the TSB, it would have surfaced by now. Perhaps something else is wrong.

Yeah, my thought too.

Chum lee

I have only owned it for a little over a year

Interesting that his 2006 only now is having an issue. I would think that if it was false overheat per the TSB, it would have surfaced by now. Perhaps something else is wrong.

FarmerBob wrote:
The "overheat" occurred while idling after a 5 hr drive. Went into limp mode. Shut off engine and re started and it was fine other than engine check light. Scan said code p1299 and that the temp got to 253.

If you have your VIN number you can check with most Ford dealers to see if the TSB mentioned above has previously been done to your vehicle. Because of the vehicle age and the time between the TSB issue and today's date, Ford may deny the warranty issue if it has not been previously completed. The parts may still be available for purchase though.

Chum lee

I think Pirate has the right answer. There's a good probably some conditions may trap air in your crossover pipe preventing the T-stat form opening, and hence the updated crossover.

With a 16 lb. cap the top temp would be 158F.

The "overheat" occurred while idling after a 5 hr drive. Went into limp mode. Shut off engine and re started and it was fine other than engine check light. Scan said code p1299 and that the temp got to 253.

Assuming the coolant level is full, since the overheat occurred at idle, I would check the fan clutch before I dived into the cooling system. (easy to do) Does the engine cool down when you are moving at say 30 mph, or, does the overheat occur at all speeds? With the engine shut off and your hand on the fan, there shouldn't be any forward and/or reverse play (wobble) between the radiator fan and the fan clutch. If the overheat occurs at all speeds its probably not the fan clutch and I would then also look at the thermostat as others have mentioned.

It's not common on Ford V10's but if you have air trapped in the cooling system around the temperature sensor, (or low coolant) you will get a false high temp reading. You didn't say where you pointed your scan gauge to get your temp reading. Always use a 50/50 coolant/water mix.

Chum lee

could be a faulty temp sensor, using a scan tool read the engine temp, and a infrared thermometer check the upper rad hose and compare readings and see where that goes