Mercury Repair Questions? Ask a Mechanic for Answers ASAP
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Hello, when it goes to overheat is it actually running hot if you check the engine temperature or does the gauge just peg. Do you hear the fan clutch lock and roar loudly as it runs hot? Do you have good heater operation?
Ok it could be caused by an air pocket near the coolant temperature sensor but i f you have good heat all the time then the system should not have air in it. There should be about 10 degrees difference with the upper hose hotter and the lower hose cooler. Since the radiator is new and the thermostat is new. For it to overheat with a load on of the ac but its not running hot could point to a defective temp sensor or issue with the instrument cluster itself. you would need to look at the actual temperature sensor input using a scan tool when it runs hot to see if the sensor is showing its overheating or pointing to a problem with the gauge itself which is part of the cluster.
On the 4.6 its a cylinder head temperature sensor, so I would shoot the area where it sits and see if the temp matches whatthe sensor is reading, if not replace the sensor and retest. The wiring to the sensor is a common spot of animals to nest and chew up the harness as well. So inspect the wiring for damage and repair as needed.
On the rear of the right head and yes the intake must be removed
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Very good, thank you.
Very good and thank you for the update, it sounded more like an air pocket and when it has a lack of heat it is a good indication of that being the case.