2002 Mercury Cougar temp gauge shows overheating but no fluid loss

Tiny
REET43
  • MEMBER
  • 2002 MERCURY COUGAR
  • 2.5L
  • 6 CYL
  • FWD
  • MANUAL
  • 76,000 MILES
I bought this car brand new in 2002. It only has 76,000 miles on it. In November of 2013, the temp gauge climbed rapidly in a pharmacy drive thru that I had just pulled into. I turned it off, let it cool down for about 45 minutes, and then drove it on home, about 1 mile. Since then, the water pump, water pump belt, radiator, heater core, thermostat, sensors, alternator and battery have all been replaced. At one point, when the hoses were taken off, we found a little black piece of plastic (like the safety seal on a bottle) came out, and once a tiny, tiny black rubber ring, looked kind of like a gasket, came out. Bought a test kit for the head gasket, even though it had never showed any 'classic' signs of it being bad (white smoke, water from the tailpipe). The test was negative on the head gasket. The fluid level has never dropped at all. We marked it on the tank. There have been a few air bubbles come out, but nothing more than that. I am a single, disabled mom, and I desperately need my car back! I've been without a car now since November of 2013, and need my vehicle running again! Please help!
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Wednesday, March 4th, 2015 AT 12:47 PM

4 Replies

Tiny
CARADIODOC
  • EXPERT
Your car uses an electric radiator fan. Have you checked if that is turning on when the engine gets hot?
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Wednesday, March 4th, 2015 AT 2:11 PM
Tiny
REET43
  • MEMBER
Yes it actually has two fans a low-speed and a high-speed. I can hear the fan on when its running and when its running hot. The high speed fan is louder and that's what I seem to be hearing.
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Wednesday, March 4th, 2015 AT 2:34 PM
Tiny
CARADIODOC
  • EXPERT
The first thing that comes to mind is the head gasket test. Did you use a glass cylinder with two chambers partially-filled with a special dark blue liquid? If so, that liquid is rendered useless if it freezes or if it gets contaminated with antifreeze. Once either of those occurs, it will never change to bright yellow. In fact, this is why the auto parts stores that borrow tools will have this tester but they make each customer buy their own bottle of fluid.

Water dripping from the muffler's drain hole or the tail pipe is a sign the exhaust system is working properly. White smoke is not. Regardless, it is very uncommon to have a leaking head gasket if you don't also have a gradual loss of coolant.

When the overheating occurs, feel the upper radiator hose. It should be too hot to hold onto for very long. If it's just warm, or cold, the coolant isn't circulating. First, look on the thermostat housing for a bleeder screw to let the air out. Air will collect under the thermostat when the system is being refilled, and that will prevent it from opening. Thermostats have to be hit with hot liquid to open. Hot air won't do it. If there's no bleeder screw, look for a sensor or threaded plug that can be removed while the cooling system is being filled. If you remove a sensor, leave the ignition switch off when it's unplugged to avoid setting a false diagnostic fault code.

If the upper radiator hose is hot, I know this sounds stupid, but check that the radiator fan is blowing the right way. If the wires are reversed, it will blow air forward against normal flow when driving. That is caused by switching the wires when a fan is replaced.

Also look for a butterfly collection in front of the AC condenser. That will block air flow through the radiator.

There's one more thing I've seen happen that can cause overheating after a new radiator was installed. The old one had badly-corroded cooling fins so the radiator couldn't give up its heat. The new one came with protective plastic caps on the tubes to keep debris out. Those caps got painted when the radiator was painted, and the mechanic didn't see them or remove them during the installation. The solution to the original problem was a new radiator, but the apparent problem was still there due to those caps.
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Wednesday, March 4th, 2015 AT 3:11 PM
Tiny
REET43
  • MEMBER
I forwarded this info to my son in law who has been working on the car. And waiting on a response from him. Will get back with you shortly. Thank you for your help. Hopefully one of these things will fix it.
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Wednesday, March 4th, 2015 AT 3:50 PM

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