Questions and Answers

Hot Club Wagon Q. Vincent, My wife's van has been overheating under highway driving conditions. For our purposes, I am using the word overheating, but it is probably more appropriate to say that it is running hot. The temperature gauge has never gone into the "red", but has been coming close for the past few weeks. Our spring temperatures are reaching 90 during the day here.

I have done the following:

• Replaced the Radiator cap - factory spec.
• Replaced the Thermostat - factory spec.
• Checked fan belt tension.
• Flushed the cooling system and filled with water (the antifreeze that came out did not appear to have rust or particles that would cause restricted flow).
• Checked for collapsed hoses.
• The radiator was replaced 18 months ago with a new unit.
• Changed the oil to 10w40.
• Checked for seepage from the water pump.
• The fan clutch has some mild resistance when engine is off and cool.

These have made no difference. The overheating occurs gradually when driving for a long period of time (greater than 1/2 hour). The gauge's movement is gradual, there are no significant swings in the temp. It cools down slightly when idling, or driving slowly. I am unsure what to look at next. Do you have any suggestions?

1994 Ford Club Wagon (E150)
5.0L V-8
162,000 miles
Automatic transmission with overdrive
Fuel injection
ABS on front
Power steering, brakes, windows
A/C

Thanks,
Jay

A. Since this is a gradual problem that's developed over a period of time. it may be the cooling passages in the block are starting to close up. When you say you flushed the cooling system, was it a power back flush. What makes a back flush most effective is that it pushes against the normal flow and pushes the junk back and out. Anyone who has a swimming pool knows how effective a back flush is.

If all you did was stick a hose in the radiator and run the engine, all you did was clean the radiator somewhat. I would recommend a power back flush and a 50/50 mix of a good anti-freeze. The water alone could also cause the gradual overheating.

Another possibility is the water pump. The fins that move the coolant through the engine gradually disintegrate over time. It eventually get to the point where it can't pump enough coolant to cool the engine properly. If the water pump has never been changed, I would recommend it, if only to eliminate it as a possibility.

Check the fan clutch. Stand in front of the van with the hood up. Then have someone start the engine and listen. You should hear the fan roar and then gradually the roar will die down to nothing. Now close the hood and let the engine run. Watch the temperature gauge and let it heat up to normal operating temperature. As the temperature rises, you should hear the roar again as the fan clutch engages and stop when it disengages. If you don't hear it, then the fan clutch is probably bad.

Another thing to check is airflow. Make sure the grille is open and there is no junk or garbage blocking the front of the condenser. This is often overlooked and a likely cause of the problem you describe.

The last thing I would suggest is to check the thermostat you put in. Make sure it is not a 195° thermostat. I would not put anything over 180° and in the summer on long trips, a 160° might be better.

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