Dodge Ram is Running Hotter Than Normal

engine overheating
Running hot or overheating engines should be fixed, and soon!. Getty

We get a lot of questions about overheating. Everyone has a theory, and most of them are correct in some situations. That's whey we get so many questions! This one came in from the owner of a Dodge Ram 1500 in North Carolina and typifies the running hot or overheating problem and how hard to mail down it can be. Some things to consider below.

Question:

A little background first:

  • 1996 Dodge Ram 1500 SLT
  • 5.9 liter Fuel Injected V-8
  • Automatic transmission.
  • 161,000 miles
  • ABS Brakes
  • P/S, A/C, Cruise Control

I first noticed the truck was running hotter than normal about a week before Memorial Day, I assumed it was low on coolant. I was away the following week, and arrived back home the Thursday prior to Memorial Day. Friday, we had plans on going to the beach for the weekend, I pull a pop-up camper with the truck.

I packed up the truck, attached the camper, and remembering that the coolant may be low, topped it off in the radiator. After a few miles down the road, I noticed the temperature reading on the gauge rising above the normal operating temperature, normally 200°.

I stopped at a nearby Firestone dealership and had them put a pressure test on the system. They said I was losing pressure from someplace, although there was no visible leaks and the oil looks normal. I limped the truck back home and parked it.

I flushed the system yesterday and started looking for leaks again. Again, I couldn't spot any visible leakage from the block, the thermostat appears to be working properly, and the oil appears normal. The truck is now maintaining a 250° operating temperature.

When I rev the engine, the temperature gauge moves slowly back to the 200° range, but when left to idle, it moves back up to 250°.

It doesn't move past that point, I was concerned that it would eventually move to the red line and overheat. After idling more than 30 minutes, it did not.

I've had the water pump replaced about 8 months ago. I'm just curious as to what you think the problem could be. I'm not ruling out anything, I'd just like to know a little before sending the truck to the Dodge dealership for repair.

Thanks for your time.
Sincerely,
Bruce
Linden, North Carolina

Answer

According to Chrysler, this is what they consider normal under certain conditions.

The thermostat may be a problem. Most of the time they stick opened or closed. But they often get stuck in positions between opened and closed. So I think the best first step is to just replace the thermostat. This way we will know it is good and you can knock it off the list of potential culprits.

Another possibility is a weak fan clutch. Let the engine run with the hood closed. Then listen to the fan. When first started you should hear a slight roar that will quickly fade to quiet. This roar is the fan clutch engaging the fan and the sound of the fan pulling air. Then when the engine gets to above normal operating temperature, you should hear it start to roar again until the temperature lowers.

This is the clutch operating normally.

Another way to check the clutch fan: disconnect the bimetal spring and rotate 90 degrees counter clockwise. This disables the temperature-controlled, free-wheeling feature and the clutch performs like a conventional fan. If this cures the overheating condition, replace the clutch fan.