Hi guys,


I have a 2003 that has suddenly decided to start getting hot and gauge going into red when pulling over 60, even empty trailer. Going up a pass with a load it gets hot. But gauge goes up almost to red or into red and then comes right down if you slow down. Checked coolant, air filter. But maybe just gauge issue? I already know I have issues with my gauges. If wasn't really getting hot how would I tell?

Thanks for any help!!

 

Just a guess but it could be an issue with the radiator fan.
Is it fine with no trailer?

 

I'm with B.Lee's thoughts on your fan first, but there are other things to check.

1. When the engine reaches a certain temperature, the ECM sends a signal to engage the fan. When engaged, you should hear a 'roar' from the engine. You should hear it when you are driving, it is fairly loud. You may have noticed it in the past. Do you hear it now when overheating?
2. Check the wire harness that goes to the viscous fan drive. Many folks have reported this harness cut by the fan. If cut, repair and zip tie them out of the way of the fan. This normally throws a code but you didn't mention any check engine light.
3. With a cold, non-running engine, reach in there with your hand and spin the fan. If it spins freely without drag, more than 5 turns, replace the viscous fan drive.
4. How many miles on the thermostat and coolant? My '03 had the original thermostat when I sold it at 295k miles. Coolant is supposed to changed every 100k miles. If it is the original thermostat, I'd change it out if #1 and 2 above are ok.
5. Have you done any work on the engine just before this started?
6. I would pick up an IR Thermometer (pretty cheap tool) and when the gauge is in the red, pull over and take temps of the thermostat housing, radiator hoses, etc.
7. Speaking of radiator hoses, check the condition of them. If the hose is worn out it may start to collapse and restrict the flow of coolant. Replace as needed. Be careful to properly burp the coolant system to get rid of any air bubbles.

BTW, an IR thermometer is also good for checking tire temperatures when on your trips. When you pull over for fuel, stretch, or food, shoot the tires with the thermometer. If you find one that is a lot hotter than the others, it is usually indicative of low tire pressure caused by a slow leak. If you catch the slow leaker in time, you can take care of it before it blows as you go down the highway. This is easier/cleaner than checking tire pressure with a pressure gauge.
Back to morning brew . . .