Overheating?

RAMROCK

MEMBER
2000 DODGE TRUCK
5.9L
V8
2WD
AUTOMATIC
122,000 MILES

So, my truck starts up and the inside thermostat slowly starts going to almost max temperature and just sits there the entire time I drive it, but then I'll pull over after like 25 minutes of driving it on that supposed heat. I take the radiator cap off and it should explode on me, but it doesn't, it has normal pressure. I also changed the thermostat in the engine and it had a fuck ton of rust and dirt and I cleaned it out and it still says it's running hot, and the radiator isn't just holding water but it isn't losing a lot of water at the same time, so if someone could please help me, I'm starting to think it's either the inside thermostat or a sensor or something.

Thursday, October 19th, 2023 AT 2:18 AM

3 Replies

JACOBANDNICKOLAS

MECHANIC
110,055 POSTS

Hi,

Will the engine overheat if you are driving at highway speeds? Have you flushed the radiator as well as the block? Other than the temperature, are there any drivability concerns?

Let me know. Also, and don't laugh, let me know if the heater is working.

Take care,

Joe

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Thursday, October 19th, 2023 AT 6:08 PM

RAMROCK

MEMBER
2 POSTS

No, it doesn't overheat driving down the highway. I drove it an hour and a half from where I bought it. Also, no I have not flushed the radiator, and the heater works but the A/C does not.

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Thursday, October 19th, 2023 AT 7:06 PM

JACOBANDNICKOLAS

MECHANIC
110,055 POSTS

Hi,

If it doesn't overheat at highway speeds, then there is a problem with the cooling fan. When driving, air flows through the radiator. When you stop, there is no more airflow, so the cooling fan has to draw air through the radiator. If that doesn't happen or not enough is drawn through, the engine will overheat.

When the under-hood temperature gets too hot, you should hear the fan increase in speed. It can actually sound like a jet engine. If you don't hear that, replace the fan clutch.

The fan clutch is mounted to the water pump along with the fan blade. You need a spanner wrench and a large, open-ended wrench to remove it. See pic 1 below. Once you unscrew the clutch/fan assembly from the water pump, remove it, unbolt the fan blade, and install the fan blade to the new clutch assembly and reinstall.

When you do this, the nut can be a bugger to get off. Don't be afraid to wack it with a hammer in the loosening direction a few times to break it loose.

Let me know if this takes care of the problem.

Take care,

Joe

See pics below.

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