So my vehicle ('99 ram van 1500 5.9L) has been having overheating issues. It overheats on idle. I thought I fixed the issue bleeding the coolant, but I guess not.

I just want to be clear, if there was low or no coolant in the system, the vehicle would overheat while driving or idling?

I ask because I feel like I am losing coolant somewhere. When I tried bleeding the system again (running engine with radiator cap off), no coolant bubbled out. Thing is, my vehicle ONLY overheats when idling. I'm going to refill coolant and see what happens.

Some history: I replaced the fan clutch when I first bought the vehicle. This fixed things for a little while.
Replaced water pump, thermostat and lower radiator hose (maybe upper too lol ).
I did a pressure test on the radiator and a hose clamp leaked. Tightened it and everything seemed ok only to have issues come back.
Did the chemical test for head gasket leak at the radiator and everything looked ok. Might do it again.
Not seeing fluid on floor of driveway.
Oil is the right color.

Thanks.

 

Get yourself an Infra-Red temp gun. Run the engine to temp, and then scan the radiator, and see what temps look like. Might be partially clogged.... Also may be a worn water pump simply not moving enough coolant at idle.

 

Thanks. I actually forgot to mention I DID replace the water pump and thermostat as well as lower (maybe upper too) radiator hoses. I'll edit my og post. Maybe it's a bad install or a defective pump, but I DO have low coolant. So I think I am losing coolant somewhere. My thing is, the vehicle runs cool, but overheats when idling. I thought it should run hot if there was little to no coolant in the system.

Another thought is a defective gauge or sending unit? I did see one time the temp spiked to hot and my gauge light turned on only to go back to normal temp a minute or so later. That said, I still have low coolant. Lol.

I'll see about the scan tool. Thanks for that.