Join Date: Sep 2014
Location: Gulf Breeze, FL
Vehicle: 1998 Durango SLT+ 5.9L
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'98 5.9 Getting Hot
Recently I've noticed an issue with the truck getting hotter than usual, even in Spring time temps with the AC running.
I'd noticed my overflow bottle was dry, so I topped it back off and refilled the radiator which had dropped somewhat in coolant levels. It occurred to me that my radiator cap has been failing to hold pressure, so hot coolant was forcing its way into the overflow tank where it would effectively flash boil away (you could hear intense boil/bubbling in the tank after shutting the vehicle off).
Replaced the cap yesterday with one purchased from a local dealer, no more issues with bubbling expansion tanks, but the truck is still running hot sitting in the direct sun with AC on. Highest temps I saw with the TorquePro App was around 233°F, temps would drop if I pulled into the shade and shut the AC off; temps would further drop if I turned on the heat and allowed the coolant to pass through and lose some heat through the blower motor. I didn't get a chance to go for an extended drive to see if temps would return to normal while on the move, as recent construction has turned the streets around where I live into an almost constant gridlock, meaning the truck would be sitting in stop-and-go and getting toasty.
I know the 98-99 models were known to run hotter, and this contributed to an improvement in the fan system for the 2000 model year, but I've had this truck in both Texas and Florida, and never encountered this before.
I replaced the water pump and radiator (Mopar parts) two years ago, and did a reverse flush on the heater core to PUSH out any debris that had settled on the inlet side. I don't believe I'm dealing with a clogged radiator, and I certainly don't believe the water pump has failed. Thermostat was also replaced with an OEM Mopar part. Viscous fan clutch seems okay as can only spin the fan by hand just a short distance before it stops; fan spins when the truck is running, and quite fast too.
Think that covers just about everything, maybe it's always been like this, but I guess I'm hyper sensitive now about the temp gauge after having a failed cap allow the coolant to boil off.
Truck is at 89830 miles.
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