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Downhill Overheater

My 2000 Dodge Dakota “sport” 4x4, 4.8L V8, overheats when going down hill and when idle. As soon as it’s under laod or reving at 2500rpm in neutral. So when going downhill I shift into N and rev it up, I also do the same when stuck in traffic or at a stoplight. Whats Gives?

Oops, when reving it cools down…

My first step with pretty much any overheating problem is to change the thermostat and radiator cap because they’re cheap, they’re usually very old and they can cause a large variety of hard to track down cooling system problems.

What’s probably happening is you’ve got some sort of constriction in the cooling system (such as a partially-stuck thermostat) that’s preventing the coolant from circulating at low engine speeds when the water pump isn’t turning very fast, but when the engine speeds up it increases the coolant system pressure and it can overcome the constriction and force the coolant to circulate. If you’re lucky, it’s just the thermostat, but otherwise you might have a plugged radiator or hose or possibly a weak water pump.

It kind of sounds like water pump to me but Greasy gave you some good general advice.

I have to agree that the water pump impeller blades may be erroded away.

When this happens, the water pump can’t move the coolant out of the engine fast enough to prevent the coolant from overheating at low engine speeds.


the clutch fan is smoked.

viscous coupler,is no longer coupling.

see ya!

smokey gone!

xychrom must live in very hilly country for a car to get hot going down a hill. Standing at a stop is another thing!

Maybe a little more information would help. Have you kept up with oil change intervals? Using the recommended oil? Have you been using any oil additives? Any recent indications of low oil or low oil pressure? How many miles on the odometer? Is the coolant level correct?

Besides checking thermostat, also do a vaccuum pressure test. It can tell you all sorts of things. Even backed up exhaust can cause the engine to get hot. Also check with your voltmeter the Coolant Temperature Sensor. Are you pulling any diagnostic codes?

Downhill Overheater
This Dodge Sounds Like Another Candidate For “Overheaters Anonymous,” Sorry!