I have an 01 Durango, 4.7 SLT. 195,000 miles.

On a recent trip I was stuck in a trafic jam in 95*F temps. So I was naturally keeping a close eye on the engine temp gauge. It went higher than normal, and kept climbing. Never went to the "Hot" side, but got close. Eventually traffic started moving and things cooled down. Never got down to where it would normally run, but not on the hot side either. I was able to make the 250 mile drive home in 90* + heat. So I have been keeping an eye on things since then about three weeks ago.

It still seems to run a little hotter than normal. If I remove the radiator cap when engine is cold, then start engine I can see the fluid level increase. If left running with the cap off it would eventually overflow out the cap hole. As if there is pressure being put into the coolant system. Engine runs fine, no missfire. No smoke, or steam from exhaust. No sign of water in the oil, oil in the coolant. No trouble codes.

I'm afraid that it has blown a head gasket, or started to. Or possibly an intake gasket. Of course I hope that it is something simple.

Any input? How to diagnose further? Would a computer scanner help determine a head or intake gasket issue?

For what it is worth, the fans work although the clutch driven fan seems to slow down speed like it may be weak.

 

It could be possible that the clutch for the fan is going bad. It should slow down once the engine is at normal temp and speed up when it's hot. When the engine is cooled off (and turned off obviously) spin the fan by hand and see how far it goes. If it goes more than a 1/4 turn or so it's bad. You did say that the electric fan is working, no?

I don't have any experience with the 4.7 myself, but I do understand that you have to manually burp the cooling system, maybe you have air in it.

 

With 195K and if you have never replaced the fan clutch that is what I'd do first.
Running the engine with the radiator cap off it will always overflow.
The are test strip or other ways to see if you have combustion gases in the coolant.
You can do a search for testing the fan clutch.

 

By the way, get a mopar fan clutch from the dealer. I know it's more, but all the aftermarket ones are pieces of **** and engage way too often, dragging down the engine, which means less power and economy.

 

Thanks guys. That was fast response time.

I was hoping that the fan clutch might have something to do with the issue. It is certainly worth a try.

"Running the engine with the radiator cap off it will always overflow."

That is very comforting information.

I have never changed the thermostat either. A clutch fan and thermostat will be my first efforts.

Unless of course someone else chimes in with more information.