My wife has an '02 Durango with 103K on it and the 4.7 engine. 2 weeks ago she was on her way somewhere and called me to say the alarm bell went off and the temp gauge was rising. It never pegged though. It took almost a gallon of coolant to top it off. I checked the dipstick to see if it was in the engine and thank goodness it wasn't. Looked under the car and no signs of a leak so I figured oh well we'll see what happens. She drove it back and forth to work for the last 2 weeks which is a 16 mile trip each way without incident.

Today we set out on a 300 mile round trip of mostly 70 mph turnpike driving. 75 miles into the trip or half way to our destination the gauge starts to rise. I figure it was just an air bubble that needed to work it's way out. Yeah right. I make it to the rest stop and add about 3/4 gallon of water to get it topped off. I then drive about another 35 miles and the gauge is on the rise again. I now notice that the coolant overflow is full to the top so I figure coolant is getting pushed back past the cap but why? Things are fairly hot under the hood and I grab the fan and it spins freely. So I figure I need a new fan clutch. I get one and install it with the $90.00 worth tools that have to buy because of course I have nothing with me. It's always nice to have doubles of everything especially a fan clutch wrench. Back to the story. Go about another 35 miles and now that the overflow tank is full I start to see drops of anti freeze on the windshield because it is pushing fluid out again. This time I stopped and bought a new radiator cap. Finally made it to the amusement park 3 hours before closing.

On the way home more of the same BS. Topped off before I left. Drive about 35 miles and start to see the drops on the windshield. Go a little farther, stop and add about a half gallon. Repeated this 3 times on trip home.

Anybody been through this and have any ideas? Do these things have head gasket problems like the old late 80's small block chevies that caused them to overheat? Any help will be greatly appreciated.

Thanks. Scott.

No new thermostat yet? Just for grins, I know it doesn't make sense, but is easy task. (located at engine end of lower hose). If you suspect cylinder combustion pressure is getting into cooling system, you could fill cylinders with compressed air, one at a time with rad cap off and see if rad level rises. I am not a dealer tech, but those head gaskets are mls and usually hold up well. (unlike the 89-90 chevs)

Do you by chance have a rear heater? If so, it takes forever to get bubbles out of the system. It took mine about two months. I followed the FSM recommendations but it did not help. Finally, just moderated the driving until it finally coughed up all the bubbles over about 2 months. Keep an eye on the overflow and make sure it never gets too low again.
Craig

My durango did that and even though the coolant looked great the rad was clogged. when its hot not to hot touch the radiator and see if there are hot and cold spots on the finned part. Or if you know someone that has a infer red laser temp reader use that. I had a big area that wasnt even hot and others that were very hot .

check your rear heater lines I replced a dozen on rear heatin the old b vans

If it only overheats at highway speeds and is ok on shorter trips in town put a radiator in it. If you look at it you will see the lower radiator hose attaches half way up the tank on radiator leaving lots of room in bottom half to plug. Another indication of this is if it blows coolant past radiator cap and out overflow

How can it be so hard to get the air out of these things? And this can cause all of this overheating? This stinks. The car has developed a noticeable miss over the last few days though. The miss does make me wonder about head gaskets. If you do a Google search tons of horror stories about the head gaskets come up. Oh boy, what to do??????

Pull some spark plugs and take a look at them. Look for discolorations that dont match the others.

I found out that the problem was a head gasket leaking coolant into # 1 cylinder. I can tell you that the shop that is repairing mine has seen this on 4.7's many times. Hoping to have it back this week. Just letting everyone know and thanks for all of the help and suggestions.

Seen a few with head gasket issues. Not all that common. That 4.7 has been darn good engine. Seen quite a few more 5.7 heads off then the 4.7.p