I have read and searched. I have a 03 Durango with 114K. Replaced Rad cap with 20psi. New upperhose with ned rad filler. New clutch fan.
new t-stat. Coolant flows with no obvious restrictions.

I have been dealing with this for about a year now. It will go 2 weeks with no issues. Long trips, I lose rad fluid. Pulling my trailer, same thing. Lost of rad fluid equals overheating. So today, I just got back from a 300 mile trip, I notice, the more rad fluid I add by taking off the cap, the more the reservoir filled up causing it to leak out the over flow causing coolant to leak. So, The rad seems to be kicking the coolant out to the reservoir. I can drive 200 miles straight on the highway with no issues.. As soon as I slow down and stop. It seems to kick the coolant into the reservoir causing it to come out the overflow and have overheating prob. If I drive around town it does the same thing. I could drive around town all day. But as soon as I hit the highway for 50 miles and then get back to around town driving. It will do it again.

I have burped it.. (Ran it at 2000rpm for about 30 mins) Flushed it. Even took it to a shop and they pressure tested it and everything looked OK and they could not replicate the problem.

Not sure what is causing this. I have a new Radiator and will probably install it next weekend. But before I do that. What to see if there is anything I'm missing.

Also did a tranny service on it.. Dropped the pan and change the oil and both filters.

Thanks for any help.

Its a 2003 Durango 4.7l 114k miles

 

Are you certain your water pump is working properly? It sounds like you have decent circulation at steady highway rpms but having problems circulating with stop and go fluctuations. Just a thought...

 

Another thought, you had it burped. Did you loosen the orange-colored allen key near the top of the rad hose on top? Did you park on a slight incline to make sure the bleeder valve was the highest point of the system? Did you see coolant leak out of the bleeder when adding coolant before tightening it back down? Could be air bubble still in the system?...

 

This should be a stupid question but what was the mixture percentages you put in the tank? If there's too much water it will boil off and cause it to run hot in the city.

Make sure its right at 50/50 (water/coolant ) ratio.

 

What about the electric fan, is it running?

 

I run premix 50/50. All fans run. I Burped it both ways. The hex nut and also removing the rad cap and burped it.

This is what happened today. By the way, I am replacing the water pump. The old one was plastic blades the new one looks like it is casted. Looks a lot better then the original.

So Today I was running it and burping it again. I fill it up where the rad cap goes. This is what I get.. I fill it just to where the tube that goes to the reserve. When i do that I get tons of bubbles. Non stop. But when it goes below to where you can actually see the water flow, I get no bubbles.. Just when it is filled to the top. I'm thinking maybe it is sucking and blowing bubbles because it is filled to high.. But anyways..After about 30mins I put the cap back on and ran it some more.. Idle and 1500rpm. So I go and close the hood and I see it leaking again under the car. It made a new puddle.. (The first puddle was from me) So I look under and I see it dripping almost a steady stream. I couldn't really see up under it because of the belt and the pullys.. But i'm guessing it was the water pump gasket?? Its not leaking from the weep hole as that is on top. But then it stopped once I opened the hood back up and took the rad cap off again.. And I couldn't get it to do it again.

Any thoughts on this??

A new water pump will be put on tomorrow.. The old one looks really good.. The shaft seems tight and no missing blades.. But it could be something else.. Also will be replacing the radiator.

 

Also.. After draining the coolant.. I know for certain there is no oil in the coolant and no signs of coolant on the dip stick.. This was one of my concerns was the head gasket as it has overheated more times then I can count.. It has overheated at least 3 times to where the truck had shut off.. But this was due to not being able to turn it off in a safe place (Freeway, traffic) I did have the coolant tested and no CO2 in system.

 

Another stupid question: Did your guy replace the lower hose when he did the upper hose? Were the hoses OEM? Because only OEM (IMHO) are best for hose replacement. Did he reuse the spring clamps or did he use the SS screw-type? The spring clamps lose tightness after a while and they are really meant to be used once.

 

Lower hose will be replaced. They are not OEM.. On upper hose. Spring clamps came with the replacement hoses. I don't like screw type unless it is the industry type with an actual nut on it.. I do use those as they seem to hold better.

And BTW.. I Am the "Guy"

 

Could be the pump going out and leaking at the weep hole at the pulley. Replace the pump, bypass, and lower hose. I would only use a new pump and not a rebuild. Help to seal it up with some Ultra Copper RTV.