1999 Durango started overheating
I own a 1999 Durango 5.9L, 4x4, with towing and off road package and 221,000 miles (I am the original owner). I recently returned from a 3,600 mile road trip. Before leaving, I had an oil/filter change and a new air filter. I also had the thermostat replaced due to a slight leak around the gasket. Keep in mind, this was the original thermostat.

My vehicle has never had an overheating problem except when the water pump went out and was replaced in 2011. About 1000 miles into the trip the vehicle started overheating, the Check Engine light came on and it started idling rough. I was in Oregon at sea level and made it to Portland where I took it to a reputable mechanic recommended by a relative. He ran a diagnostic and found the #4 cylinder was not firing. He also noticed a coolant leak around the timing chain cover and thought that could be causing the overheating. The $725.00 repair entailed a complete tuneup, replacing the timing cover gasket and replacing the thermostat with only about 1,000 miles on it.

The vehicle was running at normal operating temps until about 1,500 miles later. The temp gauge then started going from normal to about 3/4 hot. Checked coolant and had to add about 1/3 gallon. Problem continued to get worse till the gauge went into the red. Adding coolant didn't help and the heater was blowing cold air. The vehicle ran fine.

I don't see any leaks but I went through 3 gals af coolant during that trip. Any ideas?
(Sorry. I first posted this under new member)
Last edited by transjam2001; Today at 11:25 AM..

 

I also just checked upper/lower radiator hoses. Top was hot. Bottom was cold. Sounds like a circulation problem since heater also blows cold air?

 

Maybe a clogged radiator or bad pump. Did you also replace the bypass hose when you did the pump? I forgot to change mine the last time and it would up leaking down around the timing chain cover making it look like it was coming from there.

 

I broke down and took it to my mechanic. He's baffled too. I'll post the outcome.

 

thermostats are like everything else/ not made like they used to be...

 

My mechanic thinks the problem is due to a bad head gasket and/or an old radiator.

 

Bad head gasket, bad water pump, or a bad T-stat.

I'm leaning to head gasket because the light came on and engine ran rough. Most likely the issue was caused by the shop you took it to the first time.