Running hot

DPW19673

MEMBER
2000 DODGE TRUCK

V8 Two Wheel Drive Automatic 161000 miles

I have had this van a long time. It always ran about 195 to 205 in temp. I recently noticed when driving down the highway only when I am maintaining a speed about 70 mph it starts to very slowly get to about 215 - 220 degrees. It had no leaks we replaced the thermostat with new coolant checked the system for air and the radiator was flowing nice. Took it down the highway for about 25 miles or so and did the same thing. Then we changed the fan clutch went 25 miles at 70 once again it heated up to about 215 again. I let it cool down and did the 25 mile trip for the 3rd time only this time I turned on the heat and it stayed about 195. Now when I do city driving it is fine it only does it when I am maintaining about 70 for 25 miles or so. Please help I am stumped. Sorry for the low donation as I need to get from Florida to buffalo to start a new job and I am kind of broke.

1 Reply

IMPALASS

MECHANIC
3,112 POSTS

Hello, just a couple of things. You never stated if you changed the water pump. The impeller on the pump could be deteriorated. It is possible that it isn't able to push the coolant through at high speeds. My other thought is replace the radiator cap. It is possible the radiator needs flushing, but I would think it would have problems in town. However, that is a possibility that at high speeds it isn't able to move through there very fast and stay cool. I would do the cap, and then go for the water pump then the radiator. Also, have you checked the codes? Stop by Auto Zone or O'Reilly's and for free they can pull the codes. In order of what I suggest, go to AZ and pull the codes, while there get the cap. If codes, you need to see what they are. Either which way, put the cap on and drive it and see what happens. Then if the codes are clear, new cap and it still does this, my suggestion is the water pump.