Weird overheating problem?

I have a 2002 with the 4.7L that I am having overheating issues that I have never experienced before. When driving around town or even on the highway under 65 my thermostat never goes above just under halfway. Driving in town I have yet to see it go above that point. However, when driving down the highway if I increase my cruising speed to 70, my thermostat climbs. When going 70-75 it will go up to about the 1 o'clock point before I turn the heat on slow down, so I don't know how far it would go if I continued. I replaced the thermostat since it's easy and cheap to replace. But the problem remains. So what is it about driving more that 65 that makes the temperature rise. Any vehicle I have had in the past, if there were overheating issues, they happened in town in stop and go driving, I have never even heard of a vehicle that only gets hot when driving on the highway. Any ideas? Thanks in advance.

Victor

not saying this is your issue,but i have heard of head gasket issues on the earlier 4.7 engines. sounds like a weak water pump though.

i agree, probably the water pump

Pump

Ok, so I am going to replace the water pump and hope that helps my overheating issue. My questions is this. How difficult is it do? I am somewhat mechanical, doing brakes, oil changes, changing an alternator here and there, and I have done a water pump before, just not on a Ram. I have the money to either pay to have someone else do it or invest in a low end compressor like this
Shop Campbell Hausfeld 1.3 HP 20-Gallon 200 PSI Electric Air Compressor at Lowes.com

I usually would rather invest n tools and do repairs myself but don't like getting in to something I can't finish. Thanks for the advice.

Victor

It's not a terribly hard job once you can get the fan off of the water pump. If you have never had the waterpump changed on your truck, or even if it has been a couple of years, that fan will seem to be organically grown onto the pump!

I changed mine out the last time with hand tools. Basically what worked for me was to clamp a large vice grip onto the top of the water pump pulley and let it push against a metal piece there while I loosened the fan. After that it was a piece of cake to replace the pump and the hardest part left over was getting the air out of the cooling system (which isn't really hard at all).

OK, so I got it changed with out an issue and went ahead and changed the fan clutch while I was there just to make sure it wasn't causing any issues. But I am still having an issue of it overheating when I drive on the highway over 65 mph. So in the last week I have changed the water pump, fan clutch, thermostat and about a year ago I replaced the heater core. What else is there? What else could cause this overheating issue? Thanks in advance.

Victor

did you ever end up finding out the reason for this, i am having the same issue on my 04 4.7 ram and today i decided to check the oil and the dip stick was dry. i am of course leaning towards head gaskets but its not getting fully to the point of over heating.