My dodge Dakota 4.7 recently started running hot but only when driving at slower speeds.
What could this be.
Radiator stays full

 

I think you fan is done. with the truck running take a rolled up news paper and put it in to the fan if the news paper stops it the fan is done if it dos a numer to the paper the fan is fine. My 01 4.7 was doing the same thing and it was the fan

 

As shadowm442004 says

Check the mechanical fan

I would also check the Efan

 

With my past experience I would say water pump!! With time the fins on any water pump get eaten away smaller and smaller thats why you have to drive at higher rpm to circulate the coolant properly

 

Im just going too replace the water pump I bought a hytech water pump which is all aluminum even the propeller. What do you think about motorad failsafe thermostat?
I got zerex g10 antifreeze too from zero.com it was $25 for 2 gallons is this enough antifreeze.
How can I get all the antifreeze out? This is important I get all of factory antifreeze out as it won't mix with zerex right??

 

Its zerex G-05

 

Dodge starting using HOAT antifreeze around '01. You likely already have it in your truck so it's not really a big concern. Check the owners manual.

The easiest way is to use a flush kit on it. It splices into the heater hose and flushes out the coolant passages. The system will always have some old antifreeze in it if you just drain it. 2 gallons should be plenty.

 

I dont think it matters what type of coolant is used bottom line is you cant mix the different manufacturer types (ford, gm, honda, etc.) To make it simple! Thermostat same thing if you're going to use extended life coolant dont get a cheap t-stat I test mine before I install them for proper operation on the stove with a cooking thermometer, on the copper tab should have a temperature rating, at that temp is when it should be "fully" opened... I would recommend flushing the system anyways due to the particles left from the last pump! Just remove the old t-stat and bolt housing back on, remove top driver side radiator hose at radiator and remove fill cap, place running garden hose in reservoir and start motor your going to make a big mess just make sure to cover and not get the fuse box wet at all!!! When only tap water is comings out turn off water a let engine finish flushing for a couple seconds if you wanna get the tap water out and you should! Flush two more gallons of distilled water thru the system very important dont leave tap water in the system!!! Remove the bottom hose to empty the remaining water and the rest should be easy hope this makes sense im not the best at giving direction lol

 

Your pump blade fins should never get eaten up if your coolant is in good shape.

 

Can someone please tell me if the rad has a drain plug if so where is it