Problem with my truck

[mydesigner]

I know this isn't a buick but I need some advice I hope this is the correct forum. Today I was driving down the highway in my 85 GMC pu. I looked down and my truck was starting to get pretty hot so i started to pull over and POP blew the upper radiator hose to pieces. So put a new one on and it still got really hot really quick. Put a new radiator cap on and seemed okay so went to school and started heading home. I live about 12 miles from my college and mostly highway. When i was pulling in my driveway the temp was starting to get back up close to 260! It usually runs right a 210-220. After i changed hoses i put straight water in it, would that make a difference in it getting hot. On the highway the temp was alright, But when i got off it got hot. Should i go ahead and add antifreeze or does it actually make a difference? Thanks for any help

 

[2QUIK6]

Straight water is not good for it in the long term, but shouldn't make that big of a difference in temp. Tap water in general is not good in a radiator because of the lime/scale build up that will occur from tap water. Distilled water is recommended.
Now for what else could be causing it to run hot...have you checked the radiator by looking down the end tank with the cap off to make sure coolant is passing thru the holes/coils freely and flowing good...maybe the tubes are clogged with scale.
Is the thermostat opening properly, change it as its easy to get to on that year truck.
YTou can usually tell if its opening by making sure the coolant is flowing good per the procedure mentioned above. If its not flowing and the tubes are not clogged, then its either the thermostat or the water pump, but usually the water pump will leak when it goes bad.