I dont know if this applies but for the last two weeks everytime i would driver the truck it would be fine. i live in florida so its fricken hot... If i parked and would drive again later that day when i got stuck in traffic it would spike a bit but never to the red. It would though just border untill i got to highway speed. I just did a new water pump and flushed the system. Well yesterday when i went to take a quick drive i noticed in the driveway a wet area near the front tire just behind it. I was in a rush so i just didnt pay it a mind. 2 miles and it was starting to get hot and i could smell antifreeze. I parked and popped the hood and it was leaking from my overflow tank. You had to look hard but underneath the line going to the intake was leaking. I touched it and it just broke off. It was pretty brittel from the heat over the years. well i went to my rover parts guy and got a used one from a newer year and put it in. Topped off the tank and was good to go. I think that when it started to go bad it was causing the heat spiking. I dont know if this could be the cause but maybe worth a look.

chris

 

Okay, so I replaced the t/stat and boiled the old one. The bloody thing opened, but it didn't seem to open until the pot had reached a rolling boil - too late in my opinion (water boils @ 212, the t/stat is supposed to open at 198...). The system has brand new coolant.

 

All we can do now is wait and see.
Keep us posted.

 

If it still overheats I'm going to assume the next culprit is blockages in the rad itself?

 

Okay, drive on the surface streets to dinner. Perfectly fine. Got on the freeway to test it out.
After a few miles going 70 she started to overheat. Got off the freeway, and it started to cool off almost immediately. Stayed at about the half way mark all the way home on the surface streets.

No visible loss of coolant. No coolant in the oil.
Help??

 

Check your belt routing first, if ti is on wrong the water pump will turn to slow.
http://www.roverparts.com/TechTips/s...g_defender.cfm
The next cheap thing to do would be to check the radiator for a blockage.
Next after that would be a bad water pump, if the impeller is going bad it wont pump coolant fast enough.

 

Okay she's at a radiator shop getting cleaned out and acid bath'd.

What are the odds of cracked cylinder or hg?

 

Slim to none.

 

Okay good. I've been feeling somewhat ill all day with the thought that my new baby might be broken...

 

Well as long as it didnt reach the red you should be ok, but if you ran it while in the red then you may have toasted it, but you made no indication that you ran her into the red.
Shes going to be fine, maybe a new radiator but thats not the end of the world.