doh!!

 

I'll pull it and double check. Need to get another new t/stat gasket along with my new radiator cap... grr.

 

That is the worst part of replacing the t-stat, geting a gasket.
Just a though, you might want to replace that t-stat with another brand new one as that one was overheated several times and now may be no good.
Might be worth the $10 for a new one.

 

Good thinking. I thought I'd boil it before putting back in, but maybe a whole new one is in order...

Thankfully British Pacific warehouse is about 20 minutes away so getting parts isn't hard

 

You can also buy the t-stat at AutoZone or NAPA.
I would hate for you to waste yet another gasket putting in your old t-stat and then finding out it was just bad.

 

Changed the t/stat, which was in backwards. Ran the engine up to operating temp (until the t/stat opened) and then shut down, and topped off the expansion tank.

Drove a few miles on the motorway without a problem. Pulled into a parking lot and it promptly began to run hot. Frustrated, I played a round of frisbee golf and came back to the truck, checked the expansion tank and it was maybe an inch below "full". Topped it off and drove home without a problem, then to dinner and back. Let's pray it was just a bubble from a low coolant level... I love my rover but this is seriously driving me off the wall...

 

Thats what they do, they get you hooked and then drive you insane trying to figure them out.

 

Yea, they call it methamprovermine........

 

Okay... I hope I never meet a rover engineer while i've got a gun in my hand.

Radiator is perfect, t/stat is perfect, coolant is brand new and properly bled, new radiator cap, slight (talking a drop or two per trip) coolant leak on the upper rad hose.

She threw a code, vacuum leak on the IAC motor. Emissions thing, although it's possibly leaning out the engine a bit. Otherwise the fan clutch is nearing the end of it's life (doesn't explain the high speed overheats!). Those are the only things I can come op with that are known to be wrong. I am told by more than a few reputable people (plus all my personal diagnosis) that I do not have a cracked block or blown hg.

Last night during a 20 mile highway trip (~65-70mph) she started to run hot twice. The first time the needle almost hit the top of the safe mark, hoping it was an air bubble or something I floored it, the tranny kicked down and so did the temp gauge.
Then, maybe 10 more miles down the road, she started to run hot again. This time I floored it and the temp went up, so I let off the gas and it went down!

And that is the frustrating part. The car has no idea what it want's to do, and sometimes one fix works and other times it makes it worse. There's no rhyme or reason to it, and therefore no way to accurately diagnose the problem!!!! Arrgh!

 

Lets start with the basics, have you checked your belt for proper routing and tension?
How old is the water pump?
I have been told but cannot confirm or deny this, but running to lean will cause it to run hot.
http://www.roverparts.com/TechTips/s...g_defender.cfm