Well, heading home Sunday night my temp light kicked on very fast. Ultragauge read 250°! Shut it down immediately and got it towed. Coolant puked from the reservoir and the top hoses were hard. No heat from the vents. The oem 180 thermostat was only one year old. Head gaskets were done 30,000 miles ago. Do you think I'm OK? Again, I shut it down immediately and had it towed home. New thermostat should arrive tomorrow. I'm a bit nervous. I hope there is no damage.

 

Hopefully you might have shut it down in the nick of time and no overheating damage if you are lucky. Take the advice of the guys on this website and maybe, if they recommend, fit an LR OEM TD5 thermostat which opens at a slightly lower temperature.

 

The lower temp oem is the one that failed. It did lower temps for me and was running great until it decided to fail and stay closed while driving. I was typically running 188-195 while driving, 204-206 at most while idling in summer.

 

Did you take it out and inspect it? I bet something got in there and caused it to fail. I've had that happen after putting radiator cleaning products in my car. It broke off a sizeable piece of crud that blocked the thermostat.

 

You should set your Ultraguage water temp warning "buzzer" alarm. I set mine to somewhere around 215. This can prevent how far your temp escalated.

 

I have a brand new genuine 180 I'd let you get for a reasonable price

 

Update....installed new thermostat and bled the system. Idled at 195 for 30 minutes and heat was hot. Took it around my neighborhood and it hit 220 again. Top hoses were hard and it puked coolant again. I'm going to put on a new coolant cap to rule that out, but I think I'm looking at head gaskets again. After it cooled down, I started it with the coolant cap off and it began to overflow within a minute. Seems to be a tell tale sign of a failed head gasket. This came on with no warning. It ran great with no leaks and didn't run hot. No milky oil. I think they just failed without warning. This sucks.

 

Hmm I would spend a few bucks on a coolant tester for combustion gases

 

I have my Ultragauge temp alarm set for 215 also.

 

So how do you definitely know it's the stat that has failed shut?

IMO you have other problems which are causing overheating, like HG's etc.