Stock thermostat I ran 206 max in traffic or stop and go 188 to 194 hwy. Got a new 180 from AB now my temps easily go to 203 204 stopped or cruising at 45 mph?

When sitting in traffic if I blip the throttle it will drop acouple degrees instantly. The upper temp isn't bad but surprised at the cruising temp..

Ab went me a white one that is supposed to be the soft spring 180 degree

 

Just make sure bleed the system of air. When cooled down, top it off through the bleeder valve on the Tee. Reservoir often is full but the top hose has no coolant yet.

 

Yeah I've added a couple ounces of coolant that way the last 2 mornings. I was really expecting closer to a steady 188 to 190 going down the road. To be honest I haven't taken it up to full highway speed yet for fear of the temps climbing but the heat is hot and no waterfall sounds

 

Lots of reports of mislabeled or bad 180 stats from AB. You should get either the black Britparts one or the Grey OEM one from Lucky 8.

 

If you're running 200 degrees, opening the thermostat at 180 isn't going to cool it off more some how. It just results in a lower minimum operating temperature. With given ambient conditions, to cool it down from 200+, you would need more water flow, more air flow, or more heat exchanger surface area. To flow more water, make sure the water pump is working to spec and not weak. You could also decrease the pulley size. For more air flow, make sure the fan and fan clutch are working properly. If your idle temps are high, the fan may be underdriven due to clutch slippage. For more heat-exchanger area, make sure the radiator is not clogged. It can clog with solder bloom, rust, mineral deposits and other junk.

With a new bronze-impeller water pump, new fan-clutch, and a radiator that is serviced off the vehicle according to its needs, the Rover V8 should run cool. It won't necessarily keep the coolant out of the cylinders, but it will at least run cool so long as it is full of coolant.

 

My temps were lower before changing the thermostat

 

In my experience this is not true. I was running 216-220 down the highway and people said the same thing. "Switching to a lower thermostat won't help". I switched to a lower temp thermostat and temps went down to 188 on the highway.

 

I hate to kick the dead horse...I got my 180 from Lucky8 and my max temp during summer with AC on was 194 at idle. Underload it drops to 184. It could be the wrong T stat and the only way to check is boiling some water with a temp gauge and seeing if the T stat opens.

 

I figured I was safe buying from a reputable source.. ab is sending me a new one free of charge but the swap will cost me 30 bucks in coolant and a few hours I really don't have to spare. Sadly they admitted there have been quality issues with them. They really should stop selling that part...

 

All thermostats are stamped inside with the temp in C, the overall engine temp is going to vary on terrain, location, air in the system, fan/fan clutch, HVAC on/off, outside air temps, humidity, and how your D2 is loaded down, or equipped. The #1 thing you want to see with a D2 cooling system is when the temps climb that it goes down if you slow down or say the AC cycles off. I did a lot of idling at HCRR, and I never saw temps over 209F, once I got on the move I stayed in a lower gear on purpose as the clutch fan seems to lock around 2000RPM - 2500RPM, and once on the move I saw 209F quickly turn into 200F, then all the way down to 190F. D2's rolled out running fever's from the factory thanks to more strict emission laws in the USA, back then brand new our trucks were in the 220F range easy. 209F on a hot TX day out on the trail = nothing a well maintained D2 can't handle.