My 2003 LR Discovery 2 is running hot at idle (221 F). I shut it off at 221F not wanting to damage anything. What should I do first: add coolant, install new coolant and install a 180 degree thermostat? Does the 180 degree thermostat bring down the engine temperature? My secondary fan is switching on at 210 F.

 

A faulty thermostat is one likely fault and a good place to start. There are a number of other possibilities as well. If you get an in-line thermostat it’s easy to remove the t-stat completely to start troubleshooting. But if you replace the stock t-stat then yes use a 180.

 

Thanks for your help!

 

Maybe start by reading the stickies at the top of the forum.

 

I read your post on thermostats. Very informative. Thank you

 

You mentioned needing to add water. Start with a proper bleeding of the system so the coolant level is fully topped off (in the stickies) before you start throwing parts at her.

Faulty thermostats are common. So are faulty radiators. I am a huge fan of the inline thermostat mod.

An internal radiator clog is hard to spot without a ir thermometer. An externally clogged radiator will have ample mud clogging all her fins..

 

Hot at idle, bad thermostat or clutch fan. Cool at idle but hot on the highway bad radiator. Hot everywhere likely bad thermostat.

 

The fan is usually the easiest thing to diagnose. Turn the blade cold and it should have the resistance of a spoon going through peanut in butter.

Once warm the blade should spin almost freely.

I suppose damaged or missing fan shrouds (there's and upper and lower) would also have a huge affect at idle.

 

No, a 180F thermostat switches coolant flow from the bypass path to towards radiator at 180F while heating after start. Compared to a 200F thermostat, the 200F will switch coolant paths later when engine gets hotter after starting. A thermostat function is to avoid the engine running cold, not to run cooler.

 

What temperature thermostat would be recommended?