Hi everyone,

A while back I purchased an Ultragauge for my 03 Discovery and had issues with it running 212-221 when driving. A coolant flush revealed that the Dexcool had turned into sludge. I flushed and replaced the thermostat in my truck and all is good. Even in 90 degree temps. I am curious as to what a safe operating temperature is. I am aware that the 03s in particular are prone to slipping liners when overheated. What temperature would you guys consider "overheating" without looking at the stock gauge? I typically am seeing 188-195 during the winter but have seen it go up to 208 in the summer. Is this a cause for concern or is this normal?

 

206-208 is pretty normal for the standard OEM thermostat from what I have seen. Some will jump in and say if you bleed it just right you will see 190s with OEM thermostat but I never got there. You can go inline thermostat to reduce the temps more.
Overheating is near 250

 

I should have specified that I do have a 180 tstat installed. I am very nervous about the engine temps lol. I ran the truck with the temps in the 212-220 range without knowing for over a year so I guess no harm was done, but I do not want to deal with a head gasket issue. Especially because mine is on its original set with 128k miles, somehow. It doesnt lose any coolant at all either, it is a miracle. 😂

 

220 was the original operating temp but overheat is 240ish and it will get there fast if there is an issue. In 105 deg temp 15-20mph up a 12-14% grade for 20 minutes mine hit 215-217 at the hottest with the inline 180 - 164 on down hill on the other side. Stock gauge never budged.

Normal for me 183

 

Optimal is 170-180 which is where the inline thermostat will have you operating, the factory 180 thermostat will have difficulty keeping you under 190 on a hot day.

 

Does the Disco like it better at 170-180? I seem to remember hearing that those temps may cause emissions issues? I've been shooting for 180-190 with my mods, but if it'd be happier even cooler, maybe I'll go ahead and get another thermostat. I assume the ones in the Extinct kit are BB Chevy stats?

 

Do the inline. I’m still kicking myself for not doing it sooner and believing stock is better. Here is one of my tests after installing.

 

Two facts with the Disco 2 operating temps. Number 1 - anything under 210 is absolutely fine. Number 2 - Extinct's inline thermostat is the best upgrade you can do for your truck. I always thought I was fine with a 180 factory style thermostat. I was wrong. The inline setup is far superior. #facts.

 

I run 170's in my 00's and get 17 mpg consistently. The 03-04's will throw a code if you run lower than 180, but they have 4.6's so not fair to compare mpg apples to apples. I have seen no negative to running down at the 170 level. The Chevy stats will work, really any of the standard 2 1/8 stats will work which were used in a lot of vehicles. SBC might resonate with your local parts suppliers although it needs to be the 70's models so they are not a bypass thermostat model.

 

That's what I thought I remembered, that the 03-04 would set a code at 170, why I bought the 180 stat from you when I ordered your kit. I'm setting up my e-fan upgrade to keep the system between 180-190 at all times, but would've been happy to go colder if the system would've liked it.