My 2002 disco just had much of its cooling system overhauled.

Coolant flush
New radiator
thermostat & housing
water pump

on the freeway the lowest it got to was 212. It jumped to 217 if I accelerated past 75 or was climbing. Sat in the mid 220s for longer than I liked - hills + traffic.

What concerns me is that I didn’t see the temps drop below 212 on the flat freeway in 77 degree weather.

All these temps were collected with an UltraGauge blue.

My indie shop considers 225 normal. Regardless I’d like to lower temps - I know I can use a 180 thermostat but I’m thinking there’s another problem I should fix first - it shouldn’t run this warm after everything was changed right?

 

If you're running the stock t-stat, I think it opens at 195. I'd expect to see something below 212 on the highway, especially with the new parts you mentioned - a peak of 225 may be normal from the factory, but it's not going to do your engine any favors from a longevity perspective, and I'd be surprised if trucks were running at that temperature from the factory.

I'd just contact @Extinct and get one of his inline thermostat mods. That should keep your temps in the 180s, and it's a better system than just swapping for a 180 stat. It's possible you're running a little hot due to air in the system, so you could check to see if the coolant level is full, and you can remove the bleed screw (while the engine is cold!) to see if there's any air in there. But at the end of the day, the inline stat is self-bleeding so it will prevent a lot of headaches. You can install it yourself with basic tools.

 

I emailed extinct so I definitely see myself swapping it out. I just want make sure I cover my bases first rather than just hide a symptom.

Any way of confirming the coolant cap/reservoir aren’t causing this? I’ll check for any air in the system.

 

@Chris59 if it is the cap you should have no pressure after a couple of hours, but what thermostat is actually in there right now. There are a bunch of whitish ones that seem to have been pretty random on temp.

 

Those temps are within the OEM thermostat temp range. Either 180 Grey Stat or 180 inline mod. Also you've got to make absolutely sure to get all the air purged out of the system.

 

@Richard Gallant According to the work order - PEM100990K. I believe this is the original temp oem Tstat.

@Best4x4 what I was hoping to hear - guess it’s time for @Extinct ‘s tstat.
I can’t imagine driving this d2 too much longer at these temps.

 

I ran 2 03's when they were new up to 159k/189k and I never had any HG issues. These engines can take up to 220F heck probably 225F, but they aren't spring chickens anymore so keeping the temps in the 184-215F range, replacing the plastic T & Y with aluminum parts, and switching to green coolant will certainly prolong the life of your D2. I'm also a firm believer in deleting the awfully designed Throttle Body Heater Plate as I've seen way to many engines die a slow death as the coolant trickles out un-noticed until it overheats and then it's sometimes to late.

 

@Richard Gallant Of course I find your thread after posting - https://landroverforums.com/forum/di...ntified-99940/.
Lots of helpful info here - Thanks. i'll be running through most of your checks just for my own sanity.

@Best4x4 Head gaskets were just done so this seems like a good point to start keeping the temps low. Do you remove the throttle body heater plate on all your discos?

 

On every single D2 I certainly do. It's a poorly designed unit, and all of them eventually will leak, or leak again. I don't live in the Artic Circle (more like the Sahara lol) I want my cooling system to be as trouble free as possible.

 

After a few more drives/days of monitoring, the temperatures are consistently high. 215-225 on city roads. I've never seen it drop below 212 on the freeway, even with the ac on. I tried to bleed any air out my system this morning. Extinct's mod ordered. Let's see if that drops my temps to a reasonable level.