Well an OEM Grey thermostat should lower that. I went from 206F down the road in my 99 D2 to 188-193F down the road with the AC on. At idle it was 206-209F, but with the new thermostat it'll go to nearly 200F then slowly drop down to around 193-195F.

If after replacing the thermostat with a grey soft spring unit your temps are higher than what I'm getting replace the fan clutch and the radiator.

Hardest part of my radiator removal/install since I have a 99 was removing the grill. I love how easy an 03/04 Grill just comes right out. It didn't help I also have a Manik brush guard in the way (which I just removed).

 

Well within normal operating range.

 

Would be a fools errand to replace only the thermostat and wipe your hands smiling. Well maybe not entirely as it will help immensely but a complete overhaul of the cooling system would really be doing yourself a favor, especially if your truck still has the red Dexcool antifreeze in the system. That stuff is ridiculous and one thing after another was failing on my ride the first few weeks after I got it. The plastic fittings in the upper and lower hose assemblies were corroding from the inside out and the coolant still looked fine/clear. The hoses were all ****, viscous clutch wasn't pulling air, water pump went out. At least flush that crap out good and refill with green ethylene glycol type, if you don't do anything else. The plastic lines and overflow tank and cap may be getting ready to fail, too. The 220 degree temps and red coolant is disastrous dude. Prepare yourself to be stranded at any time as the damage has already been done.

 

Perhaps fresh off of the lot but not after 12 years, 100K miles! 220 degree temps and DexCool turns everything to ****. I know. Plenty of owners have had cylinder sleeves come undone and engine blocks crack at these temps. A 12 year old Disco with all-original equipment needs to be operating under 200F if any sort of day-to-day reliability is to be expected. Personally, mine seemed very unhappy and developed a paranoia-inducing "tick" at 215 degrees. When I got the temps down under 200 it wasn't making the ticking sound any more so I will have to disagree with you. A Rover V8's survivability exponentially declines as operating temps go up over 200.

 

Just because the thermostat opens at 195, doesn't mean the system runs at that, misconception.

The sleeves slip because the engine overheats, not because it's running at 20 degrees higher than the stat.

What temp do the fans kick on? What temp sends the gauge into the red?


Is there any troubleshooting pages in the manual that state what to do if a certain temp isn't maintained?

My Rover has 200k on the clock and I had it up to 240 Last month after I redid the top half and mine didn't slip.

Yes he could get the temps lower, but if you think these trucks come out of the factory precisely at 195....why didn't Rover install a 180 Stat if they knew 220 was the norm and is unsafe?


Simple, cause 195 Isn't the norm.


Relationship to where the temp sensor is also plays a big part in temp readings.

As long as you monitor it, you should be fine.

 

Acccording to RAVE manual the thermostat opens at 82 °C (179 °F) and fully opens at 96 °C (204 °F). Under normal engine operating temperatures the engine coolant temperature gauge will display in the centre of the gauge. The ECM illuminates the LED when it detects the engine coolant has exceeded a temperature of 121 °C (250 °F) and switches it off when the coolant temperature drops below 118 °C (244 °F).

So everyone here is dropping cash on parts and their stat Isn't even open all the way yet.

 

I hear you shavechevelle, but I figure it would be better to be safe then sorry when it comes to temps. I would rather have it a bit lower in hopes of hanging onto this motor for a bit longer.

I had a caliper seize on me so I'm going to tackle that first.

 

Shane, we all know what these trucks run at from the factory and we all know when the thermostat opens. We all also know that, in our cumulative experience, these trucks are FAR more reliable when run under 200 degrees. Many if us have had head gaskets fail ir cylinder sleeve issues under 230. I know I have with the head gaskets. The temps you're describing, whether that's where land rover said it should run or not, are simply far too hot for our engines. I know that I start getting jittery if my truck approaches 210, I don't like it because I know what comes after. If land rover had designed the cooling systems correctly then they wouldn't be plagued with the rash if head gasket failures on every single truck like they are.

 

Location has a lot to do with setting up your D2 temps. If I was in the NW vs TX I'm sure an OEM thermostat at 190F would be fine. However I live in SETX where the humidity is insane not to mention the heat. I want my D2's running as cool and efficient as possible.

I had one D2 an 02 that ran at 229F for god knows how long before I bought it. I made the mistake of not having my scangauge II on me at the time of purchase. When I finally did get my scangauge II connected I was horrified to see it idling at 229F. The owner had done a lot of work including head gaskets, hoses, waterpump, and the front timing cover gasket. I cringed at the 4.5HR ride home as the lowest I got it down to was 211-216F down the highway... I got it home, and immediately started checking it out. Eventually tracked the problem down to the previous owner did all that work, and didn't replace the one vital part of the cooling system THE THERMOSTAT... (it was still the OEM unit from 02.....) Upon removing it I was amazed at the debris/goo trapped in the bottom of it. The thermostat was completely stuck closed!!!!! It ran great at 229F at idle with no ticking. I dropped in a local replacement thermostat (not the grey one), and my temps went to 193F down the road, and 206F at idle. I also replaced the fan clutch as all it did was free spin.

I'd rather spend $80.00 on an OEM Grey Thermostat, $40.00 in new green coolant, and $55.00 on a new fan clutch than watch a perfect running $$$$ engine cook itself. I think a well maintained D2 engine 4.0 specifically can take higher temps every once in a while without damage, but repeated 229F temps or higher will spell disaster.

I've had an all aluminum GM 5.3L up to 237F (tried a $$$ Efan setup that was a POS), and I lived to tell the tail with no damage.

The highest I'll let my D2's get to is around the 210F range, anything after that = shut her down and let her cool off.