Went for a 3 hr road trip last weekend (Cappadocia, Turkey...off-road paradise!). Just me, the fam and some luggage. While going up some steep, long grades with Cruise Control set at 70 mph, I noticed temps spiking up to 215F (measured via UG). The truck would periodically downshift and tach up to 3,500 rpm for short increments to maintain speed. I slowed to 55 mph and it didn't go past 210F.

While I realize this isn't the optimum speed for a Disco, I also didn't think it would be overheating with no trailer & outside temps around 55F. I have a new Top Hat engine (less than 1 year), new radiator (less than 6 mo), a 180F thermostat, a 3,300 cfm fan and green coolant. Although long/steep mountain roads are a first in the DII, I never had an overheating issue before...not cruising at 75 mph and not in 100F weather.
Is this behavior normal given the circumstances and if not, what's wrong?

 

I wouldn't call 210 overheating. The fan is only just coming on at that temperature. It's a heavy truck, was your AC or heater on? I heard that some of the aftermarket radiators are thought to be less efficient than than the OEM one.

 

The type of 180 Degree thermostat matters.
If you bought a Motorad, I would take that thermostat out and crush it
and throw it away.

Get a genuine Land Rover 180 degree - the grey one in the land rover box.

210 degrees F up a hill is not bad.
You will find that coasting down a hill you'll drop to 180 or so.

I would also make sure the grille and the oil coolers and the A/C condenser are all cleaned out for good air flow.

 

It got up to 215F up the hill at 70 mph...210 at 55 mph. If that's normal, how could this thing ever be expected to tow anything?

-The 180F thermostat is a Motorad. I have a genuine Rover grey one...just not installed. I can do that.
-The radiator is from Genesis Auto Parts...it was $106 new and got great reviews on/off this forum however it is not OEM. I looked extensively for an all aluminum one to no avail, so in my book, plastic is plastic. Not discounting the possibility that it could be the radiator though.
-The fan comes on at 190F because that's what I set it to come on at. It's a temp controlled electric.
-Other parts inside the grill are fairly clean.

 

So you have a 2 1/2 ton vehicle loaded with family and stuff running at 70 mph up a long grade mountain. What would you expect a truck ten plus years old. But yea get rid of the motorad thermo. As for the radiator, well I cannot speak for the brand but in some cases you get what you pay for. To me there are some things that you just do not look for a good buy on, And with these trucks the cooling system is in that category. So, all this aside, what are the temps during normal driving. As we do not know and you are only stating one scenario it is hard to make any kind of real comment about your truck. It really could be as simple as loaded running up hill, or it could be a sign of something else starting to fail. Do you loose any coolant, how long ago did you switch everything over, was it bleed properly. Have you flushed the system lately, or at all. Did you flush before you switched everything out.

 

We travelled regularly up Mont d'Olmes and the D2 TD5 certainly had to work hard climbing the Pyrennee mountains to the top above the snow line. The temperature gauge never showed overheating but it was way above normal. The ambient was pretty low also.

https://www.google.fr/webhp?sourceid...%20d'olmes

 

Normally the rig runs at 188-196F with occasional spikes to 203F on hot days. Coolant system was bled twice in the last year. Once a year ago when I installed the new engine and again 6 month later with the new radiator. I followed DMs write-up on bleeding the system.

 

When engines work harder they produce more heat. I wouldn't be worried about that temperature, but if you want to see if you can lower it a bit, maybe try a bottle of water wetter?

 

Well, then I would keep an eye on the temp and see if you notice anything change. You could be proactive and run a pressure test to see if there is anything there. While you are changing out the motorad thermo add a bottle of water wetter. and see what happens. If this is the only time you have seen this and your daily running shows no other signs of change to running temps you no know that running up along slow grade loaded down your temps run high and not to worry about it.

 

Instead of upgrading to a rover stat, perhaps it's time for an inline mod. I'm just not willing to accept that this truck capable of towing another DII would run 10F from engine damage going up a hill just towing my family (we're not that big!).

I can do pressure test but will take time as I'm very busy. Meantime, any thoughts on the inline mod?