Hello all, I have a 2003 Disco 2, with 155000 miles on it. I love the vehicle, but i'm about to loose it.

The truck overheats when the engine is under load. Going uphill, or running the AC.

I've changed the thermostat, water pump, AC condenser fan, and the viscous fan.

There is no coolant in the oil, and no white smoke.

If it begins to overheat, I shut off the AC, and it returns to normal. If I don't catch it in time, turning up the heat to full blast brings it back down to normal temp.

Any ideas anyone...your help would be greatly appreciated! I don`t want to end up scrapping this old girl, especially if its something stupid....

 

These radiators are known for getting blocked, especially if you are still running Dexcool (orange coolant).

I have read that you can test it by

a. buy one of the laser thermometers
b. start truck and run til thermostat opens
c. use laser thermometer to measure temps around the front of the radiator

I think the rule is if the temps vary by >5 degrees you have a blockage of some sort.

 

I'd add to that to measure top to bottom, and a difference of over 10F indicates lower rows are clogged up. You turning on the heat and getting temps down indicates the main radiator is not performing 100%.

Forget about flushing it, that should have been done every 30,000 miles or two years. Forget about a rad shop "rodding" out the calcium buildup, plastic side tanks are too brittle. The calcium will be like in this picture, row after row, and it goes all the way across. Eventually gets to the point that air flow through center of rad is cool (less hot water flow) and the viscous fan won't respond like it should because the faceplate is not above 170F.

Replacement rads run $150 - $300 depending on source and quality. Put in a 180F Land Rover thermostat (not motorad), about $60, at same time.

Pix of sludged radiator, and of D2 with 180F stat headed to the desert. Don't trust the factory temp gauge, it shows 50% from about 130 - 240F. Use a scanner, Ultra Gauge, or bluetooth to Android app for a smarty phone.

 

At your mileage the radiator, if original, is shot. That being said, replace it and add a 180 degree t/stat and new coolant pressure cap, then test and replace your viscus clutch, should be twice as hard to spin when hot over cold.

 

Do the trifecta.

Thermostat - 180 degrees from Rover. You did that.

Hayden HD fan clutch. Replace this - no matter what. Don't spin it and try to 2nd guess it. It is shot. Replace it.

Radiator - replace it.
Rockauto.com has them very reasonable. $200 about shipped to your door.

Since I replaced all three - I never worry about temps any longer.
Don't have to.