I have a Land Rover Discovery 03; or rather my wife does. I travel frequently and rarely drive the vehicle. A few days back the temp gage started climbing and the engine was running hotter than normal. This is after a week of the vehicle setting un-started. The temperature did not make it to the "hot" stage. (No red light on.) The following day, I started up and headed out, forgetting about the previous night. After a mile or two I noticed the temperature gage creeping higher than normal once again.
I pulled into a local Auto Zone, picked up some coolant and headed back home. By the time I got home, maybe 3-4 miles, the "red" warning light was glowing on the temp gage. The cooling system was "hissing and gurgling" by the time I got home. I checked the coolant reservoir and found it to be low. I waited until the engine was cool then added the pre-mix 50/50. I later took the vehicle for 2 test drives: 1 nice and easy for 20-25 minutes and then another with some hard accelerations etc. for the same amount of time. The temperature indicator stayed in mid-range the entire time. So, I am thinking problem fixed and warn wife to have son check coolant level frequently when I am out of town. Well, the next night vehicle starts to over heat again. This battle has continued for several days. The car starts to over heat some coolant ends up bubbling over and steaming off, I add more coolant, things go well and then the cycle starts again. Last night my wife comes in and says the "red light" came on again during a 4-5 mile drive in town. I checked the coolant level this morning and the reservoir is empty. I re-fill and prepare for a drive to Auto Zone to order a Thermostat assembly. This is the start-up: Temperature needle goes all the way to the top then drops to the bottom. Red light comes on and stays on even though vehicle has only been running 2 minutes. The reservoir is full and I do not see any leaks. I did fix a plastic tube that runs from the throttle body to the reservoir bottle that did seem the have a small leak. Replaced it with a rubber hose. Advice or diagnosis?

 

have the cooling system pressure tested, and stop driving it until you find the problem or you will be looking at a 7k engine. did you attempt to bleed the air out of the sytsem during any of these times?

 

No...I did not know to bleed the system until I stated investigating this issue. I am trying to find a good video to see how to do this...

 

really quite easy it must be done cold.
raise the coolant recovery bottle about 6 inches, it snaps into a clip on the fender .
fill the recovery tank, now open the bleeder screw in the top hose.
let the coolant run out for a few minutes then put the screw back in, refill the recover tank and put it back into the bracket, check the level the next morning.

 

Got it...thanks. Will get it done and report back. I think I will be adopting my wife's vehicle for a bit and giving it some TLC and upgrades....expect I will be spending considerable time seeking advice from members...

 

Well it has been a while since I replied to the message about bleeding the system and the problem with my 02 overheating. (Sorry, but been travelling.) I bled the system as directed and no change. As soon as the vehicle was started, the temp gage needle would still go all the way to the top and then fall to the bottom of the indicator. Red light stayed on from the moment started. So here is what it was. As I mentioned in an earlier post. I had a plastic coolant line from the throttle body that was cracked and broke completely when I was trying to fix it. I had bought a new thermostat assembly on the off chance that it would resolve the issue. When I took the old Thermostat housing out, I found a small piece of plastic from the broken line lodged in the thermostat. Installed the new thermostat, topped off the reservoir, started her up and no issues since. I hope this helps someone out in the future. Still intend to replace all the plastic lines and also do a bunch of other stuff as the weather warms so I will be back. Got a pesky oil leak that needs so attention...

 

Thanks for the update! I have found that the temp gauge spiking and then dropping to cold with warning light on at start-up is caused by an ECT fault logged in the computer. I was helping a friend with his D2. After we got the cooling system sorted, his gauge did the same thing until we cleared the ECT code.