I have a 2000 DII, i keep losing coolant but i cant find the leak.Originally it was overheating only when it was in idle. i realized that condenser fan was not coming on so i replaced it .I replaced the thermostat and the bleeder screw broke and was leaking so i replaced it, also in one of the pictures ive attached it was leaking at the attatchment connecting the engine to the T on top,i just cleaned it well with a brush and used silicone to reseal it. About every four days its running low on coolant and i cant find a leak or not seeing anything on the ground.i also checked the oil and it doesnt seem to be milky or anything ,so im guessing its not the head gaskets? I dunno...Im confused. I appreciate any help

 

Put in one can of Barr's leaks.
This stuff actually came from Jaguar for the XJS engine.
This will probably help you get by until you can tear into the engine.
I put it in my 1997 for a time and it helped the coolant issues.

Turned out on my 1997 the coolant was going into the catalytic converters and burned out BOTH my cats.

So, put in the Barr's leaks.
Or replace the head gaskets maybe.

---
Here is a clue-.
Most of the leaks happen when you pull in the garage and then
the engine is cooling down.
10 minutes after you pull in - keep looking for dribble on the floor every 1 minutes.
It will show up if leaking externally.

 

1. If you don't have a scanner, get one so you can watch temp more closely, the stock heat gauge will point at 50% until you are already overheated.

2. Coolant loss can be external (head gasket, valley pan gasket, throttle body heater, front cover gasket, water pump gasket, water pump, lots of hoses, and wimpy coolant jug cap, which can vent while driving and you never know it. You can zip tie a paper towel around the coolant vent hose, to see if it is getting soaked from bad cap. You can borrow/rent a pressure tester from parts store, pump up to 15 psi and wait 30 mintes for leak to show up.

No milky oil and no white smoke out exhaust is a good sign.

 

My head gasket leak was dripping on the exhaust pipe just in front of the O2 sensor, never saw a drop for a long time till it got worse. I rented a leak tester from parts store , I found a small hose leak that wasn't leaking until I used the tester. Put with the engine cool i pumped the tester up to 15 psi and it held pressure. THe head gasket would seal back up when the engine cooled. I finally found it when I started doing the head gaskets. IT wes in the front behind the AC compressor bracket. Hard to see.

 

So, how mechanical are you? How many miles on the engine and have head gaskets ever been done?
If you can do it, do a coolant pressure system test to 18 pounds for at least 15 minutes. Don't do anything else, especially adding s stop leak, which is only a bandaid and will fail.
Let us know what you find in the form of a coolant leak so we might be able to help.

 

I agree with Mike.

First you want to fix the leak, then see if it's still overheating.

Go to advance auto parts and get a coolant system pressure tester. It requires a $200ish deposit that you get back when you return it.

Fill the coolant system up and bleed it. Just google "land rover discovery coolant bleed".

Put the pressure tester on and pump up to 15-18 psi.

Now examine every part of the cooling system. Lay down under the truck and look at the underside of the heads, the radiator, and look for drips.

With a leak as large as yours, you should be able to find it.

DO NOT DRIVE YOUR TRUCK TIL IT IS FIXED. OVERHEATING THESE TRUCKS CAN EASILY CAUSE $2000-$6000 WORTH OF DAMAGE.

If you find the leak and don't know what to do, take pictures and post them here.

 

Losing coolant is not good, and should be fixed. However, with it only overheating at idle, you eliminate a few things. The list narrows down to and air pocket in the system(caused by whatever leak you have), reduced air flow through the radiator (bad fan clutch, partially blocked air passage), water pump going out and not flowing well, restriction in the cooling system (have you already used a 'stop leak', seen several radiators with internal restriction).
If you run the truck until it gets hot, not overheated just normal temp, then go under it and look, it's similar to having a pressure tester on it, and you should be able to see something. Check the back of the engine, under the heads. If you go under the car when hot, be careful of things that are hot, second degree burns aren't very fun.

 

If you need the AC fans to keep it cool when the AC isn't on then you have a faulty cooling system. Keep that in mind after you locate and fix the leak(s).

 

...had problems with leaks at the throttle body heater, reservoir and everywhere there is hard plastic hose, including the 't' which you already replaced. if you're still using dex it's easier to see dried leaks as orange crud at clamps and connections.

they're right when they say don't overheat it at all. and of course that the dash gauge is slow to alert you to a problem potentially causing damage before you have any idea.

 

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Im definitley not a professional but I know a little bit, I hate paying a mechanic so I fix my vehicles. This is the first rover I've had so I'm not as knowledgeable about it as I am with domestic vehicles.it has 105,000 miles on it, I've never replaced the gaskets on it but I'be only had it for about 6 months