Hi, Im new here to the forum, but have used some of your info and guides lately and all successfully. First let me say, THANK YOU, for having this forum!! We are a chevy and ford family, but my stepson bought a used LR Discovery-2003 about a year ago, and it has driven us NUTS (pun intended) ! So, I'll try to make this short, although it's really not. First problem was about a month or two after he got it. He got in it one day and backed up and almost immediately started to steam and overheat. Checked it out, and the actual water reservoir itself was, brittle and cracked. Well, that was easy enough, replaced it and the hoses on it, as they were dry-rotted and almost broke in your hands. Few more months go buy, starts overheating again. No obvious leaks, but low on coolant, added some--ok for about a week, and his water pump goes out a few days later. So, we replaced the water pump, serptine belt, also ended up replacing upper and lower radiator hoses as these weren't in great shape either. Some time goes by, and it randomly starts overheating again--he pulls the vehicle over calls us. Add water, turn it on and lift the hood, and water, and steam starts to spew out of a part I've never seen. Turned out to be the throttle body. Had people tell us we could/should by pass it, but decided not to, bought a new one, and the new hoses for it, all was well once again. It has been a couple more months now, and today, he started to overheat again. He was idling at the time, and said it went from normal range to red immediately. Thankfully, he had an old chevy that used to overheat on him, and he does know to shut if off as soon as possible,. I don't fear any head-head gasket damage (yet anyway). Starts fine, runs fine, idles fine. Healthy and strong drive to it. Only this time, we haven't lost any fluid, and cant find an obvious leak. Now then, after reading through the forum, I had to FIND what appears to be the thermostat--and Im wondering should we replace that first. Also, Im not certain what the temperature sensor is, and whether we should try that first, or as well. Also, please don't laugh because Im lost on this one, the fan mounted on the radiator--Not sure what it is exactly unless its the engine cooling fan-but looking at it tonight--When I turn the engine on and it's idling, it isn't circulating-is it supposed to be ?-so far--this is where Im stuck at. Its a great little truck, and when we can let him drive it, it does great. I actually like it alot! Im so concerned it is going to end up with engine damage though, if we can't get this all figured out. Im assuming previous owner wasn't doing much pm, and neglected the cooling system since this seems to be the only, all-be-it, constant trouble we are having with it. Sorry this was so long, wanted to give as much info and history as I could on it. ANY advice and help would be GREATLY appreciated!!! (Plus, he is using my truck and I want it BACK ) THANKS!

Mary

 

The engine fan is attached to the water pump, when the water pump fails it can stop turning and not pump water through the engine, and it will overheat.
The fan is plastic, it is between the engine and the radiator.
From what you describe you need a new water pump, no big deal, $100 or so for the part, another hour or so to replace.

 

We just replaced the water pump. The fan Im talking about isn't on the pump--its actually on the front of the radiator --between the radiator and grill of front of truck...

Mary

 

re: the engine cooling fan-but looking at it tonight--When I turn the engine on and it's idling, it isn't circulating-is it supposed to be

In additon to the fan (blades) and the water pump, there is also a clutch between them. If the clutch is shot, the fan may not turn much at all. When the truck is sitting still or in slow traffic, no cooling, rapid heat up. You can test the fan clutch when engine is cold - and engine off. Spin fan by hand and release. Should feel like it is full of peanut butter, maybe turn 1/4 turn when you release. Warm up truck, turn off. Spin and release fan, should stop before one complete turn. If it spins or freewheels, the clutch has lost internal silicone fluid and will not turn with enough force to cool truck. Also, frequently water pump and fan clutch jump off the cliff together. Fan clutch is about $50 (see the tech area for a write up on a Chevy cross over). You said you replaced water pump, so may want to check the fan clutch.

 

The electric fan on the radiator is supposed to switch on at 212 degrees of coolant temp. It has fuse in the underhood box, and a relay that controls it. The electric fan motors do go bad, some members have replaced it with after market complete fan for under $100.

 

ok this is the fan Im refering to. So it is possible then, that it is fine Im assuming?--Like I said, just noticed it tonight and I didn't let vehicle run long at all, so I couldn't be sure of the temp and whether or not it comes on. Will check this asap tomorrow-and the clutch. Providing it does switch on properly, and clutch seems to work, and Im still seeing no fluid leaks, would you recommend a thermostat and/or temperature sensor--Not that Im sure what that technically is, unless it's pretty much self-explanatory--First thing I will do is check fan clutch though. Thanks in advance again!
Mary

 

that fan is also controlled by the AC being turned on, so just let it get up to operating temp and turn the ac on and it should kick on. if not I would check fuses and power to the fan. I would also try to turn the fan by hand to see if it turns freely and smooth.

 

The electric fan runs at certain times with AC on, when coolant hits 212F, and in certain conditions when the truck is turned off and is very hot under the hood. So while truck is running, don't be putting fingers in the electric fan. You can spin that blade with a pencil, it does not have the viscous clutch like the radiator fan.

Could be a thermostat. You changed a lot of stuff, and the thermostat has these little holes in the top of it that let in hot water to make the thermsotat open up. It is mounted in the hoses, not inside the engine block. Could be clogged up with trash.

See attached for electric fan relay in fuse box under hood, it is also fuse 5 in same box.

 

It sounds like you have replaced everything on the cooling system except for the radiator and thermostat. I think that the Thermostat would be a good place to start. If the original thermostat is still on then it is a likely suspect.

Also, it could be a clogged radiator. What color coolant was in it when you got it and what did you fill it back up with? The old dexcool (orange) is known to gel up and clog the radiator if mixed with the green stuff. The radiator and cooling system really should be flushed before switching over to Ethylene Glycol (green).

Check out this link for more information.
"Can I Add the Green Coolant to the Orange Coolant"

Can I add the green coolant to the orange stuff?
As I stated above, the two chemicals of Ethylene Glycol (green) and Dexcool (orange) are not compatible. When mixed together they form a gel-like substance that stops coolant flow and consequently the engine overheats.
What exactly happens when these coolants are mixed?
The coolants chemically react and form a gel rather than a liquid. The coolant stops flowing through the system, clogs up coolant passageways and water jackets, radiators, and heater cores. The water pump overheats and fails due to a lack of lubricant in the coolant. Head gaskets blow, heads warp, and the engine suffers major damage

 

Ok, we just did the check on fans. It doesn't spin freely, and I see what you mean about the feeling of "peanut butter" in it, and it stops at about 1/4 of the way after warming up, turning engine off, and spinning it with hand. The fan on radiator cuts on after letting engine warm up and with ac on--SO im going to assume these are ok....I'll take thermostat off next check to see if it's clogged or perhaps change it out and let you know what happens. Thanks again for any other advice