I have a 03 Disco. Recently, while my wife was driving the truck, the hose that runs off the top of the Thermostat got jarred loose. I had changed out the water pump weeks before so I think it coming loose was probably my fault. Anyhow, needless to say she ran it hot, as it dumped it's coolant out from the detached hose. It happened a block away from my house so hopefully no permanent damage.
I replaced the thermostat because it was horrible looking and thought it would be good idea. Now the truck starts up nice, but.....
Questions:
1. The temp gauge upon start, flies up to the red light (which is now on permanently) and then goes down to beyond cold and stays there. Won't move. Haven't tried driving it yet though. Will driving it a bit help the temp gauge? Would the ECT sensor be affected by the changing of the thermo? The temp gauge and the detached hose were simultaneous issues, they happened at the same time rather.
2. After replacing the thermo i refilled with coolant. I turned the truck on, letting it warm up a bit to see if the temp gauge would start to work (which it didn't) and found that if I removed the coolant bleeder screw at the intersection of the two radiator hoses no water would come out. If i had filled the coolant and closed the cap on the overflow tank, but left the bleeder screw off, wouldn't water come out of the bleeder screw hole upon starting the truck? Because none is coming out.
You guys have helped me before and I look forward to any help you can offer on my new issue.
I have recently changed out the water pump, coolant overflow tank, throttle body heater plate gasket, various coolant hoses and spark plugs.
Thanks in advance guys.
Rob

 

Sounds like there isn't enough coolant to touch the sensor. DON'T DRIVE IT.

When it's cold, open the bleed screw. Detach the expansion tank (it pops out if you lift up form the back. Raise it up so its higher than the top hose. Keep filling slowly until you get a steady stream of coolant out. Close the bleeder. Put the expansion tank back.

At that point, you're at least close. See if the gauge starts working. Turn the heater on full blast. You probably still have some air in the system. If the gauge works, get it up to temperature. Rev it a bit to make sure the pump is circulating well. Just a bit on occasion, no need to go crazy. Then shut it down and let it cool off. Fill the expansion tank up to the mark and you should be all set if nothing else is wrong.

 

Sounds like you need help bleeding the system so you can then run it to verify if you have damaged a head gasket.
PM me your number and I'll be glad to walk you thru what to do.

 

Thanks guys for the quick responses. Did the bleed Mike, done it before when I changed out the pump and the throttle body heater plate. Found out quick that if you don't bleed right the truck will get hot.
Did the bleed and still the temp gauge flies up to the red light then back down and stays down.
Coolant temp sensor? Where is this located? Searched it but got differing results. My truck is 2003 Disco2 SE7, beyond the BAD oil-pump VIN range.
Searched Atlantic British for replacement Coolant Temp Sensor and all i found was one that goes on the bottom of the Rad. Is this the only Temp sensor for my truck?
Thanks
Nitefall

 

It's right here:

 

Thanks DarylJ, i would've never found that it.