my disco II overheated ont he turnpike. By the time i noticed it, i wasn't in a place to pull over so it got pretty far into the red and light came on. Pulled over, let it cool down and got enough water to make it the 5 or so miles home. turn out by coolant reservoir is cracked where the throttle cable heater hose attaches. a day later and full of water, when i start the engine, the temp gauge doesn't move and red light is on. was there damage to the thermostat so that the temp gauge isn't working?

 

Did you get a new coolant reservoir tank?

Did you bleed the system after filling it back up? (if you didn't bleed it then you probably have a huge pocket of air around the temp sensor)

 

no not yet, this happened last night. ill get a new one on tomorrow.

 

The temp sensor is top of engine, between AC compressor and alternator. If unplugged, it will make gauge read low and light on. Or sensor could be burned out by your adventure.

Now for the bad news. The heat gauge is built to point at 50% from 130 -240f so you drove for some distance as things started getting hot. By the time you buried the gauge and turned on the red light, temps were at about 285 degrees. Head gaskets can go out a whole lot cooler. Cylinder sleeves can break loose and start ticking. Heads can warp.

If you get out of this with just a coolant jug and maybe a sensor you should buy a lottery ticket.

 

^That's what I'm hoping did not happen, but there is a good chance it may have.

 

I just replaced my water pump and I got hot this morning. It did get hot enough to overflow out of the reservoir tank, but I didnt drive it long enough to do any damage. I'm wondering if maybe I have a bubble. How do I get any bubbles out?

 

OP; I had the same problem myself last week I got the new bottle and new throttle body hose at AB the bottle was only like $69.00.
throw the bottle and hose on and hope for the best.

 

Get ready to do head gaskets. I left my exp tank lid off one day. It overheated and 2 months later Head gaskets. I had just had them done the year before. It's like Buzz said by a lottery ticket if you don't need them soon.

 

chataf - unbolt the coolant jug, hold it up high as hose will reach and open the bleeder valve on the T. Engine off. Keep adding fluid until no more bubbles come out. Messy. Don't stop at first few bubbles.

Also, without fail, check your serpantine belt route against the manual. Don't guess.

As for "got hot", if you have only the factory gauge that could be bad, as it points at 50% from 130-240 ish. See pix below, 2 trucks, 2 temps on OBDII port, same on oem gauge. You really don't know much from the factory idiot pointer system.

 

Check Rave or Google "Flush Radiator Discover II" there are a hundred explanations---- All different.
The way I did it;
Engine off -system cool
Elevate the Expansion tank higher than the Bleed Screw. remove bleed screw . Keep expansion tank full or close to full. When water starts to come out bleed screw , Let it run out for 30 secs or a minute. Keep coolant in exp tank or it will suck air into the system. Put bleed screw back in while coolant is still running out. This is sort of the Disco Mike method.

Works for me I just did it yesterday