I just fixed the expansion tank in my 02 disco2 because it had a leak. It leaked a good couple weeks before it started to overheat...of course, I didn't drive it hot and the temp light luckily came on a few yards from the house....anyways, my heat isn't working now...whyyyyy?!?!?! I refuse to panic just yet cus I'm thinking thermostat

 

you need to bleed the air out of the cooling system, the heater core is the highest point so air gets trapped in there

 

Overfill the reservoir and drive the car for a few days. The pressure from the excess coolant will displcae the air in the heater. At least it did for me. Once you think all the air is gone, top up the coolant as necessary.

 

Found a leak in expansion tank....gonna have to seal t until new tank gets here...the one I put on was from another Rover...let it set 30mins before driving it up the block and temp gauge started to rise

 

yeah, i wast to sure how a repair would hold up, the tanks get awfully brittle.

If it were me , When the truck is stone cold I would raise the recovery tank as high as you can get it.
fill it to the maximum and open the bleeder screw in the top hose.
Be prepared to lose coolant, you are going to have to force all that air out of the core, so if it stops a a few second don't cap it.
could take a minute or two. then take it for a ride with the heater turn up and check it the next morning

 

Hate to sound stupid but can u tell me how to do this effectively? This is the second Rover we have owned and from experience, I'll be doing most of the repairs myself this time...

 

see above

 

OK...I'm going to try that....anywhere you know I can order an expansion tank?

 

How would one tell if thermostat sticking?

 

new one are all over ebay.

one of the parters at the end of my signature may have a good used one.

I would go for the good used one, i bought a new one on ebay and it was paper thin.