Land Rover Repair: coolant level and fuel door problem, coolant level, automatic fuel

Question
Hi. I have a 2002 Discovery SE. My engine overheats a lot. I'm having to refill the coolant level every few days. I always know when it's going to happen because the heat doesn't work!
Also, today when fueling up the little plastic thing in the (automatic) fuel door popped out and I don't know how to reinsert it. A diagram would be extrememly helpful but don't have that in my manual. I really appreciate any help ou can give me. Thanks.

Answer
If your truck leaks coolant it will run low and overheat.  I suggest you check for leaks and fix them before the motor cooks itself.  Every overheat incident takes away from the engine's life.  

The clip is tricky to put on, and I don't know of a diagram anywhere, even in the workshop manual.  Perhaps you could find another Disco and look?  I know the first time I confronted that, I broke two or three and then I got it.  Luckily the clips are cheap.