So I decided to buy another Rex, and this time did a bit of research. The other one turns out to have blown seals so its currently in WGT getting an engine rebuild... So that will be back to life shortly.

My new one is running great bar one problem! When you start her cold, coolant light sometimes comes on... The cooling system is fine by the looks of things.... nothing boils, engine is cool, car runs fine. Is it a common problem with the cooling system that the coolant light comes on?

This car has had an engine rebuild only 10k miles ago, the guy I bought it off is the only owner, really nice guy and has kept it well. So I am pretty confident this isn't a dodgy one!

If I wait a little while, or turn the engine on/off, the coolant light generally disappears! Weird?!

 

might be a faulty level sensor. fill it up and burp it. if it still comes on, replace the sensor.

 

Before starting the car (or when the car is cold), open up the coolant filler neck:

http://mahjik.homestead.com/files/FD...iller_neck.jpg

and see if the coolant is at the top or if the level is low. If the level is low, that's what is triggering the low coolant sensor.

 

Have you been adding coolant? Or does it stay topped off but the buzzer comes on? I had a car recently with a faulty coolant lever sensor, only around $20.00 from Malloy mazda. The car would do the same thing as yours, never needed coolant, but occasionally the buzzer would come on. However, it wouldnt only do it when cold it would just do it randomly.