HELP i have a Discovery 2.5 td5 1999 with a water problem its overheating i renewed the thermostate and the water temp goes up to half way heaters are working fine at about 2000/2500revs stationary .we then take it for drive and as long as the revs are above 1500revs the heaters are working fine but at idle they drop away could this be a water pump problem help me please thanks
hot water man
ps done a head gascet test on it and it comes back ok
