G' day all. Went to work this morning & decided to take the afternoon off - I have been very keen to fit my new radiator & associated bits so I made a start. All going well - old radiator out ( very blocked ) , went to undo thermostat housing so that I could flush system. 2 Bolts were "firm" but loosened easily, 3rd bolt "tight". I wasn't game to apply too much pressure for fear of snapping it off - is that likely to happen ? I can't afford to have my ute off the road too long as I use it for work.Then the in laws turned up & that was pretty much it for the day. My question is can I still reverse flush the cooling system some other way & replace my thermostat etc at a later time so that if the worst happens I can shuffle my work load around ?. Also what is the best technique to bleed the cooling system ? Removed fan & viscous clutch also - fan cracked in lots of places. Sorry my ute is a GU 4.2Tdi. Thanks Old Wal.