coolant bleeding

[320iAN]

any tips for bleeding through the coolant for when i flush, fit a new thermostat & refill the system?

looking through the M42 owners club a few folk have recommended that a small hole is drilled to the top face of the new thermostat to help get the flow moving past the thermostat until it reaches temp.

what ya'll think?

thanks

[rix313]

Can't think why would you want flow past the thermostat before it's up to temp? Seems abit odd tbh what size hole do they recommend? IMO if the hole was to be so small it doesn't effect warm up surely it's pointless and if it's so big that it effects warm up you don't want it strange lot the yanks Maybe I'm missing something.

When I changed all mine I didn't do it the cleanest way. I just poped off the hose at the bottom of the header tank and tried to catch as much in a container as I could I believe there is a small blue drain plug in the bottom corner though which will be a much smarter way of doing it

When it comes to bleeding it make sure you have the cabin heater on full blast on full temp to get the water circulating fully around the system. Next to the filler cap is a small plastic screw this is the bleed screw. Keep the water topped up in the header tank and when it's up to temp undo the bleed screw to release the air. You should keep it open until just water runs out then nip it back up. While doing it keep checking the temp gauge on the dash, check the radiator is getting warm starting from the top hose and progressing down to the bottom hose.