Bleeding cooling system on 520i M50 - BMW Forum

rbooth · 06-16-2009, 05:01 AM

Hi my dad has recently replaced a thermostat as it was causing my car to over heat but not the car does not over heat at idle but the heater is not getting hot and i was wondering how you bleed the M50 engine as i have heard they are a b***ard to bleed

marti5 · 06-16-2009, 06:12 AM

It is probably air in the cooling system. When i change my coolant i always take off the upper radiator hose by the radiator and loosen the upper radiator hose by the thermostat housing and twist the hose up and pour coolant in through the hose to fill up the block, then fill up the expansion tank and bleed the cooling system. Make sure you have your heater on FULL when bleeding the system.

If it overheats agian you may find its not the thermostat but the waterpump on your car its fitted with a plastic impeller, which fall apart over time.

rbooth · 06-16-2009, 07:24 AM

thanks for the advise

could you tell me is there any other bleed points other than the 1 next to the expansion tank

marti5 that car on the reply post look amazing wow

marti5 · 06-16-2009, 07:54 AM

Hi, There is only the one bleed screw and thanks for the comment on my car.

TIP: Always do the fill procedure when cold and have the heater on full heat with the fan on lowest setting, if you have air-con have this switched on.

rbooth · 06-16-2009, 09:00 AM

sorry about this but i have another small problem 2 lol the car idles fine but when u press the throttle it misses between a certain rev range and sometime backfires when my dad was replaceing the thermostat he noticed that the crank sensor was full of oil as i have a leak from the timing cover could this be causeing the missfire???

thanks again for the advise i have got my car as my advar

marti5 · 06-16-2009, 10:08 AM

Do you mean the camshaft sensor, crankshaft sensor is located in the bell housing of gearbox, so Im presuming your talking about camshaft sensor, it may effect it but doubtful ( worth a clean ), more likely a bad plug.

Camshaft sensor controls the fuel injectors amongst other things

and

Crankshaft sensor controls the spark amongst other things

rbooth · 06-17-2009, 03:03 AM

The sensor I mean is the 1 at the front of the engine that goes and I think reads the tooth's on a pulley?? Below the water pump??

this fault is really annoying it on goes lumpy if you press the throttle more than 40% if you press it lightly its ok and revs smooth but if you press it hardish is goes lumpy till it goes past 3k rpm

I hope this makes sense