How to: Bleed Coolant System (M54)
- Thread starter andrewr
- Start date
simonlpearce
Senior member
Keys to position 2, heaters on highest heat, fan on lowest setting. Pour in new fluid.
Of course you have needed to remove the old stuff first via the drain plug on the rad and if you can be bothered there is another on the block which i expect is a ball ache to get to. The amount of fluid left behind wont affect the running of the car as it will only be a small percentage, just give yourself a little more coolant in the mix when refilling to compensate.
If you can, it helps to park the car facing up hill too so the air rises.
Lastly when its full, take it for a run then come back and allow it to cool and check your levels. Fill up as necessary.
Of course you have needed to remove the old stuff first via the drain plug on the rad and if you can be bothered there is another on the block which i expect is a ball ache to get to. The amount of fluid left behind wont affect the running of the car as it will only be a small percentage, just give yourself a little more coolant in the mix when refilling to compensate.
If you can, it helps to park the car facing up hill too so the air rises.
Lastly when its full, take it for a run then come back and allow it to cool and check your levels. Fill up as necessary.
Thanks for the quick reply. The fluid has recently been changed but I suspect some air in the system as the coolant level is fluctuating greatly despite there being no leak.
Is there a simple way of removing the air out of the system without having to replace all of the coolant?
Many thanks,
Andrew.
Is there a simple way of removing the air out of the system without having to replace all of the coolant?
Many thanks,
Andrew.
simonlpearce
Senior member
Park it facing up hill, or get the front end on ramps/axle stands then put the keys in position 2, heat on full, fans on low, undo bleed screw and it should self bleed. Refill until the expansion tank is half full (to the line). Take it for a run and make sure it gets to full temp and you are getting full heat from the blowers, which basically means the water is properly circulating and there is no air blocking the heater matrix. Also keep an eye on the temp as it should get to half way.
Get home allow it to cool and re-check then refill as necessary.
Hope that helps.
Get home allow it to cool and re-check then refill as necessary.
Hope that helps.
Following the advice above, this seemed to have no influence on making the coolant system cycle the fluid. As the M54 water pump is belt driven, I don't see how it could work with the engine off?
Anyway, I bled the system with the engine on, but I'm still getting the intermittent issue of the coolant light coming on and off during a journey.
When checking the coolant level at cold, it's at the maximum level, so I can only think that there's an issue with one of the sensors as there doesn't appear to be a leak in the system and the coolant level continues to remain at max.
The only other issue I can think is that the coolant looked very pale, almost clear, so I think it's time to flush the system completely and replace all of the coolant as the colour would suggest much more than 50/50 ratio of water to coolant. Could a higher ratio of water in the mix be causing the coolant to boil over and set off the coolant light?
Andrew.
Anyway, I bled the system with the engine on, but I'm still getting the intermittent issue of the coolant light coming on and off during a journey.
When checking the coolant level at cold, it's at the maximum level, so I can only think that there's an issue with one of the sensors as there doesn't appear to be a leak in the system and the coolant level continues to remain at max.
The only other issue I can think is that the coolant looked very pale, almost clear, so I think it's time to flush the system completely and replace all of the coolant as the colour would suggest much more than 50/50 ratio of water to coolant. Could a higher ratio of water in the mix be causing the coolant to boil over and set off the coolant light?
Andrew.
