Coolant drain & flush on M54 Unit

[Ade33]

I think I'm correct in saying that if you simply pull the bottom hose to the radiator only about half of the 6.5L of coolant will drain.

In order to do the job properly there is apparently a plug on the block that needs removing to drain that

Has anybody managed to locate it and if so how di I get to it.

Once new coolant is put in whats the procedure for correctly ensuring there is no air in the system/bleeding??

 

[Delk]

I cant say if it is required or not but the plug you are talking about is on the block, under the exhaust just forward of the motor mount if I remember.

 

[Fender2004]

On my M52 engine I have raise the front of the car on ramps, and then turn the top hose 90 degrees so you can pour coolant in to fill then engine up, then fill the radiator up as well reconnect the top hose, and I've never had a problem. When I fill the radiator I had a funnel with a 90 degree bend in the filling spout, allowing me to fill the radiator slowly and there isn't coolant all over.
Hope this helps.

 

[Nodzed]

Coolant Vacuum

If you get one of these it's a breeze and will totally evacuate the system and refill it without the chance of airlocks. Used one recently and I was well impressed. It's amazing what this will pull out from a drained system including the heater matrix etc.

 

[Fender2004]

Coolant Vacuum

If you get one of these it's a breeze and will totally evacuate the system and refill it without the chance of airlocks. Used one recently and I was well impressed. It's amazing what this will pull out from a drained system including the heater matrix etc.

I think I might look in this, as always every day is a school day.

 

[DrWong]

I loosened this plug when I renewed the thermostat. As above and according to Bentleys, it's on the exhaust side by cylinder two. I think I had to use a ring spanner to get to it.

Refilling also just followed Bentleys, i.e. add coolant to expansion tank til it spills from bleed screw, tighten bleed screw, turn heating controls to full warm, turn on and warm engine, loosen bleed screw, add coolant to expansion tank until no air is in the coolant coming out of the bleed screw, tighten screw and replace expansion tank cap.

I didn't do the raising the front up bit and it went fine. If you spill coolant on your exhaust manifold, it will create copious amounts of steam as you warm the engine and terrify you, as it did me.

 

[Fender2004]

Glad you got it sorted

 

[Nodzed]

I think I might look in this, as always every day is a school day.

Its worth a look as just draining leaves a lot more in the system than you would believe, Im talking litres.

 

[ChrisD]

Its worth a look as just draining leaves a lot more in the system than you would believe, Im talking litres.

This looks very interesting. I understand the vacuum fill procedure but I have a couple of stupid questions:
1. How is the equipment used to drain the system? With vacuum or using +ve pressure?
2. Could it be used with a small compressor (e.g. tyre inflator) or does it need a workshop airline to get the necessary vacuum?

 

[Ade33]

I loosened this plug when I renewed the thermostat. As above and according to Bentleys, it's on the exhaust side by cylinder two. I think I had to use a ring spanner to get to it.

Refilling also just followed Bentleys, i.e. add coolant to expansion tank til it spills from bleed screw, tighten bleed screw, turn heating controls to full warm, turn on and warm engine, loosen bleed screw, add coolant to expansion tank until no air is in the coolant coming out of the bleed screw, tighten screw and replace expansion tank cap.

I didn't do the raising the front up bit and it went fine. If you spill coolant on your exhaust manifold, it will create copious amounts of steam as you warm the engine and terrify you, as it did me.

Can you remember whether you had to get underneath the car to get access to the plug to remove it or could you do it from above?

 

[Delk]

I am pretty sure you need to be under the car to reach but not posative. If you have AC it will be more difficult from above. If you dont and the air blower is already removed you may have enough room.

 

[Ade33]

Thanks that makes sense.. I will take a look

Like another poster I'm interested to know how this piece of kit that pressure flushes it out works and any experiences of using it on a Z3

 

[DrWong]

Can you remember whether you had to get underneath the car to get access to the plug to remove it or could you do it from above?

Pretty sure I did it from underneath