[BMW2Hart]

Just passed 50K miles and want to flush the system myself. Anyone out

there performed such a task yet? If so, please pass along info.

Thanks...

[GMWNashville]

pretty difficult..the fact that you have an electric waterpump which is what is used to bleed the system..however...there is a way to get the waterpump to go into bleeding sequence i just forget it off hand...we always just use the gt1..

[voltron1011]

Instructions for venting cooling system:
1. Switch ignition ON (without starting engine)
2. Set heater to maximum temperature and turn fan down to lowest speed.
3. Press accelerator pedal for 10 seconds to floor. Engine MUST NOT be started!
4. The venting procedure is started when the accelerator pedal is pressed and takes approx. 12 minutes (electric pump was activated and shuts down automatically after 12 minutes).
5 Then top up fill level in coolant expancsion tank with 100ml above MAX line.

[bimmerque]

Originally Posted by voltron1011

Instructions for venting cooling system:
1. Switch ignition ON (without starting engine)
2. Set heater to maximum temperature and turn fan down to lowest speed.
3. Press accelerator pedal for 10 seconds to floor. Engine MUST NOT be started!
4. The venting procedure is started when the accelerator pedal is pressed and takes approx. 12 minutes (electric pump was activated and shuts down automatically after 12 minutes).
5 Then top up fill level in coolant expancsion tank with 100ml above MAX line.

good start, but it seems that a few steps my be missing in your example, go deeper in your discussion!

[voltron1011]

I pulled that info off of the BMW CIS dvd... I haven't actually done it myself (yet)...

[txusa03]

I dont understand what step 4 means by the word venting? In all 5 steps, where is the step for draining the existing coolant fluid and where is the drain plug?

In other word, step 5 says to top off with new coolant but where is the step to drain the old coolant?

[FrankoQ]

subscribed.

[voltron1011]

Originally Posted by txusa03

but where is the step to drain the old coolant?

This is procedure assumes that the coolant has already been completely drained from the car..

I believe the only thing you need to do is:
1. Drain coolant from radiator drain valve.
2. close drain valve, and fill up the radiator up with a 50/50 mixture.
3. close radiator cap, and perform venting process (mentioned above) to ensure that the system is completely full.
I'm guessing the venting procedure is mainly for circulating coolant to the other parts of the engine, and topping off the expansion tank as the level goes down?

[npolite]

Please forgive my inexperience with the BMW design but couldn't you just start the engine with the heater on high and leave the radiator cap off until all of the air has been purged from the system? I usually just do a drain in fill on most of my other cars. Yes it doesn't get everything in the engine block but I just do it again a few weeks down the road.

[voltron1011]

Originally Posted by npolite

Please forgive my inexperience with the BMW design but couldn't you just start the engine with the heater on high and leave the radiator cap off until all of the air has been purged from the system? I usually just do a drain in fill on most of my other cars. Yes it doesn't get everything in the engine block but I just do it again a few weeks down the road.

I think the problem with that is that the system is completely hot and pressurized at that point, so you wouldn't be able to add coolant without steam shooting everywhere... Remember, that these systems work under extreme pressure.
With BMW's version, the engine never starts, but everything in the cooling system still opens up (heater core, thermostat, etc) and the waterpump is running... Thus, you can add coolant to the expansion tank safely.

[npolite]

Originally Posted by voltron1011

I think the problem with that is that the system is completely hot and pressurized at that point, so you wouldn't be able to add coolant without steam shooting everywhere... Remember, that these systems work under extreme pressure.
With BMW's version, the engine never starts, but everything in the cooling system still opens up (heater core, thermostat, etc) and the waterpump is running... Thus, you can add coolant to the expansion tank safely.

I can't comment on the BMW cooling system but as far as with the few Honda's I have owned (they don't have expansion tanks) the procedure that I have mentioned has worked for years without any problems. Maybe I leave it on to the point where the car warms up enough and any air exits from the reservoir?