Hyper_545i

I got an active steering malfunction on my 545i yesterday on the way to work. I checked the fluid before heading home (engine cold) and found it was indeed low. I bought some Pentosin CHF-11s from the local stealership for 38 bucks! I know it can be bought for half the price but did not feel like waiting for it to come in. I thought of just topping it off but then realized it would be a good time to flush the system. I used the turkey baster method and was able to pull out about a liter from the reservoir. I topped off to the correct level and bled the system.

I was hoping to flush it a few times but only had one can of the Pentosin. I figured it was better than nothing. I will order another can or two and will flush again on my next oil change. Question is, how many liters does the system actually take?

This is probably one of the most overlooked maintenance items.If you have not done this, please do yourself and your E60 a favor and look into it. I doubt my fluid was ever changed. It was very dark! Consider this insurance for you power steering pump, AS and ARS Systems.

BimmerFan52

You are not really flushing when you siphon the contents of the reservoir. It is better than nothing, but all of the fluid in the lines and valves are untouched. And for total maintenance you also should replace the reservoir which has a permanent filter built into the bottom of it.

Attached is the ZF procedure for flushing.

Hyper_545i

BimmerFan52,

Thank you for the info! I found out after the fact the PS Reservoir should be replaced. I will definitley look into this for my next service. I agree with what you are saying in regards to syphoning the system, however, if the fluid is drained and bled several times, eventually the majority of the fluid will be replaced correct? My plan was to continue the process until the reservoir is clean.

BimmerFan52

It's up to you. My steering rack was recently removed for examination so I directed the shop to use the ZF procedure (I supplied it to them) as well as replace the reservoir, but if you don't feel comfortable removing the lines to the cooler then the siphon method is certainly better than nothing. After each siphon and fill you get progressively closer to totally new fluid. The only downside is each time you are removing fluid you are removing both old and new. I would still replace the reservoir (not difficult) and wait to replace the reservoir until you have siphoned the reservoir and are ready for the last addition of new fluid.

It is a similar situation to draining and refilling the transmission twice (the method I and most people use) as compared to flushing the trans by disconnecting the lines at the transmission cooler and running the car while picking up new trans fluid from one bucket using the return line and dumping the incoming line into another bucket. The torque converter holds almost half the total system fluid and you end up replacing only a portion of the fluid each time. Two drain and fills get you to the 75-80% range of new fluid.

CVTBenhogan

You should drain from the hose underneath the car.

I replaced the reservior/filter and it was fairly easy using the baster. Then drained the line.

I can't recall but maybe capacity is 1.5 liters. $15 a liter at Kelly's Auto.