Timm's E31 840ci CHF11S Power Steering and Brake Booster Oil and Filter Change

There are two contentious issues when changing the power steering fluid: The actual type of oil to use, and the correct filter part number. The first is pretty easy, on the 840ci, the type of oil to use is written on the cap - and is CHF11S which is available from many sources. The second, the correct part number is contentious because RealOEM shows the wrong part. The correct part is 32411128167 which is specified for the V12's but is the correct part for the V8's as well:

The filter and filter seals are shown with their part numbers below:

I'm not changing all the fluid as I did this a few months ago, but was armed with the wrong filter at the time. So, I'm going to slurp out the fluid using a couple of syringes. I will use a 100ml one to get most of it out, and a smaller one with a length of silicone pipe to get the rest out. Have a microfibre cloth to hand and a container to put the old CHF11S oil in for disposal:

The mesh is held in place by a pair of 10mm nuts, so slurp out some oil and then measure how far down the threaded shaft the nuts are fitted so that you don't have to guess when re-fitting and then wind off the nuts:

Lift the spring out, lift the filter out and slurp more fluid out. Use the small syringe and tube to get all the fluid out and you will see the filter:

To get the lid of the filter off, use a couple of metal tent pegs to hook underneath it:

Once the lid is out (no intermediate photo's as too much oil around to use the camera), the filter itself can be lifted out by hand:

I was immediately concerned that I had the wrong filter again, but the filter is fitted with rubber end-pieces which can be peeled off:

.....and fitted to the new filter:

To reassemble the filter in the reservoir takes a bit of jiggling, especially getting the lid and filter to centralise, but it can be felt getting into the correct position. Fit the collar and then the mesh filter, fit the spring and wind the nuts back down to the correct position. Refill with fresh CHF11S and then refit the lid and you are done.

I have not mentioned pressing the brake pedal lots of times to get the fluid from the pressurised container (bomb) as I did not need to change the fluid. But if draining the system as much as possible, press the brake pedal lots of times until the pedal becomes hard as this removes the pressure from the bomb and releases the fluid into the reservoir.

All done, time for a cup of tea


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