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View Full Version : PROCEDURE: Quick (read: lazy) hydraulic fluid change



Ferret
07-13-2008, 04:29 AM
Requirements:
Syringe
10mm spanner
2* 12" pieces of sturdy wire
2 litres of CHF 11S, contained separately
Can of brake cleaner
New filter

This is how I very quickly changed my hydraulic fluid ~90% without having to go under my vehicle. I know it's lazy and I should be shot for doing it, but it worked - and made a marked improvement to my braking (hydraulic 540 booster) and steering.

1) Shut down the car, while warm and pump the brake pedal about 20 times, or until it goes rock solid. This is releasing pressure from the hydraulic accumulator that's lurking in the system and allows as much fluid as possible to get back into the reservoir

2)Take the cap off the reservoir, and undo the two 10mm bolts holding the filter basket down in place, remove the bolts, spring and the basket

3) Using the syringe, draw out as much fluid as possible, till you uncover a metal plate with a vent in it

http://i11.photobucket.com/albums/a190/Ferret101/Car/DSC00085.jpg
The fluid in this photo was a clean green colour because the photo was taken during reassembly.

The fluid in the reservoir will probably be black as night and smell charred from 15 years use in the power steering system. Mine smelled awful as I drew it out

4) Take your two bits of stiff wire and bend hooks into one end of each. Hook the bits of wire down into the fluid and pull the plate straight upwards... it may resist at first but it's just rubber contact holding it down that needs to be broken.

5) Now comes the fun part, getting the filter out in one piece. Draw out the remaining fluid from both sides of the filter, and reach in and remove the filter carefully. It's fragile so dont brute force it, it may leave one of it's rubber rings behind.

The can should now be empty, DO NOT spray brake cleaner directly into it, but spray it onto a cloth and wipe down the inside of the can with it. You can see all the sediment on the bottom of the can here:
http://i11.photobucket.com/albums/a190/Ferret101/Car/DSC00079.jpg

Clean up the filter by blasting brake cleaner through it for a few seconds, then leave it for 30 minutes on its side to drain and dry. Putting it in some sunshine should really sort it out quickly.

When it's dried, soak it in a dash of the old fluid for a while, just to flush out any remaining brake cleaner fluid.

You should now have a pile of components such as:
http://i11.photobucket.com/albums/a190/Ferret101/Car/DSC00083.jpg

Clean all the metal components up with brake cleaner and it should all come up squeaky clean.

Place the old filter back in, and fill both sides of it with fresh CHF 11S fluid, do not reassemble with the filter dry as the pump will cavitate for the first few seconds of running... we don' wanna be doin' tha gov!

Once you've got a good 2" of fluid in the bottom of the reservoir, you can drop the metal plate back in and reassemble everything, bolting down the basket properly.

Once the basket's in, fill the reservoir with fresh fluid upto 5mm under the edge of the container, drop the lid on and start the car. The level should drop to under the level of the basket out of sight.

Pump the brake pedal repeatedly about 20 times and then take the car out for a drive, to a carpark would be best, snaking down the carpark going lock to lock will flush out all the old fluid into the reservoir.

You should notice things smooth up immediately, the power steering will be much less prone to juddering and hissing.

Give it a week of driving to flush the old crap out effectively and repeat the whole process, this time putting the new filter in.

ProTip: if you're in the UK do not attempt to buy CHF11S from halfords - they want £26/$52US for 2 litres! Go to GSF instead who'll sell you it for £5.25+TAX per litre

yaofeng
07-13-2008, 07:22 AM
Don't think it will work fot the US model. The US model has a bottle in front of the coolant pump. The space shown in your picture is occupied by the brake booster and the ABS unit.

There is a plug in the bottom of the PS pump you can remove with an allen wrench to drain all fluid, however.

Ferret
07-14-2008, 02:22 AM
There is a plug in the bottom of the PS pump you can remove with an allen wrench to drain all fluid, however.

Yeah, however I suspect that the filter contents wont drain properly if you do it that way around! (And it means lifting the front end of the car, which I was deliberately being too lazy to do :D )