Changing clutch fluid

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duncanh

Active Member
Joined
Aug 31, 2005
Messages
242
Location
Wiltshire
Car
BMW 520d SE F10, formerly c220cdi estate (for 12.5 years and 345k miles), before that w124 and w210
I have a c220 cdi W203 (2002). It is time for me to once again change the brake fluid (last done 2 years and 60000 miles ago).

I have recently realised that the clutch is hydraulic (I never guessed, thinking that as there is only one reservoir that the clutch must be cable operated).

I realise that changing the brake fluid gets new fluid into the reservoir, but what about the old fluid in the clutch pipes and slave cylinder? Does it stay there, or does it get mixed with the newer fluid in the braking system?

In other words, should I change the fluid in my clutch system? If so, how do I do it? Is there a bleed valve on the slave cylinder (if I can find the slave cylinder that is!)?

I have seen posts from IBW about connecting clutch bleed nipples to brake bleed nipples with a length of pipe to bleed the clutch, but I am hoping to avoid this by just changing the fluid without introducing any air that needs to be bled out. Also, does the IBW method apply to my car, or is it just 124s?

I normally use a Mityvac to bleed/change the brake fluid, i.e suck out the old stuff through the bleed valve. Will this work for the clutch? I can't see why not, but what do I know?

Or should I leave well alone, change the brake fluid and forget about the clutch.

After 155,000 on the same clutch, maybe I am worrying unnecessarily, there may be a bigger problem round the corner.

Any advice gratefully received.

I was wondering whether to post this in Engine and transmission, or brakes section. Seemed a toss up which. I guess I would get flamed if I asked for a clutch section. I think I have one of only 8 Mercedes cars ever built with a manual gearbox.
 
I would cross connect from a recently flushed brake caliper, and push fluid from the brake system back through the clutch system, finally sucking out most of the dirty fluid from the brake reservoir and topping up with fresh.

On a few occaisons, I have run into trouble trying to bleed a hydraulic clutch as you would a brake system, and to recover, I've had to back-flush. It's beter just to begin by back-flushing the fluid.
 

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