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Master Cylinder Replace & Bleeding

Posted: 21 Jul 2024, 17:49
by Dennis_87
Evening all!

It appears as if our Clutch Master Cylinder is leaking fluid in to the drivers foot well, which is pointing towards replacing it.
Much to the amusement of my brother & dad, I'm going to attempt this myself. :shock:

The actual replacement looks relatively straight forward, if not a bit fiddly. Is there any advice/tricks to look out for?

My main concern, however, is bleeding the system afterwards? I've watched one tutorial video, but it didn't do a great job of explaining what to actually do. Also, the bleed screw on the video is different to mine (pics below - first pic is tutorial video, second pic is our van).

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Does anyone have an idiots guide to bleeding the newly fitted master cylinder, please? Will I only need to bleed the master cylinder, or will it need bleeding from the slave cylinder too?
Apparently there are instructions in the Haynes manual, but I don't have one and can't find an online version.

Thanks in advance for your help!


 

Re: Master Cylinder Replace & Bleeding

Posted: 21 Jul 2024, 18:20
by Aidan
You don't bleed the master you bleed the slave
So clamp the rubber feed pipe before removing the master cylinder
Make sure brake/clutch fluid reservoir is full once the new cylinder is fitted and rubber hose is unclamped, then open the bleed nipple on the clutch, let it bleed under gravity, it's good to use the rubber hose on the nipple and clear hose and empty pop bottle trick to minimise mess and prevent air being introduced at the bleed nipple, once fluid is coming through without air bubbles close bleed nipple and check operation of clutch; be careful when starting engine to ensure gearbox is in neutral, don't just drop the clutch pedal assuming the clutch is clear in case it isn't and vehicle lurches on the starter
check fluid level in reservoir before driving to ensure you haven't compromised the brakes, ditto don't let the reservoir run dry while bleeding

Re: Master Cylinder Replace & Bleeding

Posted: 21 Jul 2024, 18:32
by silverbullet
And neutralize any spills with methylate spirits, soak a rag in the stuff and wipe the rubber mat down, if there are any splits it will be underneath and attacking the floor paint.