Clutch Bleeding???

Technical advice Q&A
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cdaubs
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#1 Clutch Bleeding???

Post by cdaubs » Sun Oct 30, 2016 12:44 am

OK, I need some help here. After pulling and rebuilding engine I also replaced the clutch slave cylinder. See the pic below. I believe it is the "short" one.

Image

So now the engine is back in and most things are hooked up. I'm trying to bleed the clutch system and I just can't seem to get the fluid to flow through the lines. The reservoir is full of fluid. All of the clutch lines are connected and not leaking. I have tried pumping the clutch pedal and it is soft all of the way to the floor, no pressure at all. I have left the bleed nipple open to try to gravity bleed the lines and no luck. I have also tried a vacuum type bleeder (Mityvac) with no success.

What am I doing wrong? :cussing: :banghead:

Please help!

:thankyouyellow:
Charlie Daubs
'64 FHC #890093

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bitsobrits
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#2 Re: Clutch Bleeding???

Post by bitsobrits » Sun Oct 30, 2016 1:18 am

Charlie,

You've checked the pushrod length so it has the just a bit of free play, yes?

Sounds like you may have an issue with your master cylinder. I always dissemble and clean even new cylinders to eliminate issues caused by parts sitting too long on the shelf.
Steve
'65 S1 4.2 FHC (early)

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abowie
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#3 Re: Clutch Bleeding???

Post by abowie » Sun Oct 30, 2016 3:57 am

http://www.projectetype.com/index.php/t ... ringe.html

The Gunson Ezibleed also works well.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1979 MGB (supercharged).
Adelaide, Australia

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MarekH
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#4 Re: Clutch Bleeding???

Post by MarekH » Sun Oct 30, 2016 8:37 am

Gravity bleeding works because the default position for the clutch master cylinder is that it open to the reservoir and clutch line. Upon first depressing the pedal, any free play at the top is taken up and the open gap between the clutch line and the reservoir is closed shut by a small rubber washer on the end of the master's pushrod. Further depressing the master pushrod into the cylinder now pumps liquid from inside the body of the master down the clutch line and into the slave, which moves accordingly. (The reservoir is disconnected from the circuit remember.)

You can isolate where your problem is by disconnecting the various joints and seeing what comes out where.

I'd bleed it with meths first until it works and then put clutch fluid in.

kind regards
Marek

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PeterCrespin
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#5 Re: Clutch Bleeding???

Post by PeterCrespin » Sun Oct 30, 2016 9:02 am

The symptoms fit with a failure to prime the M/C due to the typical air lock in the loop of the reservoir supply pipe. A pressure or vacuum bleed should hurry things along, but occasionally the section with air is so long that you never get fluid over the 'weir' as it were.

Bench-priming macter cylinders is normally effective, but once installed it's not worth removing them to do it. I once used a long section of temporary clear hose on a LHD car and suspended the reservoir a foot or two above the clutch master to watch the huge bubble travel upwards, before emerging into the reservoir. This then topped up the line and allowed normal bleeding to pump remaining air out.
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 2001 Vanden Plas

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Durango2k
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#6 Re: Clutch Bleeding???

Post by Durango2k » Sun Oct 30, 2016 9:46 am

I used a vac suction tool. Connected to nipple under car, long hose (because LHD), then let it suck (its a hand pump, gun style) until I had clear silicone fluid (in fact it was foamy).

Then, put long hose into reservoir, and used left foot to pump more in circle.

Finally, when no bubbles came, went down under and torqued nipple up.

Will have to repeat, because still a bit spongy, but that sounds normal- the silicone takes some time to get all the micro-bubbles out, and so I let it stand for a week now.

Carsten
Jag E '66 S1 2+2, 74’Citroen DS 23 Pallas iE, 73’ Citroen SM 3.0, 54’ Citroen 11 BL, 71‘ Velosolex, 88‘ Unimog U1650

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