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Problems Bleeding Clutch (Air In Line)


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#1 Zeemax_Mini

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Posted 12 October 2019 - 10:57 AM

Hey guys,

I'm trying to bleed the clutch in my pre verto mini but it keeps getting air in it just when I think it's clearing. Everything is new Inc slave and master but I can only think it's sucking air in somewhere as we've bled it for hours. We've made sure all the joints are tight so unsure what to check next...ang ideas? At the moment my best guess is a duff new slave or master but before I strip them down I thought I'd ask.

Cheers, Dom

#2 Zeemax_Mini

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Posted 13 October 2019 - 01:53 PM

Bump!

#3 panky

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Posted 13 October 2019 - 02:11 PM

What I do is to fit a piece of tightly fitting plastic tube onto the bleed nipple with the other end in a container with some brake fluid in covering the end of the tube. Then crack the bleed nipple only slightly and pump the pedal a few times, you will hear the fluid and air squishing through. top up the fluid level and repeat a couple of times then nip up the nipple and see what happens, you can smear a bit of red rubber grease around the nipple threads to stop air getting in if needed. It's always worked for me in the past. It's better if you have someone watching the fluid level as you pump the pedal but I've done it by myself. 



#4 Zeemax_Mini

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Posted 13 October 2019 - 04:40 PM

Cheers mate, bar the rubber grease that's exactly what I've been doing with my dad. It seems to totally clear after a few pumps, but then the next one it suddenly has a load of air in it. Very strange!

#5 panky

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Posted 13 October 2019 - 08:28 PM

Did you leave the nipple open and just pump away?



#6 Avtovaz

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Posted 13 October 2019 - 08:47 PM

i had a absolute mare doing the one on the mini van. I had to push the slave right in and reverse bleed it.



#7 MiniMadRacer

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Posted 14 October 2019 - 10:34 AM

Did you replace the rubber hose ?



#8 Chris1275gt

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Posted 14 October 2019 - 11:21 AM

I had a mare so undid the slave cylinder from the clutch housing and held it vertically so the bleed nipple was at the top two pumps on the pedal and the air flew out and all done.

#9 Zeemax_Mini

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Posted 16 October 2019 - 06:16 PM

Hey all, apologies for the lack of reply - busy week and totally forgot I'd posted. Thanks for all the tips, I'll give them a go. My gut is that there's a leak somewhere but I just can't find one, but the amount of air we've got out of it just can't be right (we've gone through two bottles of dot 5). No weeping nipples or unions we can see, or fluid in the slave. Will try holding the slave vertically.

Cheers!

Dom

#10 Zeemax_Mini

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Posted 16 October 2019 - 06:16 PM

Did you replace the rubber hose ?


Yep it's a new braided hose.

Dom

#11 Dusky

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Posted 17 October 2019 - 05:30 AM

I had the same problem once, had to replace the metal pipe between the master and flexi. Somehow it couldn't seal properly anymore after all those years.

#12 Pigeonto

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Posted 17 October 2019 - 10:11 AM

I'd be trying another slave cylinder. I know you said it's new.

Assuming you're closing the bleed nipple for the return upward stroke of the pedal ?

The idea of that is to force the master to take in a new charge of fluid from the reservoir. 

However it requires  the cup seal in the slave to seal in the reverse direction when doing so and if the seal is a little weak or chinese it may not, so in goes the air



#13 Ethel

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Posted 17 October 2019 - 12:38 PM

Get gravity on your side by unbolting it and tilting so the nipple is highest.

 

You could also try holding the pedal down to isolate the reservoir, then open the bleed screw and push the piston in to the slave cylinder to expel its contents (including trapped air). Close the bleed screw before releasing the pedal and the slave will refill itself by drawing fluid through from the reservoir.



#14 CityEPete

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Posted 18 October 2019 - 10:42 AM

I use a perfectly clean glass jar to collect the fluid and dip the end of the tube into, all that dot 5 could have been saved!




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