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Strange Clutch Issue, Master Cylinder?


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#1 joeaustin

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Posted 12 November 2013 - 02:21 AM

hi all, my 88 mini has a very strange intermittent (verto) clutch issue, when getting in the car the clutch goes straight down and has no pressure at all, but then if i pump the clutch pedal a few times it gets firmer until eventually it works.

 

bit of a problem though when driving as it seems to fairly quickly become ineffective, as in I could be driving down the road away from the lights and it'd be fine, but then by the time I get to another set of lights i'll need to pump the clutch several times again until it works just to get back in gear.

 

could this be the master cylinder needing replacement? is it a leak?

 

thanks in advance for any help :)



#2 usurp66

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Posted 12 November 2013 - 06:44 AM

Best to have someone operate the clutch and see if the slave cylinder is moving the clutch arm and by how much. It could simply be air in the system that needs to be bled or a faulty slave or master cylinder but if the problem persists I would start by bleeding the system first.

Hope that helps?



#3 joeaustin

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Posted 12 November 2013 - 12:36 PM

Best to have someone operate the clutch and see if the slave cylinder is moving the clutch arm and by how much. It could simply be air in the system that needs to be bled or a faulty slave or master cylinder but if the problem persists I would start by bleeding the system first.

Hope that helps?

 

another person operating the clutch was how i noticed, he just happened to press the clutch down a few times while i was watching and i noticed it started moving further each time until it was useable again.

 

i bled the system initially about a month ago then pretty much every week since as that was my first thought, must be a leak if i have to top up the master cylinder then right?

 

I'll buy a repair kit for the master and slave just in case, read on another forum that if one of the seals is worn then the other probably will be as well. is it a big job to take on and are there any bits i might need like pins etc?



#4 usurp66

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Posted 12 November 2013 - 12:48 PM

 

Best to have someone operate the clutch and see if the slave cylinder is moving the clutch arm and by how much. It could simply be air in the system that needs to be bled or a faulty slave or master cylinder but if the problem persists I would start by bleeding the system first.

Hope that helps?

 

another person operating the clutch was how i noticed, he just happened to press the clutch down a few times while i was watching and i noticed it started moving further each time until it was useable again.

 

i bled the system initially about a month ago then pretty much every week since as that was my first thought, must be a leak if i have to top up the master cylinder then right?

 

I'll buy a repair kit for the master and slave just in case, read on another forum that if one of the seals is worn then the other probably will be as well. is it a big job to take on and are there any bits i might need like pins etc?

 

I think I would try the slave cylinder first as it should be pretty striaghtforward and is probably the one to fail first as it is more exposed to the elements. I have never done a master cylinder so i can't really comment.

You might also check that you do not have a hairline crack in the clutch line somewhere. If you are careful and carefully dry around all the hydraulic components you should be able to spot any leaks while your friend operates the clutch for you.



#5 baldric

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Posted 12 November 2013 - 02:22 PM

sounds very much like air in the system ... check the flexible hose from bulk head to slave cylinder this can give problem when it gets a bit old check the master cylinder inside the footwell for fluid loss ,,, the way you explain your symptoms sounds like you have a lot of air in the line bleeding the system is a slow job by that I mean it has to be done slow so that you do not introduce more air into the system pedal down slowly crack bleed screw pedal up slowly 2 handed operation one other thing check the return spring from the clutch lever to slave cylinder make sure the push rod fully returns back in the cylinder by pushing back the clutch lever arm make sure all your clutch adjustments set right follow the manual ,,, how it is done ,,, check my scribes on the technical that might give you some idea of how things work gives exploded view of master and slave cylinder I pieces there is a few things that need to be addressed before a clutch system works perfect

#6 joeaustin

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Posted 15 November 2013 - 03:11 PM

update: followed the manual and everyone's advice on here and tried bleeding it properly, result was going through about half a litre of fluid and still no improvement, i've ran out of fluid now so stopped.

i was watching the tube from the bleed nipple while my mate operated the clutch and there seemed to be no improvement in the amount of bubbles coming out with the fluid, i'm thinking there must be some air getting in somewhere, maybe cracked somewhere? can't see any leaks anywhere though other than when i accidentally filled the master cylinder to the brim of the neck and a small amount came out of the lid. is this meant to happen or is that the source of the problem? there's a hole in the lid that looks like it's meant to be there so i'm guessing it's just in case you overfill it like i've just done

 

i'm considering replacing the entire hydraulic system because it looks so old and replacing all the pipework with new flexible hose but ideally i need it to be usable by tomorrow to go to work...

I have a master cylinder and slave cylinder repair kit but no brake fluid left and I don't really want to start fixing it now as I park on the street (no garage) and it gets dark early so would be a pain to see what i'm doing.

 

any suggestions/anyone in the manchester area who happens to have replacement bits and would be willing to help fix them tonight/early tomorrow?



#7 joeaustin

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Posted 17 November 2013 - 08:19 AM

Further update: rang a local mini specialist and on his advice bled the clutch by having the pedal pressed down, opening the bleed nipple, closing it, pedal up and repeat till only fluid came out. (The way I did it originally)This worked fine for a while but the next day was completely useless and possibly worse than before so I must have a leak or master cylinder problems, going to take my poorly mini to the guy I rang to have a look at unless anyone has any ideas?
Had to drive it this morning about 9 miles without the clutch so I assume I'll have done some damage somewhere gearboxy which will probably break just about when the clutch is fixed.... yayyyyyy

#8 ejs-1995

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Posted 17 November 2013 - 09:17 AM

Nahh the gearbox should be ok, my old man was drove my car with no clutch for a good couple of miles and the only thing that suffered was the battery were you crank it in gear.(it was a tired battery anyway!)

#9 g-dog

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Posted 17 November 2013 - 09:49 AM

If you've added fluid and the level keeps dropping without leaks Its got to be the master cylinder. A seal is going or gone and the whole thing is filling up with fluid. G

#10 joeaustin

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Posted 19 November 2013 - 11:34 PM

yeah i rang a lovely bloke at north west mini centre who said that it must be either the seals or the master cylinder so he's going to come pick it up tomorrow and sort it for me (i'd like to do it myself but i'm really busy at the moment and i need to use it asap really...)

 

i'm thinking if the master cylinder does need replacing i might as well replace all of the hydraulic system so it's all shiny and new, maybe with all flexible hose like the ones you can get on minispares as the standard pipe looks a bit crap to be honest like.

 

i'll update again when it's fixed with what the problem was, cheers for everyone's help :)



#11 joeaustin

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Posted 21 November 2013 - 09:12 PM

Guy from nwmc came yesterday and dropped it back off today (was a horrible moment watching my car being trailered away, don't think i'll ever be able to sell it)

Turns out the problem was the slave cylinder needed to be replaced, so that's done now, problem solved, i just have to get used to the biting point being really high up again now...

 

asked him to tune the carb as well and it just feels different now, the timing was 7 degrees out and the distributor vacuum apparantly does nothing at all...

i was running it fairly rich before and it feels slower now... maybe it's just me...

 

anyway it's all sorted and works but obviously another problem has been found in that the heater matrix is leaking a little bit, so does that entire unit need replacing or could it just be the pipework going into it?

 

also he said the cylinder bearing is whining so that'll need looking at soon, not entirely sure what this will involve so that'll be another adventure wooooo

thanks again for everyone's help and advice on this






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