A general clutch question

mcbutler · Post by **mcbutler** » Mon Sep 20, 2021 9:15 am

Hi all,

Right this is not specifically zed related but we have a lot of knowledge on here and I cant get good advice anywhere else.

I have a large transit with hydraulic clutch, just a master cylinder - steel pipe - slave cylinder.

It leaks absolutely no fluid whatsoever but I am getting air in the system, broken down three times in three weeks.
AA guy said change master cylinder, brand new ford item fitted, pedal was great, last night (5 days later) it goes again, no fluid lost and no leaks..

Any ideas fellas??/

Chippie · Post by **Chippie** » Mon Sep 20, 2021 1:57 pm

I can only think there is either a loose/leaking (not air tight) joint or a bit of corrosion that’s letting the air in. Probably not easy to find

Conrod · Post by **Conrod** » Mon Sep 20, 2021 2:06 pm

If no fluid is being lost, then the most likely cause is a worn piston seal which is allowing the fluid to seep past it. Having already replaced the master cylinder, the slave cylinder would be the next suspect. Although thinking about it, if fluid is seeping past the slave piston seal, then I would have thought you'd see a leak.

Smartbear · Post by **Smartbear** » Mon Sep 20, 2021 2:06 pm

With a new master cylinder fitted I’d be looking at the slave cylinder, there’s not really much else it could be.
Rob

Rockhopper · Post by **Rockhopper** » Mon Sep 20, 2021 3:56 pm

Is it a concentric slave cylinder? If its leaking onto the bell housing you won't see the fluid.

mcbutler · Post by **mcbutler** » Mon Sep 20, 2021 5:40 pm

Rockhopper wrote: ↑Mon Sep 20, 2021 3:56 pm Is it a concentric slave cylinder? If its leaking onto the bell housing you won't see the fluid.

It is concentric, the bell housing has a weep hole to reveal fluid loss, but as stated I am not losing any fluid at all!!!

Got me baffled

enuff_zed · Post by **enuff_zed** » Mon Sep 20, 2021 6:02 pm

If you have an internal failure in the cylinder then the fluid could simply be moving past the seal from one side to the other, without leaking out anywhere.

Rockhopper · Post by **Rockhopper** » Mon Sep 20, 2021 6:15 pm

It only needs to loose a tiny bit - it’ll be spread all over the inside of the bell housing.

mcbutler · Post by **mcbutler** » Mon Sep 20, 2021 9:07 pm

enuff_zed wrote: ↑Mon Sep 20, 2021 6:02 pm If you have an internal failure in the cylinder then the fluid could simply be moving past the seal from one side to the other, without leaking out anywhere.

Thats an interesting theory bud, thanks for that.

mcbutler · Post by **mcbutler** » Mon Sep 20, 2021 9:09 pm

Rockhopper wrote: ↑Mon Sep 20, 2021 6:15 pm It only needs to loose a tiny bit - it’ll be spread all over the inside of the bell housing.

The transit clutch shares the brake master reservoir the amount of fluid you would need to lose for the feed to the clutch master cylinder to be exposed would be around a mug full which would be obvious i think. Still I am not losing any fluid at all, no topping up needed.....

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