Hi All,

I have had a slow leak on my clutch slave cylinder for some time now. I have acquired a second hand slave cylinder. I am cleaning it up, and I’m about to soak it in clean brake fluid over night, ready to fit tomorrow.

Will it be OK to soak the rubber boot too, or should it be removed first

Also, I’m wondering if DOT5 brake and clutch fluid will be better than the recommended DOT3

Funny there is no recommended service interval for replacing all the clutch fluid. I guess I may as well; surely it degrades over time. I presume this will extend the life of the Clutch Master Cylinder, or could I be opening another can of worms?





As you can see I was successful with the 7MM Bleed screw

Regards All,

Re: Hydraulic Clutch Questions.

The hydraulic fluid is "shared" with the brakes?

In which case, yes, very good idea to flush and renew anyway

Re: Hydraulic Clutch Questions.

Nah the fluid isn’t shared . There are separate reservoirs for clutch and brake systems.

Brake and clutch fluid is the same stuff LOL.

Re: Hydraulic Clutch Questions.

Louie,

I was wondering the same thing when I saw blue clutch fluid in my X1/9 - original FIAT DOT3 fluid is blue, so maybe it's the original

Realistically, the difference between DOT5 and earlier types is going to be the boiling point - hardly relevant to the clutch, I think you'll agree! - and the DOT5.1 is silicone I think? You can tell because of the big price difference! There's always been a big debate about silicone (risks of damage to rubber seals, 'compressibility') and I don't think it's worth using - you might just as well change the brake fluid every two years instead, something will need doing by then!

But what about the clutch fluid - well, maybe moisture does get into the fluid over time. There's no risk of it boiling, but it could be leading to corrosion - such as what you are fixing, perhaps? You are going to end up changing it, I think, as you bleed the system.

I haven't heard of soaking the cylinder in brake fluid before fitting, although the fluid won't affect the rubber boot. I would probably have taken it apart and greased the seals with rubber grease - also check that the bore hasn't rusted during storage? Anyway, it would probably be fine if you just bolted it on.

Good to see you got that bleed nipple out - obviously it has suffered from some salt spray! Might be a good idea to fit a new one, rather than risk it seizing in the future. Depends how long you'll keep the car!

Bleeding the clutch - I've never done this, but you will have to I suspect that if you just opened the bleed nipple and pumped the pedal a few times until fluid appeared, and then attached a long clear tube, you could rig up the tube so that the end is higher than the master cylinder, and then just watch the bubbles work their way up?

Air should always find its way to the highest point in the system - so when I bleed my brakes, I just attach a tube with the end lifted above the level of the master cylinder. Keep putting fluid in at the reservoir, and you should see the bubbles work their way through the bleed tube, up and out - without getting sucked back in. I think it's important not to slacken the bleed nipple too far, in case air gets in around the threads.

I do the bleeding single-handed in this way. I use DOT4 brake fluid - it is cheap compared with the risks of ineffective brakes - so I'm careful to pump through plenty of fluid to convince myself that it's changed and air bled out. Brake fluid is also water-soluble, so I think it dissolves harmlessly if poured in the garden. I hope!

Please let us know how the fitting/bleeding goes...

Thanks,
-Alex

Re: Hydraulic Clutch Questions.

description Alex!

Last night I found I had no brake fluid left so no soaking :bang: .

I will try the up hill bleeding technique – Pet shop is next door to motor factors – so a couple of meters of fish tank air line added to my list.

I will look into the Rubber grease, but the boot looks happy fitted to the cylinder – I reckon if I try and remove it, I will end up damaging it

Nice 1 Alex!

Hydraulic Clutch Sorted.

All this dirt from 1 cylinder?

I decided to bleed all the mess through before changing the cylinder.

Alex the up hill thing works fine (Rep awarded )

LOL I wonder if FIAT fitted black fluid as standard – I reckon this is the original stuff.

How dirty?

I found the slave cylinder fitted with half-inch bolts – not 13MM.

I believe the Bosch cylinder I fitted is an aftermarket version. This is the old one.

Regards All,

Hei.

If the hydraulic clutch fluid is the same as brake fluid, it will bind itself to any moist. Brake fluid is hygroscopic, and will attract water. This leads to poor braking power. This might happen to the clutch aswell. The later Unos in Norway were equipped with the c513 gearbox, and not the c514. c513 was cable driven, and not with hydraulics as the c514... So not a problem here. .

Morten.

Hi Morten,

The clutch feels nicer already. I have yet to bleed the Clutch Master Cylinder. I will keep you updated.

Hydraulic Clutch Master Cylinder.

Louie Bee said:

...I have yet to bleed the Clutch Master Cylinder.

Click to expand...

Wrong!

Today I found no bleed screw in the master clutch cylinder .

As it is only 1 line, all the fluid was changed Via old slave cylinder .

Re: Hydraulic Clutch Master Cylinder.

Nice work Louie,
Should encourage some others here to bleed the clutch hydraulics and hopefully the brakes too

I think it's normal for the master cylinder (in a hydraulic system) not to have a bleed screw. I like the method shown for holding down the clutch pedal. I use a jack handle with the seat brought forward. Did you find there was a continuous flow of fluid with the pedal held down?

I was a bit surprised to find when I got my Tipo DGT three years ago, it had a cable clutch. Seems that FIAT switched from cable to hydraulic, then back to cable again. The last of the Unos came with basically a 1372cc Tipo motor and gearbox, so it doesn't surprise me that they have a cable. Also, my Uno Turbo has a complicated cable setup with a couple of pulleys to 'bend' the cable 90 degrees and get it past the hot exhaust (LHD wouldn't have this problem!)

For the X1/9, a cable was impractical, so it has hydraulics. So far, I've left alone - but the fluid can't be in very good shape by now!

Glad the technique worked and thanks for the 'reputation' - but I can't help thinking that you should take points off when I make a mistake (like with the vacuum advance on an Uno 1.0 Start... it didn't have any)

-Alex

Hydraulic Clutch bleed

alexGS said:

Did you find there was a continuous flow of fluid with the pedal held down?

Click to expand...

Nah I opened bleed screw, a little came up – then nothing till a depression of peddle, then only as much as master cylinder holds, hence jam peddle down, close bleed screw, let peddle up and back to opening bleed screw. I found I could do 5 cycles between filling reservoir.

A Dutch friend suggested Jamming peddle down, then Opening + closing bled screw, letting the Clutch’s spring push the fluid out. I guess this method means half as many trips to the peddled

I thought the last Unos had a Punto style box – C514 or C513 for Sweden (lol Morten) – with / without a hydraulic clutch respectively.

A word of warning – if your going to bleed clutch, were gloves. my hands have red bumps all over the backs .

alexGS said:

Glad the technique worked and thanks for the 'reputation' - but I can't help thinking that you should take points off when I make a mistake (like with the vacuum advance on an Uno 1.0 Start... it didn't have any)

Click to expand...

https://www.fiatforum.com/showthread.php?p=321577 my 1.0 Start has a lovely vacuum advance.

Louie Bee said:

In the mean time, anyone know if the Vacuum advance should be oil filled?????

Click to expand...

Still wondering LOL. Maybe I should take points off you as I think you know the answer :tempt:

Hye all..
just read this thread with interest as my cylinder is goosed.IE pedal goes all the way to the floor,and after i filled the little pot up noticed it emptied the oil out near the cylinder..
so i am looking for details of stripping off and replacing please. pitfalls, idiot proof guide that kinda thing. cheers

1995 m diesel uno start...

Hi alfacool,

Welcome to the forum it was 6 months ago I did this job, so I’m doing it from memory.

Pleases tell us you didn’t put oil in that reservoir . I wouldn’t know how to clean out the whole system if you have. Assuming you used brake/clutch fluid ...

If you’re sure it’s the slave cylinder leaking (one on the gearbox) and not the pipe leading to it, get a new part. I’m not sure if the Diesel’s hydraulic clutch uses the same. If they are, http://www.shop4parts.co.uk sell cylinders for less than a fiat dealer. You could get one off a scrap yard, but how long will it last?



If it’s the same as mine, to remove the slave cylinder:-

Soak bolts 1 and 3 with penetrating fluid of WD40

Undo the two bolts holding it to the gearbox (number 1 on attached diagram).

Have a cloth ready to mop up spills, as clutch/brake fluid will ruin paint.

There is a bolt holding the rigid pipe onto the cylinder (at point 2 on diagram). Grip this with a spanner, and twist the cylinder till it’s free of the pipe. Mop up any fluid that flows out.

Fix the new slave cylinder to the pipe (again holding pipe still).

Introduce cylinder ‘tip’ (4) to clutch arm, align cylinder and bolt (1) back on to gearbox.




Bleed clutch.

Fit a fish tank airline (or similar) to the bleed nipple (4), feed the other end up hill to a jam jar.

Top up clutch reservoir with fresh unshaken Brake/clutch fluid and replace cap.

Unscrew the bleed nipple about 1 turn.
Press clutch and jam down (or have an assistant hold down).
Re tighten bleed nipple.
Un jam clutch peddle (or assistant to release).

Repeat above 4 steps, topping up reservoir after 4 reps, until you see clean bubble free fluid in the pipe. Be careful the pipe stays in place, and the jam jar doesn’t over fill.

End with a tight bleed nipple and reservoir topped to max line(with cap on). Kink the pipe and remove it. Mop up any spills.

Excellent guide there Louie!

Dot 3, 4 and 5.1 is glycol based fluid. Dot 5 is Silicone based.

As its a clutch and not brakes, you could use anything really. The boiling point is not going to matter. Silicone fluid may be a good idea as its not hygroscopic. You may get a slightly mushier pedal as its compressable but I doubt you will notice the difference.

Brake fluid flushes should be done every 1-2 years. Its easy to do the clutch at the same time.

Louie,

Great write-up!
I particularly liked the use of the word 'introduce' - as in 'offer up', then drop on ground, reposition again, convince yourself that it doesn't go the other way around, and then hold in position with a third hand... OK probably not for this particular job but I'm sure we've all been there.

I wonder if your employers know of your true documentation abilities.

Meanwhile it might be a good time to confirm that no, vacuum devices shouldn't be filled with oil - you can always count on me for a quick answer: only six months! - but it often happens if the vacuum pipe leads downwards from the inlet manifold. Clean out with 'brake cleaner' aerosol (carburettor cleaner can be a little too aggressive), although we also have really cheap engine degreaser aerosols available over here. This is pretty universal stuff - it makes grease and oil water-soluble. So, you spray all the bits with degreaser and then wash in soapy water. Finally dry with hot-air gun.

Now back on-topic - I always worry with clutches about the risk of getting air back into the system - so I think that getting a long piece of suspended plastic pipe is still a good idea. Maybe that way I'll actually change the clutch fluid in my 1988 X1/9, which (being blue) is probably still the original...

Thanks!
-Alex

Thank you very much for a quick responce,
i can get a new cylinder for 23 quid from my local motor factors and with your guide its time to wd40 my nuts (and bolts) and get the old girl back to life...

Nice one Alex – thanks for the rapid response . I think I’ll leave the diaphragm as it is for now. I pumped most of the oil out back then and its been OK since.

Alex I’d get your clutch fluid changed – as SteveNZ says – every 2 years, not 20

Good Luck with the switch alfacool – I’ve added the WD40 bit in above. I knew there was something I forgot . let us know how you get on

Any way guys, thanks for the compliments.

mmmm!!!!
I have just had a good look at me cylinder job to do and i have a bracket/cover above the cylinder that you dont talk about in your knob on guide, i have tried to loosen said cover and as expected is well tight :bang: one bolt sits vertical which i can get, one nut and bolt is on the gearbox and only able to get from under the car,and the last is kinda down below the battery box and also bolted to the gearbox and it doesnt look like you can get a spanner as there is a cast lump on the box in the way so will cover the nuts in wd get me breaking bar out do the vertical and the one under and maybe bend the bracket up then i can begin the job i wanted to do in the first place.who said working on uno,s was easy.or is it cos its an oil burner and everything is beefed up so it doesnt shake itself to bits

alfacool said:

mmmm!!!!
I have just had a good look at me cylinder job to do and i have a bracket/cover above the cylinder that you dont talk about in your knob on guide, i have tried to loosen said cover and as expected is well tight :bang: one bolt sits vertical which i can get, one nut and bolt is on the gearbox and only able to get from under the car,and the last is kinda down below the battery box and also bolted to the gearbox and it doesnt look like you can get a spanner as there is a cast lump on the box in the way so will cover the nuts in wd get me breaking bar out do the vertical and the one under and maybe bend the bracket up then i can begin the job i wanted to do in the first place.who said working on uno,s was easy.or is it cos its an oil burner and everything is beefed up so it doesnt shake itself to bits

Click to expand...

sometimes the slave clutch cylinder is held on by a circlip.check this out.its not very easy to see but not sure on the uno.tipo one is circliped.