Technical Stilo 2.4 clutch master cylinder mystery & dilemma

[jonti]

The mystery is why my Stilo got through five or so clutch master cylinders in 13 years or so and 40k miles.
I see lots of threads about floppy pedals and master cylinders, but it's not clear if there are more issues than there should be or I am alone in this.
So here we go again. Reverse is not available when the car is hot, and recently I've depended on the goodwill of strangers willing to push when I've forgot and gone into a cul-de-sac.

 

[jonti]

I am thinking that the cheapo black plastic body expands with heat over time and no longer seals. More recently, a metal bodied MC from TRW or Bosch has become available, which MIGHT support my theory. As why would they change to metal, unless it resolved a problem with the OEM design?

So I bought a metal one for a rainy day and that day has come. But on removing the old one, the new metal MC plunger is too long and won't fit. Looking back at the listing, it states 'LHD'. A few others for sale state this and generally they ALL look this long, apart from Shop for Parts which (for the 2.4) is the correct length, but it's the usual plastic one. Mystery (2) then, is it just the 2.4 MC that is short, or is it shorter on all RHD's? I assume just the 2.4, as there will be a lot of surplus stock. Or are sellers using incorrect library pictures, maybe another mystery.

My dilemma is whether to try putting the short plunger from the plastic one into the metal body. I've removed them both. It seems to be a nice tight fit. But I can't be certain my theory about the case expanding is correct? Maybe it is the seals as they age, although the seals from my old plastic one 'look' ok.........

 

[Maxcaddy]

Bit unclear from the photos, but by saying Plunger you mean the piston and not the operating rod ?, If it is the piston then the cylinder will most likely be different, and probably the orifices will be in different positions, and it wont work. You don't say exactly why you can't fit the later one in its entirety, but if it's fouling against something, can you move whatever that something is ?

If it is the operating rod then as long as the end which contacts the piston is the same, I see no reason why swapping them would be an issue.

If needs be you could fairly easily put together a test rig, and then see what was actually happening when assembled.

 

[Davren]

So I bought a metal one for a rainy day and that day has come. But on removing the old one, the new metal MC plunger is too long and won't fit. Looking back at the listing, it states 'LHD'. A few others for sale state this and generally they ALL look this long, apart from Shop for Parts which (for the 2.4) is the correct length, but it's the usual plastic one. Mystery (2) then, is it just the 2.4 MC that is short, or is it shorter on all RHD's?

For all Stilos, the LHD (Left Hand Drive) clutch cylinder rod is longer that the RHD version. It's because of the location of the clutch pedal, and therefore the cylinder, within the car.
.

 

[jonti]

Bit unclear from the photos, but by saying Plunger you mean the piston and not the operating rod ?, If it is the piston then the cylinder will most likely be different, and probably the orifices will be in different positions, and it wont work. You don't say exactly why you can't fit the later one in its entirety, but if it's fouling against something, can you move whatever that something is ?

If it is the operating rod then as long as the end which contacts the piston is the same, I see no reason why swapping them would be an issue.

If needs be you could fairly easily put together a test rig, and then see what was actually happening when assembled.

the operating rod of the metal bodied replacement MC is longer than the Valeo OEM type MC. So the new one won't work at all, as the rod needs to be the correct (valeo) length to fit between the bulkhead and the pedal. your suggestion of a test is a good one, as I steamed ahead without testing the metal body/valeo rod combo. When the pressure bleeder quickly lost pressure, i realised the contents of the brake fluid resevoir were now in the driver's footwell :-o

 

[jonti]

For all Stilos, the LHD (Left Hand Drive) clutch cylinder rod is longer that the RHD version. It's because of the location of the clutch pedal, and therefore the cylinder, within the car.
.

Thanks for this. So much of the non-Valeo stock for sale appears not for the UK Stilo, as they show the LHD (longer) version.

 

[aschiuta]

the operating rod of the metal bodied replacement MC is longer than the Valeo OEM type MC. So the new one won't work at all, as the rod needs to be the correct (valeo) length to fit between the bulkhead and the pedal. your suggestion of a test is a good one, as I steamed ahead without testing the metal body/valeo rod combo. When the pressure bleeder quickly lost pressure, i realised the contents of the brake fluid resevoir were now in the driver's footwell :-o

Why you dont cut it to the right length for RHD version?

 

[jonti]

Why you dont cut it to the right length for RHD version?

This will be the only way, other than buying the Valeo version. This can only work by cutting a section out and rejoining them, as you need the bobble at the end of the rod that fits into the pedal.

 

[jonti]

I ordered another Stilo master clutch cylinder and this was turned up. From Davren's info. above, it looks to me as stock is now LHD master cylinders which are too big for UK cars. I cut the length down by 9.5cm. Initial signs were good with a firm pedal, but no reverse. Then the pedal went flat, so I'll try again tomorrow. Dry in the footwell though, so no Rug Doctor machine this time, although the hall carpet got a clean as well as the Stilo......

 

[Maxcaddy]

Doesn't look that there's any logical reason why it won't work. Not sure why one push rod couldn't be swapped over for the other, but you've done a tidy fix, so fingers crossed .

 

[jonti]

Doesn't look that there's any logical reason why it won't work. Not sure why one push rod couldn't be swapped over for the other, but you've done a tidy fix, so fingers crossed .

The rod in the plastic Valeo one (which is UK size) is retained using a plastic clip. The metal bodied cylinder (not UK size, too long, but metal may cure my issue) retains the rod with a snap ring. I tried to combine them, but the fluid leaked out the end. Had I not reused the snap ring, perhaps it might have worked, but they are slightly different in detail, including the integral piston.

 

[jonti]

The rod in the plastic Valeo one (which is UK size) is retained using a plastic clip. The metal bodied cylinder (not UK size, too long, but metal may cure my issue) retains the rod with a snap ring. I tried to combine them, but the fluid leaked out the end. Had I not reused the snap ring, perhaps it might have worked, but they are slightly different in detail, including the integral piston.

The current conclusion to this is that it is still a mystery. The 'continental' metal-bodied master cylinder appears to be working fine with the rod shortened to UK spec. Inability to select reverse and 5th gear didn't improve however. Some forum posts referred to linkage corrosion, so knocked out the little metal axle in the linkage that sticks and stops revolving, greased it copiously with cv-type lithium grease and it was quite a bit better. This lasted a month but I'm half back to where I was initially with gears unavailable when hot. I wouldn't imagine the metal axle would expand with engine heat so that it can't turn? Or the grease would burn off?

 

[Moreno83]

The current conclusion to this is that it is still a mystery. The 'continental' metal-bodied master cylinder appears to be working fine with the rod shortened to UK spec. Inability to select reverse and 5th gear didn't improve however. Some forum posts referred to linkage corrosion, so knocked out the little metal axle in the linkage that sticks and stops revolving, greased it copiously with cv-type lithium grease and it was quite a bit better. This lasted a month but I'm half back to where I was initially with gears unavailable when hot. I wouldn't imagine the metal axle would expand with engine heat so that it can't turn? Or the grease would burn off?

I also have a Schumacher and i still have the plastic version on top of the gearbox. Basically just works on brake fluid/pressure. ( Which you know ).
The only thing i replaced when i restored it was the clutch bearing and i bled the system.

Since it is only when it is hot i would think there is still some air inside the system. You have ( out of my head ) 2 metal clips on your slave cylinder that is mounted on the gearbox. Maybe air is slowly getting in when you are pressing the clutch pedal?
Anyways my point is...the plastic version which is the original version is working fine.

Hope you will find a solution for your problem.

 

[Maxcaddy]

So your new (modified) Master cylinder is working fine, and hopefully will continue to do so, great news . However, you're still getting problems engaging 5th and reverse.

Two thoughts are that one, with the trouble you've had with the Master cylinder, are you sure that the Slave cylinder and release bearing are functioning correctly with the slave giving full travel, and the release bearing not worn down and needing more movement ? Although as its a concentric unit on the first motion shaft, I'm unsure how you could check that out without stripping out the gearbox .

The other thought is that it is a gear selector mechanism problem, similarly my 2003 1.8 needed 2 new selector 'plates' (or whatever Fiat call the casting that sits on top of the gearbox and has the gearchange cables go to it to move the selectors underneath) because the gears got so difficult to engage. When it happened the 2nd time (over 7 years of ownership) I kept that plate with a view that if it happened a 3rd time that I would use the 'seized' plate by cleaning it out and fitting a couple of grease nipples to ensure lubrication. Of course that car went to the scrappy and the 2004 Abarth that I replaced it with of course had a different plate arrangement entirely (maybe a few other folk had the same issue with early Stilos ?). Not sure what you have on yours but if it's the early one, then that is where I would start.

 

[Moreno83]

Two thoughts are that one, with the trouble you've had with the Master cylinder, are you sure that the Slave cylinder and release bearing are functioning correctly with the slave giving full travel, and the release bearing not worn down and needing more movement ?

I also think that it is not fully engaging and releasing the clutch to shift into gears. But since it is only when "its hot" i think there still is air inside the system. Maybe old brake fluid? Old brake fluid attracts moisture over time.
So personally i would not seek it into the mechanical side but in the air/brake fluid.....

 

[jonti]

I also think that it is not fully engaging and releasing the clutch to shift into gears. But since it is only when "its hot" i think there still is air inside the system. Maybe old brake fluid? Old brake fluid attracts moisture over time.
So personally i would not seek it into the mechanical side but in the air/brake fluid.....

I would usually suspect that. Back in the day when the car was serviced by Fiat, they replaced the master cylinder maybe twice in 5 years, when I encountered problems. Each time it solved it, although I suppose it could just have been the bleeding ! However the guy on the desk at the time said they'd done 'hundreds' (of master cylinders on Stilos) I questioned this later, as mine was likely the only Stilo they'd ever seen. They said he must have been referring to the previous place he worked. Like I said, all very mysterious really, but I took it from all this that the plastic cylinder was a bit carp. Now, replacing the MC and bleeding hasn't solved my problem, but fiddling with the linkage has liberated reverse and 5th most of the time although it's far from good.

 

[jonti]

The other thought is that it is a gear selector mechanism problem, similarly my 2003 1.8 needed 2 new selector 'plates' (or whatever Fiat call the casting that sits on top of the gearbox and has the gearchange cables go to it to move the selectors underneath) because the gears got so difficult to engage. When it happened the 2nd time (over 7 years of ownership) I kept that plate with a view that if it happened a 3rd time that I would use the 'seized' plate by cleaning it out and fitting a couple of grease nipples to ensure lubrication. Of course that car went to the scrappy and the 2004 Abarth that I replaced it with of course had a different plate arrangement entirely (maybe a few other folk had the same issue with early Stilos ?). Not sure what you have on yours but if it's the early one, then that is where I would start.

So I have this (the rubber boot faces upward) which sits on/in the box. Drifting out the linkage rod visible at the front and greasing it restored reverse and fifth, albeit it has stiffened up since. Strangely I didn't seem to have the rubber seal pictured at all. Was this the linkage you had on your earlier car, or was it a different set up?

 

[Maxcaddy]

What you have is (I think) the later style which is what I have on my Abarth (although I'm not near it to check). The earlier change had 2 pivoting arms which corroded within the aluminium casting. Unfortunately as yours is later, I have no further knowledge of potential failure mechanisms in the later change arrangement, and hence what your problem is caused by.

However if it happened to mine, or when it happens to mine (assuming mine is the same) I would strip the change down to ensure that A, that the cables were freely moving, and B, that the gear selection in the gearbox was smooth. If both of those were fine then its the change mechanism that is at fault, and a strip, clean and grease should cure all. Dependant on the design, the addition of a grease nipple or two will help immensely and stop or at least slow down future seizures.

 

[Maxcaddy]

It's amazing what you can find when you think you've lost it , here's the gearchange from my 03 1.8 (the early type)

 

[jonti]

It's amazing what you can find when you think you've lost it , here's the gearchange from my 03 1.8 (the early type

Well done - and so that older design part sells for over £60 at Alfa work shop (labelled for Alfa 156) Looks like it does the same function and so too the type of degradation that may affect operation. I'll see if can get a new unit from Fiat, copper ease it/dynax it and fit in Spring, as a day dismantling for access may help next time. It won't be cheap, but none for sale which may mean Fiat still hold the stock. At risk off going off topic can I ask for your experience of oil consumption? At £50k we suddenly have an appetite for oil, which we didn't before. The Selenia Racing seems quite thin for normal operating temps - 10w60?