1.4 TSI Slave / Master cylinder issues

Lewwy

L6 WWY
Feb 5, 2012
51
0
Bedworth, Warks
Yesterday when doing a 50 mile journey noticed the clutch pedal was feeling slightly strange on some of the gear changes, i.e. slower to return to normal position.
On my return journey I had the pedal hitting the floor and I had to pull it back up with my foot. Sometimes it was operating ok and other times I had to pull it back up. Managed to get home after being stuck in a lot of stop start traffic through Towcester. The last 5+ miles of the journey clutch was as normal. From stuff I have read I am assuming this is an issue with one of the clutch cylinders. The car is 1.4 TSI, 63 plate, just done 33k miles.

I have read things saying all MK3 Leon slave cylinders are concentric and inside the gearbox, so a gearbox off job to replace. However when I have looked this part up for mine it doesn't appear to be a concentric type and when looking in the engine bay I am pretty sure I can see it bolted to the outside of the bell housing (no fluid leaks around it at all and I've checked fluid level in reservoir and its not low). I am guessing this could mean a master cylinder problem?

Does anyone have any experience or advice on changing the slave or master cylinders on these? Is the slave cylinder as straight forward to change on the 1.4 TSI as it appears? i.e. 2 x bolts? If its the master cylinder can anyone suggest where to source this from?

Any help or advice greatly appreciated,
 

DigitalSushi

Active Member
Sep 7, 2020
145
66
This attached pd is what i can see in the service manuals i have for clutch cylinders, hope it can help
 

Attachments

  • clutchcylinders.pdf
    648.4 KB · Views: 298

Lewwy

L6 WWY
Feb 5, 2012
51
0
Bedworth, Warks
This attached pd is what i can see in the service manuals i have for clutch cylinders, hope it can help
Hi DigitalSushi thank you for the pdf information you have attached. This is very useful and interesting reading. Thanks for taking the time to find out this info.

I would be interested to know what the 'guided fault finding' entails that the dealers carry out prior to replacing either of the clutch cylinders. I haven't detected any fluid leaks on my car yet so not sure where to attack it first..... frustrating
 

DigitalSushi

Active Member
Sep 7, 2020
145
66
No problem, I can only assume that means plug the diagnostic computer in and follow the instructions.

these manuals i got I presume are the official jobs so they assume that you have all the seat toys like a dealership will have. Though i am thinking if you have a decent code reader then maybe that might highlight a fault code to you that may explain the problem.

I suppose the only way to check for leaks is find the pipes to the cylinders and work your way back
 
  • Like
Reactions: Lewwy

RUM4MO

Active Member
Jun 4, 2008
7,784
983
South Scotland
Have you been reading up on what actually can cause this, I'm only mentioning this as someone, maybe with a Skoda Octavia, came to the conclusion that this or some of this is caused by the removal of the internal spring that used to be inside the master cylinder, nowadays there is said to not be an internal spring, so the slave cylinder being acted by the returning force of the clutch cover diaphragm forces the slave cylinder back and that forces the master cylinder back, but with more of a pulse than the master cylinder's original design with an internal spring, and that can cause the seals to flip over enough to can cause the clutch pedal to get left behind on or near the floor. All that might sound like being pants, but some or all of it might be true and most of the time these newer systems do work, and sometimes they don't it seems. Just food for thought that is all.

Edit:- I'd think that the only codes or fault codes available for clutch operation will be the clutch pedal/cylinder switches, all the rest is simple hydraulics and then diaphragm.

Which means guided fault finding will be restricted to a few physical tests and visual checks - like any DIYer would carry out.
 
Last edited:
  • Like
Reactions: Lewwy

Lewwy

L6 WWY
Feb 5, 2012
51
0
Bedworth, Warks
No problem, I can only assume that means plug the diagnostic computer in and follow the instructions.

these manuals i got I presume are the official jobs so they assume that you have all the seat toys like a dealership will have. Though i am thinking if you have a decent code reader then maybe that might highlight a fault code to you that may explain the problem.

I suppose the only way to check for leaks is find the pipes to the cylinders and work your way back
Yes I can only assume too that there's some hook they do at the MD to assist them with this diagnostic. I have VCDS but didn't hold out much hope as I assume this is a purely mechanical fault. Although I am sure purely coincidental at the same time the clutch started being silly I have had a 'headlight level control' error flagged up. Totally new error that clears with a restart but flags up again after a short while. Strange. As you state I'm sure I will have to do my best to trace back through the pipework and see what I can see. Luckily in the 1.4 engine bay it's slightly more accessible than some of the bigger engine blocks. If there's no leaks anywhere I'm not sure. Don't necessarily want to start firing the parts cannon at it 😊
 

Lewwy

L6 WWY
Feb 5, 2012
51
0
Bedworth, Warks
Have you been reading up on what actually can cause this, I'm only mentioning this as someone, maybe with a Skoda Octavia, came to the conclusion that this or some of this is caused by the removal of the internal spring that used to be inside the master cylinder, nowadays there is said to not be an internal spring, so the slave cylinder being acted by the returning force of the clutch cover diaphragm forces the slave cylinder back and that forces the master cylinder back, but with more of a pulse than the master cylinder's original design with an internal spring, and that can cause the seals to flip over enough to can cause the clutch pedal to get left behind on or near the floor. All that might sound like being pants, but some or all of it might be true and most of the time these newer systems do work, and sometimes they don't it seems. Just food for thought that is all.

Edit:- I'd think that the only codes or fault codes available for clutch operation will be the clutch pedal/cylinder switches, all the rest is simple hydraulics and then diaphragm.

Which means guided fault finding will be restricted to a few physical tests and visual checks - like any DIYer would carry out.
RUN4MO thanks for your reply. I have been trying to read up on what causes this and have found varying information. The slave cylinder which appears to be external to the gearbox doesn't appear to have any leaks. I haven't investigated the master cylinder deeply enough yet. I was wondering about the design. My father in law was asking me about the return spring and I have said there appears to be nothing on the slave cylinder and I assumed it was built into the pedal assembly in some way. The detail you have put above is interesting and valid regarding the pulse return of the clutch, I've always felt the clutch is quite weighty and sharp. The clutch does feel quite different to my other car (Octavia MK2), and possibly heavier and a little more abrupt than I might expect from a 1.4 petrol. Certainly driveable though, until last couple of days. I drove it today (16 miles round trip), and the clutch felt 'not right' only once, but didn't stick to floor though. The theory of seals flipping over is interesting, and as this appears to be intermittent is frustrating. I would have expected a component failure to be less intermittent? I guessing I need to investigate deeper in and around the master cylinder to see if I can see more.
 
SEATCUPRA.NET Forum merchandise