Yaris 2011 Clutch pedal problem (1NR-FE 1.33 6 speed engine)

[Mark_C]

Hi all,

Our Yaris is now off the road having developed a clutch problem whereby the clutch pedal feels really light to press down and the gears will no longer engage. Prior to this there have been no issues with the clutch whatsoever, this issue seems to have happened very suddenly on one car ride back home when I started noticing a weird change in the clutch pedal and I was struggling to get in to gear. Luckily managed to get back on to the driveway before the gears completely crapped out!

I have bled the clutch/brake fluid and air bubbles come out with what looks to be a dark gritty looking fluid - not good at all. After doing this, resistance returns back to the pedal and I can then shift normally again but after a week it just goes back to how it was and the process requires repeating again so evidently there's something wrong.

Doing research it could be the master or slave cylinder, except this model seems to have no slave cylinder?? Looks like it hosts something called a CSC that acts like a slave cylinder? Any clues on what I should be looking out for? I can't find any service manuals for this specific version of the car, only the older 2006-2008 car with what looks like the old classic external slave cylinder. Any help would be most appreciated.

 

TIA,

Mark

 

 

 

[flash22]

CSC stands for Concentric Slave Cylinder - are you loosing brake fluid, note, there is a divider in the master res if you don't keep it slightly over full the clutch side does not refill

 

[Cyker]

The CSC is basically a slave cylinder combined with a release bearing, and if it hasn't been changed for a long time the rubber seal that lets it move in and out may have degraded. Do you know when the clutch was last done? If it was changed without changing the CSC it could be worn.

As flash says, check the hydraulic reservoir first tho'. Maybe see if there is any evidence of drips or fluid under the car too.

[Mark_C]

Thanks for the responses! From what I've seen so far, I don't appear to be losing brake fluid. I noticed that the fluid level in the reservoir was exactly on full so I've filled it to just a bit above that. I'll keep an eye on the fluid level and see if it moves from where it was. I've bled it again and finally managed to get stiffness back to the pedal but I have a feeling after leaving it it'll just go back to how it was. 😞 

Regarding the clutch age, as far as I'm aware I don't think it has ever been replaced since the car was bought when it was second hand in 2013. It only has 45000 miles on the clock so hasn't had a hard life.

[flash22]

I would suspect the clutch master has failed, no pressure and no fluid loss is a failed seal

[Stevie J]

The Clutch runs from the same fluid reservoir as the brakes, which is mounted on the brake servo unit. If this reservoir is anything like the Mk2, it has 2 separate compartments within it, and the clutch reservoir is at the back of the main reservoir. I think they do this so that if the clutch line loses fluid, the brakes side of the reservoir wont then also run dry. When you look at the reservoir from the front, it actually looks full, so you can be fooled into thinking the clutch has plenty of fluid, but in reality, the rear part of the reservoir could be empty. There is a divider in the main reservoir that comes almost to the top, and the brake fluid has to be full before it overflows into the side for the clutch system at the rear of the reservoir. I found that out when I was trying to bleed the clutch on my old Mk2, to try to get the biting point to be higher than about an inch off the carpet. If the rear part of the reservoir is not kept full, it can empty during the bleed process and introduce more air into the clutch master and slave.

2011 was the year the Mk3 came out and also could be the end of the Mk2 run, ie, you could get both the mk2 and mk3 in that year, but as the late model Mk2 (2009 - 2011) had the 1.33 6 speed box, I imaging that it has the same setup as the Mk3, which is the clutch slave is concentric and the only way to change it or get to it is to remove the gearbox from the engine. If the slave has been leaking it could well have contaminated the clutch linings.

I'd imagine the first port of call would be to replace the master cylinder behind the clutch pedal first, as this would be cheaper to do, and if this doesnt work, then there would be no other option than to have to get the gearbox off to get to the concentric slave / thrust bearing, and if that was going to be done, it would make sense to replace the clutch as well.