Toyota Clutch Pedal staying down

toyota
cylinder
pedal
clutches
fluids

#1

My Toyota J150 based 5 dr mid SUV ( Badged as Prado)with a hydraulic clutch at 85,000, 109,000 and now at 133,000 Km exhibits a clutch pedal that sticks down on the floor and has to be manually pulled back to regain clutch operation. The clutch is engaged when the pedal is on the floor hence causing a dangerous condition as the driver cannot disengage the clutch due to no further pedal travel being available.



The first time the dealer changed just the fluid , the second time the master cylinder and the third time the master cylinder.



They now say there may a mechanical interaction with the actual clutch mechanism “to cause a deterioration of the master cylinder seals by vibration”.



I have a tough time following this and feel the problem is more likely the condition of the fluid or bad seals or something else.



Help please - I’m now being asked to pay for a full clutch replacement ( no other symptoms of clutch deterioration at all) when I consider this may be un-necessary - anyone else got a sticking clutch pedal ( On any hydraulic type system ?



Thanks

A




#2

All of my Toyota’s have done this when the pedal pressure fails. What year model is this Prado?

Is there fluid in the master cylinder reservoir? An empty reservoir is usually the cause of this problem. In my case, I had a bad seal in the slave cylinder that let air leak into the system as the pedal pressure was relieved. If enough air gets into the system, it will compress when the pedal is pushed down and absorb the pressure, allowing the pedal to hit the floor.

I’m surprised the dealer has replaced the master cylinder, but not the slave cylinder. Since they work ideally together, and wear together, they should always be replaced together. This was the case for my Supra. Replacing both together fixed my problem, and I haven’t had a single clutch issue for the last 2 years since.


#3

Thanks for response
Prado 2003
Full fluid level in reservoir
No leaks in the system anywhere
Happened when cold and hot
Your suggestion to change slave cylinder too is MUCH better than a new clutch.
Full service history on the vehicle indicates no clutch probelms until 85,000 when fluid was changed and all was well for 25,000Km
TOYOTA itself say "Havent heard of this problem before !!"
the more I ask around the more anecdotal informnation I get that people have experienced this but the real technical answer as to WHY it is happening is still illusive especially with the changes indicated the problem actually goes away for around 25,000 Km each time something is done.


#4

Further input to your answer.

The symptom of air in the system being compressed is not my case as once the clutch pedal is manually pulled back to its normal engaged ( pedal up) position it can then be operated normally until abruptly once again the pedal sticks down,but the clutch is engaged .

This not the mushy pedal feel when hydraulic fluid is contaminated or when air is in the system. The clutch either works fine or suddenly after disengaging normally you change gear and release pressure on the pedal, the clutch re-engages but the pedal stays on the floor. What I think is happening is that fluid is passing the master cylinder piston seals and the piston has to be manually returned to its normal engaged position in the cylinder by pulling up the pedal and forcing the fluid back to where it should be to then allow normal operation again until the problem happens again.

What I cannot undertand is why the seals would fail to an extent to allow fluid to flow past them after only 25000Km.

Is this a pressure problem back from the clutch itself ( the pressure required to operate the clutch has not changed noticebly in 133,000Km), is the fluid is getting contaminated and causing the failure of the seals, is there a problem of bad seals on this clutch master cylinder ,?.?.?

Tks


#5

Some of these clutches are difficult to properly bleed. This was the case for my old pickup. I thought I had it completely bled after changing the master and slave cylinders, but was coming to a red light a couple of days later and the pedal dropped to the floor. I pulled the pedal back up, and it hasn’t recurred since. I kept that truck for 7 more years, and no other incidences.