Clutch suddenly not disengaging after high revs

[Hendrix]

Hi everyone,

New to the forum and trying to utilize your combines knowledge of our beloved (or hated, depending on your experiences) Yaris.

Basic info: 1.33 VVT-i, 100 Hp, [SCP9_, NSP9_, KSP9_, NCP9_, ZSP9_], MY: 2010, motor code: 1NR-FE
Manual 6 speed gearbox, start-stop.

To the point: My Clutch suddenly stopped working (no longer disengages) after driving away from the traffic light.
I was driving away fast (pushed off the road almost by a dodge RAM that wanted to cut me off... david vs goliath ) and I let it go almost into the rev limiter in 2nd gear and then suddenly the clutch did not disengage anymore and have been driving the rest of the way home without a clutch.

My biggest problem now is finding the point of failure, I have bled the clutch until it seemed empty (pedal was totally lose) and then reverse filled it up again. (from the bleeding valve pushing the brake oil in with an oil can). Did not help. The pedal feels normal again but the clutch is still not disengaging.
I did not find any drops of fluid under the car either so seemingly no leak.

Sadly I do have a CSC (concentric slave cylinder) that is located inside the clutch bell. (so if it leaks, it probably will leak in there...)
So no easy checking or replacing of the slave cylinder.
Having everything replaced will be about 2500€ = ±3000$ which is basically half of the value of the car right now.

So I will have to do it myself hence about 1800$ is labor costs, but being a single dad with 4 small kids.... having time (and money) is a luxury.

And before I start taking the whole transmission out to reach the clutch and the slave cylinder:

Can anyone point me in the direction of the most likely point of failure and how to check this (hopefully easily)

You will have my eternal gratitude.

Hendrix

[Leegamer]

So does the pedal still go down to the floor even though it won't disengage or does it have resistance?

[Hendrix]

Originally Posted by Leegamer

So does the pedal still go down to the floor even though it won't disengage or does it have resistance?

Yeah, it feels like it works normal.. although I do not feel a certain point of where it should disengage, there is no difference in resistance when pushing down (after the initial free play of about 1/2 inch)

After bleeding it almost empty until it did not push anything out anymore, the pedal was very lose and easy to push down, I refilled it from the bottom (bleeding valve / nipple) to prevent air bubbles.

Pedal works now normal but clutch does not disengage (like before the bleeding / changing the fluid)

No drops under the car, no liquid from the reservoir disappearing...

[mirageman]

That's a tough one. If I were you, I would try to find a part of the bell housing from underneath the car that I could drill a hole big enough for a cheap borescope from Harbor Freight and take a peek in there while someone steps on the clutch. Problem is I don't think you have Harborfreight in your part of the world. After determining the cause through that hole, I'd simply tap it and put a bolt in it or just find a tight fitting bolt and with oil, go a little bit in, little bit out, a little bit further in, and back and forth until you make your own threads..... Drilling from underneath will prevent any shavings from falling into your bell. You just have to determine where you can drill safely.

As for the real cause, we know your clutch isn't disengaging, so you're looking at either a bad throw out bearing, bad pressure plate or bad slave cylinder. I am unfamiliar with the concentric slave cylinder mechanism, sorry... but I don't know how it can feel normal if it is not disengaging your clutch. Is it perhaps something that can somehow break from it's attachment and move AWAY from the pressure plate instead of pushing against it? (Like a person pushing against a wall and feet sliding backwards.)

Be real careful where you think you might drill! :-)

[zimmer]

Originally Posted by mirageman

That's a tough one. If I were you, I would try to find a part of the bell housing from underneath the car that I could drill a hole big enough for a cheap borescope from Harbor Freight and take a peek in there while someone steps on the clutch. Problem is I don't think you have Harborfreight in your part of the world. After determining the cause through that hole, I'd simply tap it and put a bolt in it or just find a tight fitting bolt and with oil, go a little bit in, little bit out, a little bit further in, and back and forth until you make your own threads..... Drilling from underneath will prevent any shavings from falling into your bell. You just have to determine where you can drill safely.

As for the real cause, we know your clutch isn't disengaging, so you're looking at either a bad throw out bearing, bad pressure plate or bad slave cylinder. I am unfamiliar with the concentric slave cylinder mechanism, sorry... but I don't know how it can feel normal if it is not disengaging your clutch. Is it perhaps something that can somehow break from it's attachment and move AWAY from the pressure plate instead of pushing against it? (Like a person pushing against a wall and feet sliding backwards.)

Be real careful where you think you might drill! :-)

My buddy got this incoming Yaris project with an intermittent clutch issue. The previous owner mentioned his son tried to replace the slave cylinder. We'll just finish installing the suspension and dually wheels on the Superduty this week. Gonna check out the bearing and slave cylinder first.

[stidnam]

Not sure if you figured this out, but you can inspect the concentric slave through a breather / inspection hole on the front side of the bell housing. A bore scope is needed though.

It's going to be one of two things I can think of - the master or the slave. If you've got a pressure gauge you can check both. For the slave there's even a procedure where you hook up a pressure gauge, apply a certain amount of pressure and expect the cylinder to hold at that.

[Hendrix]

Thanks so far for the input everyone,

As for the "camera" to check it out through a hole somewhere, I got a very cheap one but it is not so very small, I think 8mm if I remember correctly.

I have not had any time to check yet, but lets see what I can do next week, hope the weather works with me, although when nice it might be cold too, that sucks when using tools without gloves.

Sadly I do not have a hydrolic hand pump and gauges for diagnose but maybe I should invest in those or get the diagnostics done in a shop.
I was just thinking, when I disconnect the slave cylinder pipe from the bleeding valve T connection, and plug the hole with a bolt (any special thread there?), bleed it a littel to get the air bubbles out again, pushing the pedal down should be no longer possible after one or two pushes.. confirming the working of the master cylinder. If I can still push it down, the master cylinder is leaking inside and the plunger / piston is dead / worn, if I can keep pushing it half, it is damaged halfway: explaining the clutch almost disengaging when totally pushed down

Extra information I found out yesterday, I started it in reverse and the pushed the clutch and the brake and the gas pedal all at once, Gas pedal only to prevent it from stalling. and it stays running, so the clutch is almost disengaging....

I wonder how much air could be trapped in the slave cylinder, not wanting to come out, causing the clutch to not fully disengage. Any idea how to remove all fluid and replace it without air or water in it, pumping the clutch multiple times did not solve the problem.

It also seems that when bleeding the system, at a certain point, the master cylinder itself is empty (hence the loose pedal) but the reservoir not even to the minimum level (like half between min and max). So apparently it must suck in air somewhere but I have no idea where...

At this point I strongly suspect a failing master cylinder to be the cause. However I was able to create some pressure so it still does something. (otherwise I could not bleed it from the top down either = first attempt).

Lots of things to consider, if I only had gauges and a hand pump.

Well I will keep you posted on how this ends, if any of you have some more suggestions or deductive reasoning to share, please do so...

[stidnam]

The breather hole on the front side of the bell housing is fairly big actually. There's a rubber grommet in it with the entry facing downward. You can just pull the grommet out. Should be plenty of room to stick a 8mm camera.

Not sure what you'd cap the brake line with. Maybe a spare piece of crimped line? You'd certainly get a LOT of pressure back on the pedal if you did that. Worth a try.

Normal bleeding through the T piece will displace the air. I was sceptical as well when I bled mine because there's only one line into the slave. However, bleeding it repeatedly through the T piece on the front of the box does work. Given you had a sudden failure while driving, it's either going to be the slave or master that's kaput.

It's also normal for the clutch to lose all pressure during the bleeding process, similar to what happens with brakes.

How many km's on the slave cyl? Was the clutch replaced without replacing the slave at any point?

[Hendrix]

Originally Posted by stidnam

The breather hole on the front side of the bell housing is fairly big actually. There's a rubber grommet in it with the entry facing downward. You can just pull the grommet out. Should be plenty of room to stick a 8mm camera.

Not sure what you'd cap the brake line with. Maybe a spare piece of crimped line? You'd certainly get a LOT of pressure back on the pedal if you did that. Worth a try.

Normal bleeding through the T piece will displace the air. I was sceptical as well when I bled mine because there's only one line into the slave. However, bleeding it repeatedly through the T piece on the front of the box does work. Given you had a sudden failure while driving, it's either going to be the slave or master that's kaput.

It's also normal for the clutch to lose all pressure during the bleeding process, similar to what happens with brakes.

How many km's on the slave cyl? Was the clutch replaced without replacing the slave at any point?

56 000 miles / 90 000km on the clock, original clutch original slave (hydraulic concentric bearing).

It seems to disengage a very little bit. If I start it in reverse with the clutch pressed all the way down and pull the hand brake and press the throttle pedal, it keeps running.

When bleeding, I can hear the spring creaking a little bit when it pushes the fluid out, same as when engine is off and I open the hood and door and press the clutch, I can hear the soft creaking of the spring when I move the clutch pedal.

What I notices is a distinguished difference between the first 0,5 to 0,75 inch of feedback force from the pedal to the rest of the pedal travel. It feels like free play. IS THIS NORMAL????... it could be just the amount of missing pressure preventing the clutch from disengaging.. this would make the master cylinder the main suspect. As said, if the pedal would have about half an inch more travel it would, I think, disengage.

[Rich_UK]

Get a second person or your phone to record the movement of the clutch arm and slave cylinder under the bonnet as you push the peddle down to the floor is the travel on the cylinder consistent and extending at full travel possibly a good 20mm ?

if not then you have either you have air in the system, or broken main/slave cylinder all are very easy to do so can start with these for good measure :\

But chances are your clutch has had it and the pressure plate springs aren't reliving the clutch from engaging, (even if it were the clutch fork less likely, still possible) youll still need to strip it all out.

( I've Just done a clutch on a yaris 1.3 but 5 speed 2SZFE, 4 hr job)

[Hendrix]

I bought the parts from the brand LUK and had the whole clutch replaced.

Due to not having the time to do this myself outside with minus 10°C (14°F), I had it done by a mechanic known by my neighbor for half the amount the dealer charged.

The clutch was deceased, the springs (fingers) were colored blue from the heat.
There was some drag traces on the end of the spring fingers as well as on the concentric hydraulic bearing.

So what happened?
1) Given the fact that the clutch failed at high revolutions
2) and the springs seem to have gotten too hot causing the losing of their pre-formed shape.
3) considerable drag wear on the end of the spring fingers as well as on the bearing,

Makes me come to the conclusion, the bearing failed to turn at the same speed as the clutch pressure plate, causing it to get hot real quick and lose the spring shape / force of the fingered spring, causing the clutch to not completely disengage anymore.

Verdict: Yaris is no race car and it's bad quality & bad designed pressure bearing, causes it to be a bad idea to try and outrun a Dodge RAM at the highway ramp up. (Next time I will take the 1994 Volvo 850-T5)

Well anyway I have a complete new clutch, the main cylinder was still ok so I have a spare now, the rest I will dump in the metal collection waste container at the local garbage collection point. 800€ for the whole change, with a spare 150€ main cylinder in the closet (all plastic!!!! unbelievable, same as the hydraulic bearing housing).

Thank all you guys for the input... happy new year everyone!