Pressure plate bad? (clutch cylinders/stuck 1st/pedal slow)

[One Sick Puppy]

Ok, I've read a couple of threads but not sure I understand how to eliminate options. Original symptom which happened a couple days ago was the clutch pedal wasn't returning consistently - sometimes not fully, sometimes stuck to the floor. The push to the floor has always been good - lots of tension, but return seems to vary.

With that said, I removed the return spring on the pedal and I thought that had fixed my problem, but it still gets stuck(ish) and doesn't always return with the same pressure/force. Sometimes it feels like it only returns half way. Removing the spring didn't seem to change the feel of the pedal so I'm fairly certain the return spring and bushings (almost completely worn) were bad. But, I read that it shouldn't affect the functioning of the clutch.

The main problem is that I can't shift into 1st gear sometimes. It's intermittent but while idling in my driveway, I did a bunch of experimenting and found that whenever I could get it not able to shift, it would always be followed by the pedal return pressure being much weaker.

Youtube taught me that I can test for slippage by trying to start from 2nd gear from stop and sure enough, it stalled. I've never found the clutch to be weak or slip. Power seems to have always been good.

Clutch fluid level is high, but not particularly clean.

Never replaced a clutch before. Prefer not to, but don't mind if I know I have to. I thought maybe pressure plate is bad, but seems to work fine most of the time... would that be intermittent? Is it possible the clutch or slave cylinders are bad without leaking? I guess the clutch isn't always engaging fully, for some reason, but when it does it holds fine.

Thanks for any pointers. Only use this on road as DD. Stuck sharing the Sienna with the wife, now. :/

 

[nissanh]

Engine off. Pull park brakes. Choke wheels. Ask someone to press the clutch and at the same time, slide under the transmission and check the pushrod movement. Ask to release the clutch and check how pushrod moves. If you have a faulty pressure plate (I doubt it if it is OEM), you should be able to push the pushrod back into the slave cylinder by your hand if the pressure plate has no return force.

How old is the clutch master cylinder and slave cylinder? When did you last flush the hydraulic system?. Recently the return spring inside my car's clutch master cylinder broke (after 30 years of service life 285K miles). Use OEM AISIN/toyota parts when replacing any older part.

 

[One Sick Puppy]

I've never done a clutch flush since I've owned it - about 7 years, ~100k km/60k miles I think I have all the receipts from the previous owners and no clutch or fluid changes so good chances the clutch system hasn't been touched in 22 years (2000 model). Just passed 300k km (180k miles) on the ODO.

I'll see if the wifey can help me with what you've asked. *cringe* Not sure I'll make it out from under alive...

 

[Bad Luck]

If you had a bad pressure plate you will have reduced clamping force on the clutch causing clutch slippage. A bad slave cylinder or master cylinder can cause a weak pedal return. A removed/weak clutch pedal return spring will also cause a weak pedal return.

Based on intermittent not going in gear I think you have a master/slave cylinder issue. When it doesn’t go in gear does it feel like the clutch isn’t disengaged from the flywheel?

 

[One Sick Puppy]

Based on intermittent not going in gear I think you have a master/slave cylinder issue. When it doesn’t go in gear does it feel like the clutch isn’t disengaged from the flywheel?

Yes. I believe I did notice that’s how it felt. Like something beyond the peddal was stuck and still engaged.

 

[TucsonMike]

I had similar symptoms and it was my clutch master cylinder or slave cylinder. U can try bleeding it first but if u have a lot of miles on it I would replace those first.

MikeM

 

[Sparky 97Runner]

These are symptoms of a master/slave issue but I'm a little surprised that you don't see any leaks. Even the smallest leak in the hydraulic hose will give these symptoms. If you're sure that the hydraulic hose is not leaking I would start by changing out your master, slave and hydraulic hose. Rockauto sells these three Aisin parts for under $100. The way I see it you want to change these three items out even if you end up replacing your clutch.

 

[Sparky 97Runner]

i'll see if the wifey can help me with what you've asked. *cringe* not sure i'll make it out from under alive...

engine off!

 

[One Sick Puppy]

I'll take a better look tomorrow to see if there are any leaks. Seems like a good investment to replace those before the clutch and see what happens.

 

[nissanh]

Do a good search on ebay. I got my OEM toyota AISIN clutch master pump for $33! which is a steal! It was sold as NAPA part in their box, so check with the seller and ask for "AISIN" stamped on the body.

Check the master pump of yours, especially the design of the pushrod and length. Some years may not have a damper attached to the pushrod and/or the length varies. (happened to my car's master cylinder).

 

[One Sick Puppy]

I spent a bit more time investigating this morning. I don't see any leaking fluid anywhere in the clutch lines and the level seems good. I did get it to lock up once while I was tested in my driveway. This time it locked up and I couldn't get it out of gear... I think it was reverse. Had to mash the pedal a bit as it seemed stuck, also. ...

I'm trying to understand how the master or slave could be broken but not leak? I don't mind replacing these items, tho...

 

[Bad Luck]

I spent a bit more time investigating this morning. I don't see any leaking fluid anywhere in the clutch lines and the level seems good. I did get it to lock up once while I was tested in my driveway. This time it locked up and I couldn't get it out of gear... I think it was reverse. Had to mash the pedal a bit as it seemed stuck, also. ...

I'm trying to understand how the master or slave could be broken but not leak? I don't mind replacing these items, tho...

The master has internal seals that can leak causing fluid pressure and volume to go back to the reservoir instead of the slave. I recommend replacing the master, slave, and soft hose.

 

[JohnMc]

If you had a bad pressure plate you will have reduced clamping force on the clutch causing clutch slippage. A bad slave cylinder or master cylinder can cause a weak pedal return. A removed/weak clutch pedal return spring will also cause a weak pedal return.

Based on intermittent not going in gear I think you have a master/slave cylinder issue. When it doesn’t go in gear does it feel like the clutch isn’t disengaged from the flywheel?

/\ /\ /\ If it's not slipping when you get the pedal to come up, then I wouldn't be worrying about what's going on in the bellhousing.

FWIW these symptoms sound EXACTLY like what I had happen with mine a few years ago. No leaks, no problems with the clutch itself, but I started getting an occasional 'slow' pedal return. Progressing until it occasionally stuck down and I had to tug it back up with my toe.
I bled it a couple of times, fresh fluid, no real improvement, so I replaced the clutch slave cylinder thinking it was sticky, not it. Then I replaced the clutch master and that was 100% it, clutch worked perfectly after that.

 

[One Sick Puppy]

Firstly, thank you all immensely for your help and suggestions!

I went ahead and bought new Aisin master/slave cylinders as it wasn't particularly expensive. When I got some time to do the job, I actually noticed that the fluid level was indeed a tiny bit below the minimum level. I didn't realize the min/max difference was so small. Anyhoo, I topped up the fluid and took her for a drive but still had the problem. So, I went ahead and swapped the cylinders. Wasn't a difficult job at all so no regrets. Pedal seems to be better but I can't say for sure as the problem was fairly intermittent. I'll have to drive it some more.
However, after doing all that work, it occurred to me that I should have given the system a good bleed and fluid refresh before doing the work. My slave was dry - no fluid in the boot. Both old cylinders seem fine.

All said and done, I wonder if I simply had a little air in my lines or the fluid was old and needed replacing... anyhoo... I'll update again in a week or so after I've done some driving.

Found both my sway bar link ends were broke, tho... I suspect they've been like that for at least a couple years, if not more - they are pretty crusty.