Replacing clutch master and slave help

Well that could be part of the problem. I guess I’m still confused by the feel of the master cylinder. It doesn’t feel like there’s a seal to draw fluid in. I can move the pushrod with just a finger and the replacement cylinder I bought feels completely different. It’s much harder to depress the cylinder and it returns on its own and there’s no return on mine whatsoever.

so when trying to bleed the system, it doesn’t feel like the master cylinder is even pushing fluid around.

 

Now I'm confused. Are you trying to install/bleed the old one or the new one?

 

I haven’t replaced the OEM one but I bought a replacement to see if it felt any different

 

Install the new one, bleed it properly.

 

https://photos.app.goo.gl/2rhYrv3vWpxFfKGJ8

Here's a video showing the behavior of the installed master cylinder currently.

 

Replaced the master cylinder and successfully bled the system. I’d still be interested to know if the master cylinder was actually bad but it’s at least back to working condition.

Successfully replaced it without taking the clutch pedal assembly off but man was it a pain in the asssssss to do.

 

My son's 2005 has the "dual wall MC reservoir". When the clutch master cylinder failed and started leaking on his truck and we researched it to see what was going on, my understanding was that the idea was to preserve the fluid level for the brakes in the event that the clutch system developed a leak and emptied itself. The clutch fluid reservoir wall in the center of the fluid container appeared to be a bit higher than the brake fluid reservoir section. Thus I believe the idea is that it can drain down to empty the (the clutch portion) and not take the brake fluid down with it during the process. Good engineering? Dunno.... more like over-engineering? I had a vehicle with a hydraulic clutch: It had it's own stand-alone fluid reservoir. We spent a fair amount of time looking for same on the Tacoma before doing some research and resolving the mystery. Tacoma's also do not appear to have a dual master cylinder set up for the brakes (I can't swear to this though): something that I thought had been standard on everything for years and prevents losing both the front and the rear brakes if you lose a line to any individual wheel. For example, Volvo employs a dual diagonal hydraulic system: lose a line and you still have three brakes available and always two on either axle.

 

First I’m hearing actual details on this and I like KNOWING the why. Thanks for sharing @Williston

 

Did you top the center cylinder off with fluid and closely monitor every 5 pumps? How are you bleeding it, do you have a check valve down below, or are you doing the open-press down on clutch/close-pull up on clutch technique (which I recommend as it’s fail proof if done right).

Are there any fluid leaks anywhere?

is vehicle parked on concrete, grass, gravel or dirt?

Do you see fluid spots on ground?

How much fluid have you put into the system yourself?

what type of fluid are you using?

with the vehicle on do the brakes build pressure or do they sink to the floor?

do you have TWO fluid reservoirs or one?

devil’s in the details man. Happy to help but not replying until all these questions are answered

 

Nvm, you got it! Good job!!

total pain in the ass to replace the MC the first time you do it, after that you realize it wasn’t so bad. Just sucks that everything appears to be rotated clockwise 90d from the nasty kink in your neck for the next day or so.

 

Yeah it was not too pleasant. This morning I had some weird behavior though and not sure if it’s related. Driving twice the engine cut out and now I have the check engine light on as well as the slip control warning light. Any ideas what might be going on? Really don’t wanna go to the stealership to find out what’s up

 

Same here! It was mainly a mission to find out where the clutch reservoir was as in my experience, a hydraulic clutch always had it's own dedicated
fluid reservoir. The dual set-up really surprised me as the plumbing to it doesn't make it real obvious that's what is going on.

Too add: The slave cylinder blew a line and failed about 40,000 miles later. I'd recommend replacing both at the same time. The old master cylinder was a nylon-plastic looking material and was dripping fluid just before it went out. The new one is metal. It took about three weeks to get the part from Toyota. The dealer took responsibility and gave him a loaner. We looked for one but no one had them.

 

Now I’ve got even weirder things going on. I had a local mechanic connect to the OBDII and it was throwing a crank sensor error which made no sense so he reset it. Now when I’m driving, the engine will sporadically cut out and I have to pull over and restart the truck. This has happened probably 5 times today but not at all the day before after I finished the swap. I didn’t unplug anything besides the clutch sensor in the cab and a blue sea fuse box I installed a while back but I put that all back together the same as it was previously. I didn’t touch any other electronics so the behavior seems very strange. The real problem I see is that I can’t just take it to a shop to diagnose because it’s intermittent and I’ve been unable to replicate the problem intentionally. Any ideas what gremlins I could have let loose in there?

Are there any faults that the factory response is to cut power to the engine? That seems low likelihood but I don’t know if anyone has more insight.

 

From what I recently heard from Gadget, if your battery’s voltage drops below 9V the crank sensor does exactly what you’re talking about. Someone please feel free to correct me on this.

check your starter wires for exhaust burns/shorts, check your battery voltage levels (though from my experience these things won’t crank without at least a steady 11.7V - understanding that voltage alone doesn’t represent battery health, which auto stores can test for you).

Fucking Gremlins.

most importantly - retrace ALL steps you took for the repair and look for out of place things, loose connectors, wires damaged from brake fluid (which will strip away certain materials/plastics). Best of luck hunting!

 

I switched my scangauge to monitor the battery voltage and it was 13.7-14.1V the whole time so I don’t think it’s dropping below 9V and causing the engine to cut out. I took it into the stealership and they couldn’t find anything with their diagnostic tools and they drove it but couldn’t replicate the problem. Not really sure what to do from here so any help is mucho appreciated

 

Well after a lot of troubleshooting with the dealership, it turns out that the stalling and engine dying is not related to the work I did replacing the master cylinder. It was related to the lighting system I installed a long time ago and some shorting that is happening when I push the shifter forwards (1st, 3rd, 5th gears). I'm going to be doing some rework this weekend to correct it that I'll write up but thankfully it's not something more serious.

 

Loving this.. nice resolution, was going to mention checking for shorts as I found one the other week (battery cable vs header = intermittent shorts) but have had tranny out fixing other issues and haven’t had time to re-work that to see the resulting performance (does it still hesitate when under significant load change).

 

This thread seems very good (though I'm glad the off-topic electronics talk is over..?)
What may not be obvious in diagnosis....when we think clutch might have "air in fluid" OR
clutch pedal (motion or lack of motion!) is just STUCK all the way down but why,
we may tend to misdiagnose.
Hope I'm not wrong saying that "air in fluid" is mostly/always? an install-new-parts problem,
not something that develops normally, i think, unless the fluid lines let go and leak.

On my gen2/2006 Tacoma, mine's 4cyl 2.7...assuming/hopefully same setup on manual trans 6cyl gen2,
yes my master cyl lives in the pedal assembly and takes fluid from the brake reservoir via rubber hose.

I scratched my head alot while replacing a 17 yr old master and slave, when my taco developed
the classic "pedal sticks all the way down" problem. What I think I learned:

Spoiler: I'm saying the slave cylinder is the primary suspect...w/ dirt and rust, its piston ends up seizing/sticky/stuck.

Confuser: the pedal assembly spring is interesting, with a spring applying different forces depending on position.
Like any other spring setup you'd think, more travel = more spring force? Not exactly: at the bottom 1/3 or so,
I observe the spring no longer adds MORE force. TMI/trivia? it feels odd/weak if free, but that's NOT a problem,
it's a design feature, somehow the spring has achieved it's max-force-up with pedal halfway or 2/3 down.
Which actually adds up to a smooth feel, since the pressure plate adds plenty of force-up around halfway down.

My first thought when pedal stuck down: perhaps the pedal assembly needs attention,grease,something.
I loosened the 14mm LH-side bolt-head a bit, way up high (i think RH-side nut is welded to pedal assy)
just a half or whole turn/thread, thus loosening the bolt the pedal pivots on.
But this accomplished nothing, the pedal wasn't bound at all by tightening, so I tightened it back and moved on.

There's 3 or 4 things contributing to the clutch pedal's desire/ability to come back up.
Below, I'll start "bottom up" and try to ignore the pedal assembly, which lives a sweet/rust-free life in the cab.

Thing1: the pressure plate "fingers" I'd say exert the most force in this equation.
The fingers, when depressed (pedal down) by the slave cyl and fork, start an obvious pushing war
which ends, normally, when you release the pedal.
UNLESS! Slave cyl is rusty and its piston gets jammed "engaged",
so until/unless you crawl under and hit the fork,etc to un-stick the slave
after trying the easier/faster "pull the pedal up" w/no luck, you may need to get towed.
Carry a rock or hammer if you're suffering erratic stuck-pedal behavior,
learn to crawl under and tap/hit the fork back towards the cylinder when stuck, until you SOLVE problem.
Even this "fix" (awful temporary fix) really sucks w/danger if you got stuck at a red light in real traffic.

already mentioned slave as likely problem, but I'm back to describing spring-back contributors.
Thing2: slave cylinder may have an internal spring, but I forget.
My old slave got so rusty (removed, on bench) I can't move it by hand to feel a spring fighting back.
Then again, there's no adjustment HERE, it's self-adjusting so I'm ignoring or questioning the spring-back on slave.
BUT THIS (slave) IS THE THING living in rusty hell, with a rubber boot that's not going to keep
rust and dirt from messing with the slave cylinder and its piston which lives an inch inside/away from the boot.

Thing3, the master cylinder definitely has an internal spring, so it WANTS to return fully on release.
BUT! if things/slave is/are stuck, the fluid doesn't want to move either (won't allow master cyl to return/release.)
That's why the pedal sticks down! But here's where I get most confused:
Pedal seems designed to catch happily/magically to the master cylinder shaft+tip....
(I don't know which type "tip" I have, see interesting diagrams above in this thread show types A,B,C)
but I suspect all the tips seat and catch the pedal somewhat when installed (no strong catch, no lock nut/etc to pedal).
I never did figure out why/how...when stuck down, pulling pedal back up ALSO seemed to pull master shaft up too.
All I can say is, it's kind of like a tug of war with various things contributing to the release.

Thing4, the pedal assembly has spring-back, but it seems NON-problematic once you understand its spring setup.
You don't need to remove the assembly and I wonder if there's a 3rd and/or 4th upper bolt/nut,
since I could only see 2 hex nuts near the bottom of the assembly. You DO have to suffer hell
messing with the rubber hose and pinch-clamp for the fluid feed, and another hell
re-threading the steel fluid line onto the new master. Consider not doing both, if slave is old and the problem!

And as told in other posts on this thread, after solving any terribly-stuck problem and replacing either/any cylinder,
check or re-do the adjustment on the master's shaft, so you will have FULLY released everything with pedal up. (Avoid allowing throwout bearing to touch pressure plate fingers)
You should be able to hear the bearing spin up and START to touch/engage, with driver door open before driving away, as you touch the pedal in its first few inches. Crawl under and get a helper to touch pedal while you listen and watch the fork move, also!

Shown/attached/inserted, are my original slave cylinder and master from 2006 Tacoma.
Pardon the confusion here. Appreciate the OTHER wisdom from prior posts.

 

I replaced the master on my 08, wish I had done it sooner!

 

Wet floor under clutch...
THis is very helpful!