clutch flush question

[NissanMaxima]

Hi all:
I had to remove the air intake assembly to get at my throttle body plate for cleaning so thought this might be a good time to flush the clutch fluid on my 95 Maxima. The car has two bleeders - one down by the manual transmission and the other by a strut tower on what they call the "clutch piping". My factory service manual specifies alternating between the two locations several times and using the standard technique of having an assistant pump the clutch pedal, hold, opening and closing the bleeder valve, and then repeating the cycle. However, after opening and closing the bleeders, the pedal would remain at the floor at would have to be manually pulled up for the next cycle. I thought perhaps this would improve after several cycles/iterations between the two locations, but it would always remain at the floor for the entire procedure - I alternated locations probably 5x and 2-3 cycles at each location during the procedure. I was looking at some Youtube videos (not for a Maxima) and one video said the pedal can remain at the car but should eventually return to the full up position at some point during the procedure when they say something about depressing the pedal 5x to "push out the concentric slave cylinder piston" which I didn't understand since the assistant would pump the pedal each time at least 3x unless we weren't pumping it enough. But other sites seem to indicate on some cars you will always have to manually pull the pedal back up. Does anyone know whether the pedal should return on its own for my car and what I might try to achieve that? My factory service manual says nothing about having to manually pull up on the pedal. I will note that during the bleeder open/close phase, I wasn't sure if it should be opened in just a short burst, or allowed to remain open for a few seconds.

pages CL4 and CL5 for those interested:
https://www.nicoclub.com/FSM/Maxima/1995/cl.pdf

 

[Dave Sherman]

When I flushed the clutch on my '04 CR-V, the pedal remained at the floor doing it the 2-person way. No problems after I pulled the pedal back up.

 

[mk378]

Since you aren't needing to remove air you don't have to pump fluid through. Leave the pedal up, open the bottom bleeder and let old fluid come out by gravity or use pressure or vacuum equipment if you have it.

 

[NissanMaxima]

Originally Posted by Dave Sherman
When I flushed the clutch on my '04 CR-V, the pedal remained at the floor doing it the 2-person way. No problems after I pulled the pedal back up.

Thanks Dave. So you had to pull it up after each cycle for the entire procedure? You confused me when you said no problems after pulling it back up, or perhaps you meant after the final cycle.

 

[NissanMaxima]

Originally Posted by mk378
Since you aren't needing to remove air you don't have to pump fluid through. Leave the pedal up, open the bottom bleeder and let old fluid come out by gravity or use pressure or vacuum equipment if you have it.

Thanks... I was wondering if I could do this via gravity drain like I just did with my brakes. Also, I think I saw or read that you can put a hose in a filled bottle and pump away!

 

[mk378]

Air will get in around the bleeder threads. If you're pumping the pedal you really need to close the bleeder before each "up" stroke.

 

[NissanMaxima]

Yes. I was careful to close the bleeder before having the assistant pull the pedal back up for another cycle. I wonder if it would help open and close it faster though. The burst of fluid out was very quick and then just slow drops for the next 2-3 seconds.

 

[mk378]

The reservoir is blocked off from the system unless the pedal is all the way up. Holding the pedal on the floor with the bleeder open is expected to yield no fluid, it can't get out of the reservoir.

 

[NissanMaxima]

I confused with what you are trying to say. It did flow from the bleeder and drain the reservoir with pedal pumped, held down, then open bleeder as pedal is held down, just as it shows in my factory service manual I linked. After the fluid flowed from the valve, I would close it and the assistant would then have to pull the pedal back up for another cycle (just to be clear how I did things). That page from the FSM I link does say to repeat the cycles until "brake fluid flows from the air bleeder valve without air bubble" and that is under the conditions of pedal held down, bleeder open.

As soon as I opened the bleeder, fluid would spurt out (in both locations depending on which bleeder I was working on). In fact the system seemed to flush quite well and I got out some dark fluid and had to continually watch and refill the reservoir during the process.

 

[28oz]

My 300ZX has a very similar or same setup. It can be very tedious. I find I have to manually work the slave cylinder on the transmission back and forth to work the air out of it in addition to using a mityvac on the bleeders. This would have to be done a dozen times or more. If you've only done it a half dozen times, you may be just getting started, lol. Of course, I had replaced the slave cylinder at the time, so I knew there was air in it. Be patient and keep doing it.

 

[NissanMaxima]

Well the thing is, I'm not sure if it is supposed to return to up position by itself after closing the bleed valve and releasing your foot. When I pull it up, it depresses AND returns to up position by itself as many times as I like before the next cycle and feels just fine and everything was working flawlessly before this which makes me think no air, and therefore this is supposed to happen during the procedure. On the other hand, I find it odd my factory service manual (pages linked above) doesn't say anything about having to pull the pedal back up after each cycle.

 

[mk378]

Most cars only have a weak spring to return the clutch pedal up. Normally the big spring in the clutch cover pushes it up by working backward through the hydraulic system. The little spring at the pedal is to make sure the master cylinder comes all the way back out and the pedal doesn't rattle. It may have an "over center" design so it has little effect when the pedal is down.

 

[mightymousetech]

Pressure bleeding makes this 1000x easier.

 

[NissanMaxima]

Originally Posted by mightymousetech
Pressure bleeding makes this 1000x easier.

In terms of having the clutch pedal return to up position each time without pulling it up, or removal of more fluid faster due to vacuum?

 

[mk378]

In a pressure bleed you don't have to move the pedal at all. Pressure applied at the reservoir forces fluid down through the system.

 

[NissanMaxima]

Ahhhh... I see... just like using a vacuum system to bleed brakes. Thanks

 

[cronk]

My chevy cavalier wouldnt return on its own during bleeding either, it had an "over center" type spring so it didnt start pulling the pedal up till you pulled it up half way by hand.
Once it was bled, it worked fine.

 

[NissanMaxima]

Thanks Cronk. So at some point during the procedure though it did start returning up on its own? I was doing this as maintenance and didn't have the system open, so I saw just a few tiny bubbles here and there, and long after I saw the air after many more cycles, the pedal would still not return up on its own until I basically just closed up shop and posted my question here. Pedal works just fine when you are pumping it and getting it ready to open the bleeder. It is just after immediately opening the valve with pedal depressed and then closing the valve, it remains at the floor.

 

[TurboTravis]

I typically 'reverse bleed' these by using a large syringe and forcing fluid thru the bleeder.

 

[cronk]

Originally Posted by NissanMaxima
Thanks Cronk. So at some point during the procedure though it did start returning up on its own? I was doing this as maintenance and didn't have the system open, so I saw just a few tiny bubbles here and there, and long after I saw the air after many more cycles, the pedal would still not return up on its own until I basically just closed up shop and posted my question here. Pedal works just fine when you are pumping it and getting it ready to open the bleeder. It is just after immediately opening the valve with pedal depressed and then closing the valve, it remains at the floor.

No, it would never return on its own once the bleeder was opened. Just bled it several times until I wasnt getting any more air and called it good.
With the over center type spring, the system relies on the pressure from the clutch pressure plate to push the pedal up to the point the spring can take up the last couple inches.