My questions are for bleeding a slave cylinder after the line has been disconnected please. I have a 200 4 cylinder 2.5 engine with a 4 speed with an overdrive manual transmission. When a quick connect line has been disconnected and the clutch peddle has been pressed multiple times while the line is off, is it possible to get air trapped in the master cylinder or line? There has always been fluid in the reservoir. Also when the line is back on and when you gravity feed the system is the clutch peddle pushed in or is it not applied. I do not understand how the check valve works when the line is off or on. lastly what is the best way to bleed the system when all is connected? I understand that you may have to remove the master assemble and bench bleed if you have air trapped in the the system. But with the check valve on the disconnected line would I have to bench bleed the master cylinder? I have watched videos and the questions I have are related. thank you very much.
Curious why you disconnected the lines?
The quick disconnect fittings work like this: They are spring loaded and self seal with plastic seals when disconnected; or they should, but sometimes the plastic seals get stuck and do not spring closed, so watch out for that. You can see the plastic seals inside the lines when you have them disconnected. The line from the master usually has an off white seal, you should not see space between its edge and the brass colored fitting. The slave usually has a black plastic seal, though it may be white, and that should be butted directly against a small metal circle in the center of the slave's brass fitting. When the brass colored fittings get pushed together, the metal tab in the center of the slave fitting pushes the plastic seal in the master line's fitting open, and the seal in the slave fitting gets pushed open simultaneously by the master fitting, now fluid can pass through. A spring in the circumference of the master line fitting locks the two brass colored fittings together.
If they properly sealed when you disconnected them (you'd know if not because brake fluid would continue to stream out from a connection- if that did not happen, you should be ok.
Generally between the slave and master, the slave usually fails first, in my opinion. I have yet to actually have a master fail. The fluid feed fitting and bleeder have o rings to seal them to the slave body, with small cross pins holding each in place. They can leak both where the feed line enters, and where the bleeder line enters, at the o rings. I have had this happen a number of times. Sometimes you don't see a fluid drip, just a tiny bit of wetness where these lines enter the slave. This can 100% cause clutch disengagement issues. I had another slave that leaked from the body itself somewhere, never saw fluid until I dropped trans and then the whole underside of the slave body was very wet.
Your master should not have to be rebled, provided the fitting on the line closed when you disconnected it from the slave. With the master disconnected from the slave, see how much play you have in-and-out on the pushrod going from the clutch pedal to the master cylinder. I believe you want no more than a 1/16" play in that pushrod before you can't push it anymore, hope someone else can confirm that number. With the clutch master disconnected from the slave, you shouldnt be able to push the clutch pedal down really at all, other than the play I mentioned. it should feel like its hydro-locked (because a bled one basically is, there is nowhere for the fluid to go if you push it with the pushrod, unless its air bound, or leaking).
Sounds like you might have air in the master since you are saying you can pump the pedal. Are you saying that with the master disconnected from the slave, you can pump the pedal? Just wanna make sure I read that right
On the best way to bleed the system: there is no great way. Sometimes it will just fight you the whole time. There are a lot of kinks and bends in the assembly that air pockets love to get stuck in. Forcing air downhill is a pain since it is lighter than brake fluid and wants to rise. My best one-person method for in-truck bleeding is this: gravity bleed to start. Then with slave/master connected, pump pedal at varying speeds a dozen or more times. Put a pipe between clutch pedal and seat. Get under truck, pop bleeder open and quickly shut it. Since the pipe is holding the pedal down, you will not suck air in. If the pedal was released with bleeder open, it would be possible to suck air in.
Repeat this process for half an hour or more depending on how much air you might have in there. For master/slave that do not leak, this will bleed the system eventually, I have done it this way in-vehicle a number of times.
If you cannot get clutch to disengage or truck grinds gears, its likely you have a bad (leaking) master or slave in which case replacement is the only fix
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