Replacing the clutch system hydraulic components

[PickupPete65]

I asked recently of the forum members if there were any pratfalls to be aware of when changing/replacing the clutch master cylinder and the slave cylinder. I replaced both with new parts I purchased thru eBay. With both components installed, I was unable to create any significant pressure on the system, this, after numerous attempts of pushing the clutch pedal down and having to pull it back up by hand. The slave cylinder did (ever so slowly, and after 3 dozen or more pumps of the pedal) fill and the air seemed to have been completely purged eventually. I think the master cylinder is defective, but my question is, did I miss something? Am I doing something wrong?

[PwrWgnDrvr]

I asked recently of the forum members if there were any pratfalls to be aware of when changing/replacing the clutch master cylinder and the slave cylinder. I replaced both with new parts I purchased thru eBay. With both components installed, I was unable to create any significant pressure on the system, this, after numerous attempts of pushing the clutch pedal down and having to pull it back up by hand. The slave cylinder did (ever so slowly, and after 3 dozen or more pumps of the pedal) fill and the air seemed to have been completely purged eventually. I think the master cylinder is defective, but my question is, did I miss something? Am I doing something wrong?

The number one thing you likely did wrong was buy crappy parts off ebay.

Did you bench bleed the master to be absolutely sure it is full of fluid?

Back to buying crappy parts, consider these 2 truths:

1. Buy the best and only cry once.
2. If you can't pay to do it right, you'll have to pay to do it twice.

Never a problem buying stainless lined cylinders from John Geidl aka powerwagonjohn.
And, having to pull the pedal back up by hand when bleeding is normal. Its the way the system is designed.

[BigBlockTrucks]

I asked recently of the forum members if there were any pratfalls to be aware of when changing/replacing the clutch master cylinder and the slave cylinder. I replaced both with new parts I purchased thru eBay. With both components installed, I was unable to create any significant pressure on the system, this, after numerous attempts of pushing the clutch pedal down and having to pull it back up by hand. The slave cylinder did (ever so slowly, and after 3 dozen or more pumps of the pedal) fill and the air seemed to have been completely purged eventually. I think the master cylinder is defective, but my question is, did I miss something? Am I doing something wrong?

I have yet to have a problem bleeding out the clutch on these trucks.
I watched it done twice by some old timers around here. It still makes no sense to me but they repeatedly moved the pedal up and down, after 5 minutes or so it was ready for use.
I did the same when I replaced master and slave cylinder on my current truck. This idea still works. Just my 2 cents take it as you will.

[nutz]

i normally bench bleed the master
the main thing to consider when bleeding anything is the air will get trapped in the highest spot in the system
so if your master angles down at all or your bleeder screw isn't at the top air will always be trapped
now the first thing i do is try and get the air moving in one direction
open the bleeder as someone pushes on the peddle (can use a stick against the wheel or seat )
when down i close the bleeder,do this a few times till fluid comes out
pump it many times then when down crack the bleeder ,repeat...
the clutch will self bleed somewhat .....cause the master is the highest point

[PwrWgnDrvr]

The reason for having to pull the pedal up is the monster "over-center spring" on the pedal arm up under the dash. Its purpose is to assist with pedal force when actuating the clutch. Sort of a quasi power assist system. When the bleeder is open, there is no counter force against that spring from the clutch pressure plate or return spring. On the pedal return, when it passes center, the spring pushes the pedal all the way up to release all pressure on the master/slave/throwout bearing.