Hydraulic clutch problem

[iamtherealJayy]

1987 Chevrolet V20, I’m still having slave problems. I can’t keep pressure in the clutch pedal. My current problem is the fluid is getting warm and got really dark so tomorrow after work I’m going to drain it and flush it with new fluid. The pedal feels hard to an extent, but it grabs at the top(I prefer hydraulic to start grabbing as soon as you start letting off the pedal) I don’t grind going into gear but I’ve replaced the slave twice, master once, and the line between them once. I’ve bled it twice now within last couple months by unbolting it from the trans and taking reservoir cap off and pushing the slave rod in and releasing and kept doing it until it got harder and harder to press, putting reservoir cap back on and rebolting the slave. I gain a little pedal but not much. I don’t think the reservoir helps any since it won’t hold any extra fluid with the rubber cup you put in it.

 

[fast 99]

How old is the clutch? Have seen a TO bearing get so tight [dirt/dust] it can't slide causing a hard pedal and if bad enough can causing a slave cylinder pushrod to bend. Front bearing retainers with too much wear can contribute.

 

[iamtherealJayy]

Clutch is almost 2 years old, around 4000 miles so far. From previous owners apparently this truck has always eaten slave cylinders. If I constantly drive it everyday the pedal isn’t as noticeable but if I don’t drive it a week it becomes almost undriveable

 

[iamtherealJayy]

Alright recently just got my custom license plate and plan on doing some work to this truck to make it driveable again. I’ve bled in the slave several times and the fluid is dark. What could be causing the fluid to get dark? Heat? From? I plan on completely flushing out all the dark fluid today and getting the pedal feeling nice. Where should a hydraulic clutch start grabbing? When I first did the slave in the truck it started to catch as soon as I lifted up the pedal and it felt solid. After a clutch replacement(pressure plate Grenaded) I had to bleed the system again because I lost all pedal travel and it all engaged at the top absolute misery drive home. The truck has never acted right since in my opinion. So am I having the wrong opinion on this and it’s acting completely fine? Was it wrong in the beginning but the blown clutch was all I knew so I think it’s right? I’m a fairly tall person and with the seat all the way in the bed I can still press the pedal to the floor so I really have to lift my leg up when it wants to grab at the top.
One last question, the reservoir.. is the cap supposed to have a rubber cup that pushes every single drop of fluid out of the reservoir? I absolutely hate brake fluid and there’s no way of putting the cap back on without getting fluid everywhere. I would also assume you’d want a little extra fluid in the reservoir but I really don’t know.

 

[iamtherealJayy]

Just spent ~2 hours flushing and bleeding the slave. It has plenty of pressure and I had plenty of hopes. After I got clean fluid coming through the bleeder I closed bleeder unbolted slave held it angled so bleeder wasn’t highest point and pressed the rod in atleast 50 times until I got 5 pushes in a row that didn’t make bubbles in reservoir. My arms burn. I started the truck put it in low and let off. Pedal went something like nothing nothing nothing is there even anything here? Nothing nothing whammy truck stalled(parking brake on) why in the actual hell is my clutch worse now than when I started? It grabbed mid ish now it’s completely at the top again.

 

[fast 99]

Have had issues bleeding those systems by the usual method. What I have found, and it seems illogical, bleed them backwards. Suck the fluid from the master. Open the bleeder on the slave and with a NEW pump oil can and a section of hose push it on the bleeder. Pump fluid in until it fills the master. Close the bleeder before taking the hose off. May take a couple times but it works provided there aren't any other problems.

Don't understand the reason for those odd caps but just remove enough fluid to install it. There will still be some fluid in the master.

 

[iamtherealJayy]

So many questions. Do I pump the fluid in with the slave attached or removed from bell housing? I’ve already replaced the master once, line between once, and slave twice. The slave rod pushes out when looking under the truck so I would think it’s got plenty of pressure but the pedal doesn’t do anything until the very top. Should it engage at the very bottom? It did the very first time I did it so that’s what feels best to me so my knee isn’t touching the roof to let off the pedal

 

[fast 99]

Hyd clutches feel very similar to a regular linkage clutch. The only operational difference is they are self-adjusting and the need to check fluid level.

I have been in your shoes these can be very frustrating.

Hook everything up and pump fluid in from the slave. Doing it this way will work.

 

[Ricko1966]

I know,late to the party again,but I get reading some of these old posts when I have some spare time. What I've done on hard to bleed hydraulic clutches before is put a piece of tubing I've got clear but don't see vacuum hose wouldn't work. Anyways put a combination wrench on the slave bleeder then the tubing hook the other end of the tubing to manifold vacuum and start your vehicle now go Crack the bleeder. Watch your reservoir so you don't suck it dry. Works awesome.

 

[85 Fleetside]

My 85 C10 factory manual says to let the slave cylinder hang with the bleeder up and gravity bleed. I have replaced my slave cylinder four times over the past 30 years and this method works well. Just keep adding brake fluid to the master cylinder reservoir until the fluid runs clear. FWIW, after reconnecting the slave cylinder, my clutch pedal ends up with about one inch free play.

 

[bucket]

I know,late to the party again,but I get reading some of these old posts when I have some spare time. What I've done on hard to bleed hydraulic clutches before is put a piece of tubing I've got clear but don't see vacuum hose wouldn't work. Anyways put a combination wrench on the slave bleeder then the tubing hook the other end of the tubing to manifold vacuum and start your vehicle now go Crack the bleeder. Watch your reservoir so you don't suck it dry. Works awesome.

That's a nifty idea! Like a high-performance vacuum bleeder.