87GMC

I did a search and didn't find any threads on this exact problem.

My clutch peddle loses pressure when you keep it down for a few secs. As long as your not on it the pressure keeps clutch peddle up. If you keep it down for a bit it stays on the floor and you have to pull it back up push it back in and pull back up to build pressure, almost like pumping. I figured maybe the slave is losing pressure but i have no leaks anywhere. Resivor is full of oil and looks good never goes down so i know its not leaking anywhere. Clutch is not slipping and is grabbing just fine. I figured it has to do with hydros but dont know if it would be master or slave.

Could this also be caused by air in the system? What gives

DONAIMIAN

iTrader: (18)

You said it was "full of oil" is the fluid black? If so thats one of your problems. Flush the system.

87GMC

not real black looks greyish. Maybe a flush with a mitivac?

87GMC

anyone else with ideas?

steve-d

iTrader: (7)

Air in the system.

Have you disconnected the hydraulic system at any recent point?

If the components are good, you need to:

** suck out old hydraulic brake fluid in the clutch MC reservoir with a turkey baster;
** fill with good DOT 4 brake fluid;
** bleed the system.

Use mitey vac, OE bleeder or get a remote bleeder line if you have to remove the trans and replace the slave.

Steve

bbodyguy

It is your master. I have been dealing with this problem a few times now. The seal in the master piston is letting fluid slip by, and the pressure in the high side slowly bleeds out, and the clutch then begins to engage.
If you have the McLeod master, and look in the resivoire,and see little black flecks, that would be the seal getting chewed in the master.
That would be my educated guess.

87GMC

its all stock. 1998 with 72000 miles

I have never disconnected any lines or given it any reason to have air in the line.

I was kinda of thinking the master like you mention because if it was the slave it would be leaking.

BigJoeBob1

iTrader: (2)

I have heard that the slave either works or doesnt work at all. So it is probably a leaking master cylinder. Check you resevoir connection as well.

JasonWW

iTrader: (2)

This is very similar to what is happening to mine. In fact, when out of gear I can apply light pressure to the pedal and it will slowly go down to the floor over about a 15 second period. It seems just like a master cyl. seal letting the fluid go by.

It's not related to heat nor high RPM. Just ordinary driving around as well as randomly. Sometimes it shifts fine, sometimes it will not return all the way and that is usually followed by it staying on the floor. I have to pull the pedal up with my toe and pump it a few times to get it back to normal.

So I assume this particular problem is the master cyl. seal leaking?

ZoFastSS

iTrader: (5)

I'd still say air in the system.

JasonWW

iTrader: (2)

Why?
Air doesn't make sense.
The pedal is not soft or spongy.

JasonWW

iTrader: (2)

Well, it's doing it all the time now.

I'm off to get a master cylinder. Gonna do the drill mod on it before install.

JasonWW

iTrader: (2)

I haven't put the new parts on yet. I did cut a square hole in the floor so I can access the bleeder. God that makes it so easy! Anyway, no air in the system, just fluid. Made no change at all in pedal feel, so I'm going to change the MC out tomorrow.

fastsspr

iTrader: (49)

Mine do the same i installed a new zo6 slave and the problem persist.I have the macleod master with about 30k miles on it.This going to be my next.Move.

JasonWW

iTrader: (2)

I don't think it's been mentioned yet, but my new MC has a new design on the end of the hose. Doing the drill mod is now a bit different.

There is no longer a restriction about 1" inside the fitting, it now has a tiny hole right at the end. You need a drill bit a tiny bit smaller than 1/8. Just drill the end out.

Here is a size comparison:

JasonWW

iTrader: (2)

Got the new MC in. Problem solved.
Engagement point is a little higher, but that may change after a while. Goes into 2nd and 3rd more smoothly. The notchiness is gone.

87GMC

did you do and if so what trick did you use to get the u-bolt back in? I can seem to line mine up

Louie83

iTrader: (3)

Here is a thread with tons of people who had the same problem. Certain things fixed it for some people, while something totally different fixed it for others.

https://ls1tech.com/forums/manual-transmission/401266-clutch-sticking-floor-step-step-troubleshooting-hope-helps.html

JasonWW

iTrader: (2)

You almost have to have 2 people to line it up. One inside to hold the MC straight and the metal bracket just right and to also tell you when you are close to the hole. If you leave the reservoir loose you can slide your hand through that opening, on the outside of the power booster, and line up the upper, outer hole. It's tricky, but if you have someone inside to tell you to go up, down, etc... it can be done.

It is a crappy design, BTW. Thankfully you don't have to do it very often.

cobrakiller221

iTrader: (12)

I had this same problem with my 2001 t/a. I replaced the master cylinder with a $49 one from napa auto parts and mighty vac'd the system from the bottom and the top. PROBLEM SOLVED..