TheMitch

Hi folks,

An odd thing happened on my way home from an out-of-town trip this weekend. Fortunately it happened a mile from home, so I was able to limp the car home.

The clutch on my 1992 LT1 6-speed started acting really odd. At the last couple of stoplights, the clutch pedal felt very loose, and would only disengage the clutch the last 2-3 inches of travel. In the last couple of blocks before my house, it wouldn't disengage at all (despite putting the pedal on the floor) unless I pumped it a couple of times. Just getting it into the garage was an adrenaline-inducing exercise, in which I stalled it twice and actually had to force it out of gear before nearly crashing into the wall because the clutch wouldn't disengage.

Although I'm handy, I'm no clutch expert. It feels like either a linkage or hydraulics issue (assuming the clutch is hydraulically assisted - I have to confess ignorance here). I've thumbed through my FSM but haven't found a clear troubleshooting path.

Has anyone any experience with or knowledge about this type of problem? If so, your input would be appreciated.

Thanks,
Tim

John A. Marker

Sounds like it might be the clutch slave cylinder.

lt4obsesses

First step is to check fluid level. It is under the ECM on the driver's side. To remove the ECM it's a 7mm socket and two screws.

If it's low, and sounds like it should be, then check at the bottom of the bell housing for signs of fluid, this is where the slave leak collects.

If not there, check the floorboard under the clutch pedal. This would be the clutch master leaking. Of course check the lines and connections in between.

ricasso

Lack of fluid is your problem..

Tom400CFI

TheMitch

Awesome - thanks so much for the quick advice. Hopefully just a fluid issue.

Tom400CFI

After you put in the fluid, tap the pedal a few times (10 or so?) to burp the air you've gotten into the system, back out through the reservoir. Once a normal pedal returns, you might want to go looking for the leak. Hint: inside firewall (leaking master) or out of the slave, under the car.

TheMitch

First of all, thanks for all the tips.

Unfortunately, after checking the fluid level (it was full) and replacing the slave cylinder, I seem to have the same problem. It works a little more consistently now, but if I press the pedal very, very slowly, or leave it depressed for a while, the clutch won't disengage. Checked the fluid levels again and it's still completely full. There are no signs of leakage at all.

I'm stuck. Could this be the master cylinder? That seems to be a fairly simple device which either works without leakage, or leaks and eventually doesn't work. I don't know what else it might be.

Any further advice is appreciated.

Thanks,
Tim

antfarmer2

New master now fluid is leaking by internaly

Dalesc4

Could have a collapsed clutch pressure plate
Will do the same as no fluid
So if u have fluid and u can see it pumping
Then it's the clutch so gearbox out
Sorry

SJW

If the clutch will disengage normally when you actuate the pedal quickly, but won't disengage if you take the pedal to the floor slowly or take it down and hold it there for a while, you very likely need a new clutch master cylinder.

What's happening in this scenario is that the piston seal in the master is failing and allowing fluid to sneak past, thus bleeding off fluid from the pressurized side while the pedal is down or on its way down. This reduces the travel of the clutch fork such that the pressure plate won't travel far enough to fully release the clutch disc.

Brake master cylinders can fail in the same way, with the symptoms being either a slow fade of the pedal toward the floor (this typically first shows up under very light pedal pressure), or an outright failure where the pedal drops straight to the floor when stepped on, in a case of extreme failure.

Live well,

SJW

TheMitch

Thanks SJW. That makes sense, and would explain the clues I'm finding.

94corvetteC4

I had a similar issue the other day. I was sitting in the drive through waiting on my food for the first time in my 94 since I got it. I was on level ground so I had the clutch in and in 1st gear with my foot off the brake. All of a sudden the car jumped forward and died. I couldn't get it out of 1st gear so I let the clutch pedal up and pushed it back down and took the trans out of 1st gear and re started the car. I put it back into 1st gear and got my food and left. It hasn't happened since but I then again I haven't sat that long with the clutch in since then either. I'm going to see if I can duplicate it again in my driveway. If it does it again then I'm thinking either air in the clutch system or I'm losing pressure in the system. I have no leaks.

AgentEran

I think SJW is hitting on the head.

I literally just had the exact same thing happening to my 93. My car was acting the exact same way. I change the oil in the ZF, didnt help.. Bleed the system.. didnt work.

I finally replaced the slave and it got better but there was still an issue in the master that would cause the pressure to leak past the piston seal. I replaced the master and haven't had an issue since.

I strongly suggest you replace your master next.. Its recommended you change them at the same time anyway.

Christi@n

Master and slave need to be replaced at the same time as a couple, you could try to drain system and add fresh fluid, if not already done

Christi@n

Master and slave need to be replaced at the same time as a couple

Rattenni

I would only recommend playing the no-clutch shift game in an emergency and to not do this unless required. I used to play this game every now and then on my Ram pickup and the transmission ended it’s life early. In a pinch OK...

AgentEran

Whoa! raise a threat from the dead ever?