Intermittent clutch engagement, master, slave or mechanical?

[scotts90ranger]

Just got home from a ~1800 mile road trip in the '97 Ranger, couple issues came up... One was today when I was going through Redding CA, went up a hill and downshifted to 4th and had no clutch engagement... coasted down the shoulder with the flashers on for a bit, worked the clutch pedal some, dumped it in neutral a couple times then just tried 4th again and had some clutch so kept going... I'm used to the symptoms of if the clutch doesn't disengage, but this not engaging thing is odd... Oh, no vibrations so I'm assuming the friction disc springs and pressure plate fingers are intact.

The pedal feel is off, first inch feels normal then there's not much resistance. After the first time it came up I played it safe and drove for the next 100 miles shifting without the clutch (much slower, but it shifts fine if the shaft speeds are matched, no tach so from pure experience...), had to get gas so I tried it again at stop signs and such, it worked again. The problem seems to come when everything is hot climbing hills, it works sometimes then nothing, I smelled clutch once when I tried again on a big hill. If you are patient whatever is holding pressure bleeds off to where it will hold again.

My gut feeling is something in the slave cylinder is sticking when it's out somehow, but I'm hoping that isn't the case...

Any experience or bright ideas before I gear up to change everything in time I don't have?

 

[rusty ol ranger]

If you sit on level ground in 1st with your foot on the clutch...but not the brake....does it start to creep away?

Hows the fluid level?

 

[Curious Hound]

Almost sounds like there’s a lot of air in the slave and it’s heating up, expanding and disengaging the clutch. But I wouldn’t think it should get that hot. I’d try bleeding it.

 

[scotts90ranger]

Dustin, it's the other way around, when it's mad it won't engage, if you use the pedal it shifts like normal but sometimes you just don't get any clutch friction until either the slave relaxes or the blockage in the master releases.

Eric, I thought about that but if I understand things correctly the master cylinder should bypass pressure at rest if everything is working correctly. For that to happen there would have to be some foreign material blocking a port somewhere. Plus if there was air in the slave it wouldn't disengage, and if it was truly heat related pressure wise I would have lost the clutch driving around without using the hydraulics, everything goes south when you cycle the pedal and need to transmit most of the engines torque.

Not trying to shoot down ideas, I had 400 miles to think about what is going on, just don't remember reading about something like this in the past

 

[Curious Hound]

Hmmmm...

 

[scotts90ranger]

Precisely!

I guess I could just order and install master and cross my fingers... I hate to throw parts at things, but there's not much to that system, and for a daily driver it might as well all be fresh and start with the easy stuff...

 

[Shran]

Pull the inspection cover and have someone else push the pedal while you watch?

There is a YouTube video floating around that describes the bleeding process, and they mention having 0.060" of pressure plate lift off the clutch disc being the Ford spec for clutch disengagement.

 

[scotts90ranger]

I think I'll get a master cylinder tomorrow and attempt to put it in, but before I tear into it I think checking the slave cylinder operation is a good idea, daylight is leaving fast anymore so didn't have time tonight to screw with it...

 

[scotts90ranger]

Got a master cylinder, that was the culprit... That guy is kinda shoved up in there but not too bad... still easier on the '90 I think but it was nice only having one fastener... A slave will be needed when a clutch is due, I took off the inspection cover to look up in there and it's kinda damp and covered with clutch goo but it has great pedal feel now. Must have been some goo in the master, the fluid that came out of the hose was nice and clean though.