Hi, Guys! I need a little diagnosis help. I used the search function here and couldn't find what I needed to know, so I'm posting...

Here's the scenario: 1991 F-250 4X4 w/ a 5.0 and 5spd manual. When I bought the truck a few months ago, I knew the truck didn't seem to have much clutch left but it was doing OK for around town stuff.

Went out to use it last week and saw the clutch pedal was about halfway down. I pushed down on the pedal and there was SOME resistance, but I knew something wasn't right.
I started the truck and went to put it in gear and all it would do is grind. I could turn off the engine, put it in gear and then bump start it and take off, but, hey, that's no good.
Soooo, since I'm an old dude who hasn't worked on anything this new in quite awhile, I don't where to go from here.
I know my truck has the hydraulic clutch system which includes the clutch master cylinder, the fluid line, and in my case the internal hydraulic throwout bearing.
I pumped the clutch numerous times and the level in the clutch master didn't seem to go down which would indicate that there wasn't a leak in the line, right? From there, I got nothin'...
Understand, I'd love to just drop the trans/t-case, etc., and just do a new clutch, but I was hoping it might be something simple like the clutch master just so I can get it moving around town a bit until my financial situation is better to do the whole shebang correctly.
Anyone have a clue as to how to diagnose whether it's the clutch master, hydraulic t/o bearing, or did the clutch just give up, just like that? For the record, when I pulled it into the driveway last week, it was shifting and operating just fine.
Can someone give an old dude a hand?
Thanx!

 

Any signs of a fluid leak in the bell housing area
which would indicate the slave cylinder is leaking?

The system is easy to bleed.

Remove the clutch master cylinder cap and remove
the black rubber bladder/diaphragm.
.
Make sure the fluid is topped off as you bleed the
system.

Put the clutch master cylinder cap back on.
Pump the clutch pedal a dozen times.
Use a piece of wood and wedge it against the clutch
pedal and the front seat to keep the pedal to the floor.

Go under the truck and crack the bleeder valve open.
A strong stream of brake fluid should shoot out.

If air is in the system the fluid will spit out which
will be obvious and indicates there is a leak.

Close the bleeder valve and repeat the process until no air is in the system.

If you can't eliminate the air, either the clutch
master or the slave is bad. Since you say
the fluid in the master doesn't change when
the clutch pedal is engaged the clutch master
is probably the problem.

The system uses DOT 3 brake fluid so don't get
the fluid on any painted surface.

At the clutch master cylinder, the hose is held on
by a roll pin that you press out. The hose will then
pull off. At the clutch slave, to remove the hose you
press the plastic bushing inward which releases some
metal springy fingers and allows the hose to be pulled off.

Also have someone engage and disengage the clutch pedal.
Look under the hood at the clutch master cylinder and verify it's not pulling
away from the firewall. A very common problem is the
plate that the clutch master cylinder is mounted to pulls
away from the firewall.

Worn clutch pedal pivot bushing or a cracked clutch pedal
mounting bracket can also cause clutch pedal problems.

Inside the cab, look at the rod from the clutch master cylinder where
it attaches to the clutch pedal. Verify the plastic bushing is in good shape.

 

Thanx, F150XLT. I didn't see any obvious signs that the slave t/o might be leaking, but I'll take a closer look. Sometimes it's nice to have a truck w/ a 4" lift so you can get under the truck so easily... :-)
Anywho, your outline for checking the master sounds like the place to start. I'll take a whack at it over the weekend if I can and update here when I can (lots of overtime right now at work, so I'm suckin' it up...)
Thanks!

 

Hydraulic Clutch Troubleshooting .: Articles Also click on this link and check it out and also check the firewall around the master cyl for cracking/flexing.

 

UPDATE: First, a quick recap... Clutch was working OK one day. The next time I went to drive it, the clutch pedal was halfway to the floor and I couldn't put the trans in gear when I pressed on the clutch pedal.

First, I pulled the rubber inspection cover and had my friend pump the clutch a few times. I noted that the T/O was pushing on the pressure plate to some extent, but I don't know how far it needs to go to fully disengage the clutch so I can put it in gear. (Note: At this point, the clutch pedal was still in the same halfway to the floor position as when this problem first came up...)

Then, per F150XLT's instructions (Thanks!!), I had my friend pump the the clutch a dozen or so times and hold it in while I cracked the bleeder. A pretty good stream came out and I shut it back up. There didn't seem to be air in the lines. The clutch pedal, however, was now even further towards the floor than it was before.

I also checked and made sure that when the pedal was pumped that the clutch master cylinder wasn't moving away from the wall as was mentioned as a potential problem.

I poked my head under the dash and, admittedly, I couldn't manage to see everything that was mentioned and check all that stuff (as I was a bit pressed for time), but it did look like the bushing was fine, and it didn't look like anything else was broken or pulling away from the firewall, etc.

Sooo... with the info given (maybe too much?...), anyone have an idea of what's wrong, or why the pedal would go even further towards the floor (and stay there) when I popped the bleeder to check for air in the lines, etc.? Sorry, but I'm an old dude and just not used to how all this newer hydraulic clutch/TO bearing stuff works. If this was a truck with an exterior slave on the bellhousing it'd probably be easier to figure out what's wrong, but...

Annnd, I'm checking the link that Lazy K suggested as we speak...

Thanks in advance,
Chris

 

look up under the dash with a light. follow the clutch pedal, and find where the master cylinder pushrod attaches to the pedal. there should be a bushing in there. it sounds like the bushing fell out, giving you slop in the pedal/rod connection.

 

UPDATE #2:
Checked the push rod bushing and it appears OK. Didn't see any obvious signs of the bracket being cracked, etc. I undid the pushrod and was hoping it was adjustable and tried to screw it out, but to no avail. I couldn't see the entire pushrod since there's some kind of plastic dealie-bobber with some wires connected to it covering the rest of the pushrod at the firewall. I don't know what the heck that is, or HOW that comes off. I took a pic, but don't seem to be able to upload it here for your perusal.

At this point, I guess I'll just buy a new clutch master and start replacing parts and hope for the best. I'm sure there's a step by step for the complete idiot somewhere here, sooo...
But if anybody else has any other input, just let 'er rip.
Thanks again to F150XLT for the extensive info...good stuff

Thanks,
Chris

 

Just wanted to close out the thread here...
Looks like the clutch master was toast. It appears the piston was sticking in the cylinder.
Went to replace the master and all's good.
Thanks for all the great responses.