Some months ago I had my 1983 F250HD with diesel & manual trans out for a spin.
The clutch had been feeling stiffer and stiffer, sometimes the gears would grind when I shifted, at other times normal action.
Suddenly the clutch went to the floor as I came to a stop, I was able to pull the shift level back to disengage the transmission.
I was able to pull the clutch pedal off the floor & get a little clutch action, enough to limp back home.
Clutch pedal went up a bit on the way home & I backed the truck into my drive. It has been there for months.
I read up on oil-canning of the firewall, made a video of it on YouTube. The sheet metal movement seemed like very little to account for this.
I disassembled the clutch pedal & rod mechanism, no unusual wear or binding. No firewall cracks. Removed the clutch master cylinder, fluid levels seemed normal, no leakage found. The hydraulic line was translucent plastic, fluid was clear.
Slave cylinder looked OK. I video'd the action of the slave when I got the clutch reassembled, it seemed OK.
I bought Ford's small firewall reinforcement metal plate E3TZ-7K509-A, but have not gotten around to installing it. The holes that need to be drilled in the firewall & the hump over the transmission look rather difficult to place for a person of my size & skill level.
The clutch now feels normal, so I took the truck out for a spin.
Clutch stiffness seems like new, action of shifting is normal, all is well.
I really did very little, just disconnected & reconnected the pedal linkage, dismounted the clutch master cylinder, jiggled it a bit & remounted.
Would appreciate any ideas about what happened. Never had such an apparently severe malfunction like this, suddenly get better for no reason.

 

Wierd. When you say you "dissasembled the clutch pedal and rod mechanism", do you mean you dissasembled the entire horizontal clutch pedal cross-shaft mechanism, or do you mean you removed the clutch master cylinder pushrod from the cross shaft pivot arm (the spot where a single spring clip holds the pushrod to the pivot arm)?

If the former, then perhaps there was binding somewhere in the horizontal cross shaft, and you freed that up by dissasembling/reassembling. If the latter, then perhaps the binding is intermittent and may occur again. It sounds like the hydraulic portion of the system is functioning properly.

 

I can't offer any genius advise, but I'll suggest that you install your repair panel BEFORE you need it. I wish I had, I might not have needed the larger repair panel.

Happy wrenching and good luck.

 

It was the latter. I just disconnected the pushrod from the pivot arm so that I could dismount the clutch master cylinder from the firewall.
The only thing keeping me from installing the reinforcement plate are the 2 holes I am supposed to drill sideways into the transmission hump - I don't see the room for even a right-angle drillhead to bite, unless everything in the front of the cab is removed first. The other holes that need to be drilled are straight through the firewall & seem easy to do.

 

I found that the lower of the two transmission hump holes can be drilled or "ground through" using a dremel-type moto-tool. The upper could be drilled from the outside (engine compartment) after installing the plat if one knows the exact distance between the lower hole and upper hole.

But the directions say the two side bolts aren't necessary unless cracking extends to the transmission hump. I only installed the lower of the two transmission hump bolts.

If you get a chance, could you measure the distance (center to center) between the two transmission hump holes on your repair plate? I forgot to do it before installation and now its kind of difficult to measure.

It's pretty tight in there, here is a link to a thread discussing this problem, it is just one of several:

https://www.ford-trucks.com/forums/1...ex-repair.html

 

Dang it, it just happened again.
I was driving in rush hour city traffic when the clutch pedal went to the floor as I came to a stop light. I was able to pull the transmission to disengage it without incident.
I could 'pop' the clutch up to a slightly depressed position - could feel some kind of resistance that wasn't normal. The clutch hydraulic action did not fully work the slave - it was hard to get back in gear, but I succeeded.
Thanks heavens for the granny gear.
I drove my last 0.7 miles home in 1st gear, varying in speed from 2 mph to 7 mph, fortunately all the lights were with me.
It seemed like 100 vehicles passed me. I was even able to change to the left lane and make a very slow left turn through the last traffic light and ease on into my driveway - I turned off the key instead of fighting the clutch, and the truck stopped sooner than the old clutch/brake method would have done.
I wouldn't be surprised if it was all back to normal this morning, which has happened before.

 

Hate to say it, but it sounds like either the master or slave are about to bite the bullet. If they have never been replaced, then you've gotten great service from them.
Ford did not make it easy to flush the fluid from this setup, and that little trick can greatly extend the life of these parts. It's also not easy to bleed the air out after replacing one or both of these.

 

I've had to replace the master and slave cylinder in my truck after I put the new clutch in. The easiest way I found to bleed the system is to push the pedal to the floor, use a stick to hold it in place. Open the bleed valve on the slave and let it gravity feed. The one thing you don't ever want to do is pump the pedal. For some reason this doesn't work like bleeding brakes. I still have to push the pedal quite a way to get it to engage but it works.

 

This whole clutch hydraulic system was replaced about 80,000 miles ago. The original problem was the exact same symptom as I have been experiencing with the exception that the 1st time around, the clutch hydraulics went out and never came back. At the time of the 1st replacement, Ford sold a complete clutch hydraulic system that was pre-filled with fluid and pre-bled. All the mech had to do was unfasten or unsnap the old system and install the new one and you were good to go.
Now the only parts I can find are all separate components: master, tubing and slave cylinders.

 

Good tip, I have been reading about the issue of bleeding the clutch hydraulics and this suggestion of yours is a new one, certainly worth a try.

 

Yup. That's what I had to buy as well. There was a good tip in these forums or somewhere else about bench bleeding the cylinders. something about pre-filling the slave cylinder and making sure the tube has fluid as well. Minimizes the air in the system. You should have enough room to get the slave cylinder down by the transmission even assembled. I would go that route if I were you. My tip is when the cylinders are already installed and you have to replace the tube because it was resting against the exhaust manifold and gave out while going down the street. This happened to a friend of mine. Not me. I would never do something that dumb...

 

I was curious about this and looked up such a thing in the parts catalog....

Yes, these kits existed! They included the master & slave cylinders, the hose in between as well as the attaching parts.

Most were for vans, they didn't officially offer these for pickups until 1988 (there are 9 kits total).

My guess is that some mechanic at a local dealer figured out the kit intended for a van would work, perhaps by using an original mounting bracket, or shortening the new hydraulic line, or something like that.



I nevertheless went searching for some of these kits but couldn't find any anywhere.

You might ping NumberDummy and ask him to take a look at this thread...I don't have an OSI manual (but he does) so I don't know but it's possible the part numbers have been superseded and we need to be searching for a different part number for the kit.

E8TZ-7A542-B KIT (CLUTCH MASTER CYLINDER) Includes 7A543 master cylinder, 7A512 hydraulic tube, 7A564 slave cylinder, all attaching parts.
Fits 1988/ F250/450 with 7.3L & 7.5L diesel engines, any transmission

D8UZ-7A542-A Hydraulic clutch conversion kit - Fits 1980/83 E100/350 vans

There are several others, too. Sec 71 Pg 13

 

FYI, my sure fire method of bleeding clutches on this system is on the forum somewhere.

With the entire assembly off the car, start with M/C with line attached.

Put slave side of line in jar of fluid.

Line side of master slightly up, SLOWLY actuate the master cylinder. Bubbles will come out into the jar. Keep going until no bubbles go into jar, make sure to top off master cylinder every so often.

Fill the slave cylinder with fluid. Make sure it's filled to the brim, as this will speed up the next step. Hook line into slave. With a helper watching the master cylinder, actuate the slave pushrod by driving it into the ground (push entire assembly into ground, SLOWLY, then slowly retract it). Doing any of this stuff fast will risk blowing all the fluid out of the master. Keep repeating this until the helper no longer sees bubbles going into the master cylinder reservoir.

Cap the master, hook it up to the vehicle.

Assuming your firewall has no flex, it should be ready to drive! Mine was, worked perfectly on the first try.

I hate to sound like a TV guru, but this method WORKS, and I tried EVERYTHING.

 

How is the line supposed to connect to the master cylinder?
My existing setup was all one piece from the factory.
I bought a replacement clutch master cylinder, all it has is the cylinder, an adjustable pushrod, a plastic ring, and a slotted pin, about 5/8" long, 1/8" diameter, slot running lengthwise.

 

Your original master cylinder should have that same roll pin, it goes through the snout of the M/C horizontally and needs to be driven out with a hammer and something of just slightly smaller diameter. (once you have it out far enough, it should be able to get pulled out with a pair of pliers)