Bleeding zf5 hydraulics?

[Hagan]

Hey guys,

Does anyone have any special tips or tricks on bleeding the master/slave cylinder? My clutch pedal feels like normal but I'm only seeing about 3/8" travel at the clutch fork and I can barely get it into gear without grinding. It engages at the very bottom of the pedal. There isn't any play in the pedals and the firewall doesnt appear to be flexing. It used to be an automatic truck.

I just can't get enough travel for my clutch to release.

 

[Randy Bush]

I hear they are a pain to bleed. Think a lot of guys buy the pre-bleed unit. Can't remember if a bleeder screw if there is with some one in the cab push down on the pedal while the bleeder is open and close bleeder before reaching the bottom. It can't be bleed like you do brakes , will never get all the air out.

 

[Va_Mike]

I just did this on my ZF5 today and it worked perfectly. Follow the instructions for bleeding in the truck. https://www.dieselhub.com/maintenance/zf-master-slave.html

 

[IDIBRONCO]

I hear they are a pain to bleed.

This is an understatement. I've never had any good luck with using the bleeder screw no matter what method we would try. The only way that I could get it bled was to just keep pumping the pedal. Both legs and my right arm would be sore by the time the clutch would work normally. Maybe the gravity method mentioned in the link would work, but I haven't tried it.

 

[Hagan]

I hear they are a pain to bleed. Think a lot of guys buy the pre-bleed unit. Can't remember if a bleeder screw if there is with some one in the cab push down on the pedal while the bleeder is open and close bleeder before reaching the bottom. It can't be bleed like you do brakes , will never get all the air out.

I cant find a prebled unit unless a 92-96 one would fit the older body style 87-91?

I just did this on my ZF5 today and it worked perfectly. Follow the instructions for bleeding in the truck. https://www.dieselhub.com/maintenance/zf-master-slave.html

I tried that method but already cut the strap off that holds the slave cylinder rod in. When I pushed the rod in it spilled brake fluid out of the master. I tried another method where I removed the slave cylinder and tried bleeding it.

This is an understatement. I've never had any good luck with using the bleeder screw no matter what method we would try. The only way that I could get it bled was to just keep pumping the pedal. Both legs and my right arm would be sore by the time the clutch would work normally. Maybe the gravity method mentioned in the link would work, but I haven't tried it.

That's how I've done it before numerous times. I've never had good luck bleeding it using the bleeder either. I've pumped my pedal over a thousand times. I count to 50 on each leg and then switch legs. I've moved my truck and made the mistake of driving it to work. It got worse and I was grinding gears on the way home.

I'm just not sure what's going on. I went with a South Bend clutch. I'm not sure if I somehow screwed up installing it or maybe it takes more pressure than the hydraulics can handle. Or maybe I got a bad master or slave cylinder.

 

[1mouse3]

My truck has the same hydraulics for clutch and it bleed easy, just some time is needed to get the bleed started. Before I started since dry was was to open the bleeder and wait for it to start dripping out, it took mine two hours. Now on to bleeding the system and a pipe would be handy if a helper is not available. First is with bleader open 3 times, I would push the pedal down and put pipe between seat and pedal. Then was on to last step 3 times where got a good pedal, was to pump up the clutch and do the same with pipe so can open bleader.

 

[bilbo]

Maybe it's a Ford thing, my Ranger was a major pain to bleed when I swapped transmissions. That slave cylinder has a bleed fitting like a brake caliper, so what I ended up doing was running a hose from there to a point above the MC. I then pinned the clutch pedal down with a chunk of wood as far and hard as I could get it to go, and used a vacuum pump to pull fluid from the reservoir through the slave and up to the catch can on the vacuum pump. Prior to that I had been fighting with it for about 6 hours. That got it to a point where I could at least move and drive the truck. I think there was still a slight bit of air in the system at that point but it worked its way out through normal use.

I don't remember from when I did my ZF5 clutch if there's a bleed fitting like that on the slave.

 

[Va_Mike]

I tried bleeding it the normal way first and it did nothing. Pump pedal have some one hold it and bleed the line.

The pedal never got any better. I then used the 1,2,3 method they talk about in the link. Have someone press the pedal and call out 1 that's when you open the bleed screw. They pedal presser will call out 2 when they have the pedal halfway down and the end 3 when the paddle stops. What I find worked best for me was to open the bleed screw on 1 and close it shortly after the pedal presser called out 2. That kept the system from pulling more air back in at the end of the pedal stroke. I never removed the unit or tried the gravity bleed.

 

[ih8minimumwage]

Also try adjust your pedal linkage out. Just swapped mine to a ZF from 4spd reusing the hydraulics and couldn't get the clutch to release. Tried all the bleeding tricks, but still no luck. Adjusted the linkage out a couple turns and works great now.

 

[Hagan]

Well looks like I got it figured out. I gravity bled it for a little while then manually pushed the slave back in multiple times. After I was done with that I used an old clutch master cylinder cap and drilled a hole in the top. I shoved in a rubber fitting that came with my Mityvac and pulled a vacuum on the system for 10 minutes. It works great now.

 

[Va_Mike]

Awesome. Glad to hear that you got it working properly.

 

[Mountainman]

I converted my 1990 E350 7.3 4x4 Van from E40d to ZF5. Bleeding is much easier if you do it on the bench. Fill reservoir, open bleed screw unitil hydraulic fluid drains out of slave cylinder. Close bleed screw. Then keeping reservoir full, hold master cylinder firmly and push rod in against wooden 2x4 bench. Keep doing this until its firm...doesn't take that long. Replace.

Now what I Think may be happening to you...is that linkage is not adjusted properly. Mine would engage almost not quite when all the way to the floor. On brake/clutch pedal you may have to adjust swing arm...which means you probably have to take pedal bracket out of truck if its like mine. The swing arm that master cylinder rod attaches to is splined. Pound it out carefully with hammer and rotate (Carefully contact splines to match) and hit it with hammer carefully tapping it in place. Reattach rod and it should give you more throw and engage...worked for me.

Recommend going to Dieselhub.com...they have bleed procedures and DO THE Clutch pedal bushing replacement at same time...its on their website....mine works great now