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Clutch won't bleed

16K views 6 replies 3 participants last post by  vegoildieselguy 
#1 ·
So had to put on a new slave cylinder and got it on and it is hanging so we can bleed it. I filled up the master cylinder hoping for the fluid to gravity bleed down the line into the slave cylinder, well it didn't and it won't no matter what type of pumping or series of steps I do, had two guys working on it so I have enough help it, the fluid just won't go down. So what is the deal if the fluid won't even go down to the slave cylinder?
 
#2 ·
You have to fill the slave cylinder before installing it. It's a fun little job, hold the cylinder at an angle and dribble brake fluid in the line port till it's full. Then tap the cylinder to dislodge any air, and repeat many times. When you're certain it's full, tap it again and a big air bubble that's been sitting in there since you started will come out and you can keep filling & tapping.

Once the slave cylinder is full, put a pan under the hose and fill the master cylinder. Allow fluid to drain out of the hose until a solid stream with no bubbles is coming out. Fill the master to the top, quickly get under the truck with the slave cylinder, the roll pin for the line, and a small hammer. Insert the line in the port and install the roll pin.

Now for the most fun part of all. Clip the bracket halfway onto the mounting ear, and using some kind of pliers grasp the pushrod and force it into the slave cylinder until you can slip the pushrod into the pocket in the release fork. Then seat the slave cylinder fully on its mounting ear, and try your clutch. If it doesn't grind going into reverse at idle you're good. You may have a small amount of air in the system, that should bleed out with normal use.
 
#3 ·
When I replaced the clutch slave cylinder the part store had quarts of brake fluid on buy one get one free. I thought man that is more than a lifetime supply, until I used a quart and a half getting the system bled. What a mess!

Much later I found a ford issued TSB on the neat and easy way to bled the slave cylinder.
I usually have the front of the truck up on ramps to give me more room under the truck and it seems to help having the nose up, then with someone watching the fluid level in the clutch master cylinder, push the clutch-fork toward the front of the truck pushing the rod slowly into the slave and the slowly releasing. Repeat as needed.

Here are the steps from the TSB:
1. Remove the master cylinder reservoir cap and diaphragm.
2. Check the fluid level to be sure it is at the step diameter of the reservoir. Do not over fill.
3. From below the truck, push the release lever slowly towards the front of the truck several times. Figures 11 & 12.
4. If it will not move, the master cylinder pushrod is not set correctly. See repair Step # 19.
5. Check the fluid level and replace the diaphragm and cap.

I have used this on my truck a couple of times and it not only works well, but is easy and clean.
 
#4 ·
That's how I used to bleed my GMs, get everything hooked up with a full reservoir then crawl underneath and work the release fork back and forth a dozen or so times. I tried it when I first lost my F350 clutch pedal but it didn't work. I didn't have the front end lifted, though.
 
#5 ·
I get the jist on how to bleed the slave cylinder but my master cylinder isn't sending any fluid down to it, my master won't let fluid gravity drain down through the hose at all, the slave cylinder is off the hose. I tried all types of things but it seems that there is a big air pocket in the master cylinder or something. I tried the reverse bleeding method using an oiler can and all that did was build up pressure in the clutch line but didn't allow any into the master cylinder. I expected it to overflow the master cylinder by doing this if it worked out right but it did not. While doing this the clutch pedal was up. Is there a check valve or something in the master cylinder perhaps?
 
#6 ·
If the clutch master cylinder push-rod is too long or mis-adjusted fluid can't flow back into the master cylinder. Try disconnecting the push-rod from the clutch pedal. That is what step 4 is talking about.
 
#7 ·
The master cylinder was shot (the original from 85). I disconnected it and it came completely out of the master so I replaced it and all is well. Now for timing this old thing cause it won't start by itself and smokes like a some beach. :)
 
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