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Alternatives to bench bleeding the clutch master cylinder

Discussion in 'Stock 1991 - 1994 Explorers' started by Dubious_Downfall, November 4, 2019.

^^Searches ExplorerForum.com^^





  1. Dubious_Downfall

    Dubious_Downfall Member

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    My manual 93 Explorer 4x4 will grind a little when putting it into reverse at times. It can also become difficult to shift into reverse and first gear. It usually doesn't give me any problems after a cold start, though. Even after warming up the engine while parked. It usually seems to happen after a bit of driving. Even a very small amount of driving, sometimes. Like, the distance around a parking lot.

    I bought this truck less than two months ago from an estate representative. It was previously owned by an older gentleman. The representative didn't even remotely understand what they had. Upon inspection, the motor is definitely rebuilt. I can tell because the whole engine bay has been cleaned, the motor looks almost new aside from the rusty headers, and it runs smoother and with more power than any of the other three Ford 4.0L OHV motors I've driven. One of which was a backyard rebuilt motor.

    I bring up the rebuild because I'm almost positive that every single problem this truck has mechanically can be traced to the rebuild. Occasionally at idle, the temperature will jump, presumably from air in the coolant lines, which is common after a rebuild (Already taking care of this). The clutch problem I'm having is typical of air trapped in the clutch master cylinder, which tends to happen when clutch parts are replaced (Again, common during Explorer engine rebuilds). And the AC system needs to be recharged.

    So, to address my problem and my questions...
    The most common, and often considered the only complete way to bleed the clutch master cylinder in these trucks, is to remove the clutch lines and master cylinder from the truck and bench bleed the system. The reason for doing this is because Ford (in their infinite wisdom) installed the clutch master cylinder at a downward, front facing angle. This causes air to easily be trapped and be nearly impossible to remove without flipping the master cylinder so that the air pocket is at the top, which is usually done by removing the cylinder.

    So, my thinking and "question" is as follows: I need to tilt the clutch master cylinder. I don't want to remove it because... "Ain't nobody got time fo dat!". And frankly, it's just a huge pain in the butt.
    Can I lift up the front end of my truck enough to angle that master cylinder upward?
    I have options. It's got 4 wheel drive. I could find a big a** rock and climb it with the front wheels, chock the rears, then bleed it. I also live very close to a city which has roads so steep that calling them a 45 degree slope might not be an understatement. I can't help but wonder if parking it facing uphill on one of these roads might work. Deflating the rear tires might give an extra degree or two of angle. I just don't know how much angle I need before the cylinder is level.

    Does anyone know what the actual angle the master cylinder is installed at?

    Has anyone had success with this or similar bleeding methods?

    Is there an alternate way to get the air out of the master cylinder?
    I've seen a video where a guy removed the plunger from the master cylinder, let the fluid flow out, then stuffed the plunger back in as it flowed, which was done with the master cylinder still installed on the truck. Has anyone heard of or tried this?
    <-- The video I'm referring to.

    Is it possible that these symptoms are cause by a bad throw-out bearing/slave cylinder? (Seemingly no leaks)

    I'm open for suggestions. As well as any resources that anyone might deem useful for my predicament.
    Thank you in advance, guys! This forum is the only reason I'm able to keep these trucks alive long enough to become attached to them.

    This is unrelated, but because the previous owner clearly loved this truck... I'm naming it Noble. Noble is the previous owner's name, which I found on the old registration in the glove box. I'll never meet the man or know almost anything about him, but I know he was part of our family. And if I could, I'd personally thank him for keeping this gem alive.
     
    Last edited: November 4, 2019
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  3. 410Fortune

    410Fortune MUD SEASON 2.0 Staff Member Moderator

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    yes remove the top of the master cylinder and that will remove any air if trapped. That video is one of my favorites

    yes a tiny air bubble the size of a pin head can cause the clutch issue you are having

    But so can using a cheap slave cylinder when rebuilding the clutch

    Have you checked the slave cylinder for leaks? Any loss of hydraulic fluid from clutch reservoir?
     
  4. Dubious_Downfall

    Dubious_Downfall Member

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    If you say it's good, it's worth giving a shot, Fortune.

    Alright, then my "research" is paying off, since I'm actually making a proper diagnosis. It's worth mentioning that before posting, I tried and failed to bleed my clutch using the one-man bottle method (Ran the reservoir dry. I know... Rookie mistake.). I calmed my nerves, got my roommate to hold the pedal, drove the front wheels onto a curb for angle, and bled it the old fashioned way. It worked enough to get it back to the way it was before my blunder. But it didn't fix the original problem. So I made this thread.

    I changed my transmission fluid after I noticed the issues, and used the opportunity to check everything while it was dry. No leaks. Not one under the whole truck! *Knocks on wood* So I'm pursuing the bleeding as much as I can before resorting to dropping the transmission to check my slave cylinder. Since it's likely that quality parts were used, based on how the motor runs and the rest of the truck has been kept. But that's just a theory.

    Next step is to order lock-ring pliers so I can do this properly and add to my slowly growing tool collection.

    Just to clarify...
    All I have to do is remove the lock ring, pull out the piston/plunger enough for fluid to come out, then shove it quickly back in the cylinder, all before re-locking the lock ring?
    I don't need to remove the linkage that connects the master cylinder to the clutch pedal?

    Assuming that's all, I'm also going to two-man bleed it afterward, then let it gravity bleed for a good long time. Maybe 30 minutes to an hour. Just to be extra sure. Unless it's really solid right after the repair.
     
  5. 410Fortune

    410Fortune MUD SEASON 2.0 Staff Member Moderator

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    You got it

    Except skip the last part about gravity bleed and all that.
    After you remove the plunger and get fluid to the top of the master you are pretty much done with the hard part.

    It takes 3-4 bleeds on the slave cylinder screw to remove all air from the slave. The slave only holds about two tablespoons of fluid.
    Have your helper slowly press the clutch pedal 5 times and on the 5th time hold it to the floor, open the slave, let air /fluid out and close.... Repeat twice, maybe three times and the slave is bled. The air bubble that causes all the issues is at the top of the master cylinder, always. If there is ANY air left in the line or master cylinder it will find its way to that spot again. To fix, simply remove the plunger again.

    I used to spend about 45 minutes to an hour bleeding the clutch hydraulics. I would remove the master and the line from the truck, hang them on the wall and start bleeding. This involves using all your body force to depress the master cylinder plunger and wrap on the lines with a screwdriver to hopefully free up all the air bubbles. After 45 min of fighting it this way I would hope we got all the tiny air bubbles out and then install in the truck, and finally bleed the slave cylinder.

    Now I don't do any of that.
    I just fill the reservoir attach the line to the master, and then remove the plunger. All air is removed this way in about 30 seconds. Then I install in truck and bleed the slave
    Done.
    Takes 5 minutes, I wish I knew this trick 20 years ago....but that was before Youtube.
    I have FIXED 10+ trucks by getting that tiny air bubble out. New clutches, cannot get 1 or R = trapped air bubble
    When you remove the plunger and the fluid comes up to the top of the master cylinder you have just removed all air from the master and there is no need to bench bleed ever again!
     
    Last edited: November 4, 2019
  6. Dubious_Downfall

    Dubious_Downfall Member

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    Thank you so much, Fortune!

    Ordered my snap-ring pliers. They should be here today. I'll probably attack that lock ring before work tomorrow unless I get antsy and do it overnight. I'll let you know how it goes.

    If it works, which I expect it will, then this really needs to become more common knowledge. I have been researching this problem for over a month and only just last night stumbled upon that repair video. Now all of the stressing I did seems pointless, in hindsight.

    The process is so simple that I'm even considering doing my own shaky phone camera video, just to help get the word out.
     
  7. 410Fortune

    410Fortune MUD SEASON 2.0 Staff Member Moderator

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    I converted my bronco II from a 5 speed to an automatic because when I converted to 4.0 we used new clutch
    it was never right
    3 different clutch attempts, 2 different 5 speeds and finally I gave up and went auto, better for 4x4ing and stop and go traffic
    Years later I would learn about this trick. The air bubble......
     
  8. Dubious_Downfall

    Dubious_Downfall Member

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    I could kiss you, Fortune! My clutch pedal feels SO much better. And my baby doesn't grind when going into reverse anymore. I can't even begin to tell you what that means to me. The pain was becoming almost physical every time I'd hear that grind. I had taken it to a car meet a few weeks ago, where I jammed it into reverse as quick and hard as I could so that maybe nobody would hear it grind over the sound of burnouts and engine revving. It has been a real sore spot on an otherwise incredible find.

    I went from trying to reverse engineer bench bleeding, to just easily popping off a ring clip so fast that I think I might have whiplash. This NEEDS to be common knowledge on the forums. I was considering paying a mechanic whatever they asked just to guaruntee that the system was bled. Who knows how much money this saved me...

    A note for anyone attempting this: Getting the clip to compress is the easy part. Getting it OUT of the hole while you have it compressed is the hard part. Or it was for me, at least. Even with the pliers. I used a pick with a curved end to lightly pry the ring out of the master cylinder while keeping the ring compressed using the pliers.

    I noticed that the fluid in the master cylinder is old fluid. Even older than the stuff I just flushed the other day. I might remove the ring again and repeat the process in order to get the rest of that old fluid out. It's probably about 26 years old, and I've switched to Dot 4 anyway. So I feel like it needs to go. And I want to make an instruction video anyway.

    Again, I can't thank you enough! I at least owe both you and the gentleman that made the video a nice cold beer. I would've been screwed without you.
     
  9. Dubious_Downfall

    Dubious_Downfall Member

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    Update:
    Took another short drive. I'm still getting resistance when trying to shift and it can still grind a bit into reverse. I'm going to bleed the slave as soon as I get a chance. I'm hoping that will solve it. I already tried repeating the method discussed. I got the old fluid out, but the clutch still feels nearly the same as the first time I did it. I'm hoping the slave just has a bit of air left in it. Otherwise it's likely to be a bad slave cylinder. Which I don't know how to check without dropping the transmission.
     
    Last edited: November 5, 2019
  10. 410Fortune

    410Fortune MUD SEASON 2.0 Staff Member Moderator

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    You can actually measure the amount of travel you are getting at the clutch

    What brand slave did you use?

    This video can be very helpful also


    It can also be worn synchros in the transmission from repeatedly trying to force through this issue
     
  11. Dubious_Downfall

    Dubious_Downfall Member

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    It has still been giving me grief. Bleeding the master DID help, but I still have problems shifting sometimes. Mostly just first and reverse, but a little bit into other gears if it's already giving me issues. I STILL haven't bled the slave, so that may very well solve the problem.

    I tried something earlier. I put the truck in first, pressed the clutch pedal to the floor, then revved the engine. The truck rolled forward. So I think that means the clutch isn't fully disengaging. So there's probably still an air bubble. Especially since it gets worse after driving.

    I'll report back after another bleed.
     
    Last edited: November 9, 2019
  12. 410Fortune

    410Fortune MUD SEASON 2.0 Staff Member Moderator

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    understood! Bleed that slave cyl!
     
  13. Centaurious

    Centaurious Active Member

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    Be aware that the clutch line runs down by the outside of the frame then goes up and over to the inside and over to the slave cylinder! Guaranteed air bubble location. (Curse you Ford Engineers !!$#*%$*^$$*$**%()))!!!!!!!!)

    I pulled mine out of the truck and strung it up and stretched it out and as others have said beat it with a screwdriver handle and pumped until it was un-pumpable.

    No troubles since.
     
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