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Clutch keeps losing pressure.


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5 hours ago, DIY 1985 said:

When a slave cylinder is bad, there could be a bit of rust, some crud, and wear on the seal.  I could see how this could cap the system when the slave piston travels in one direction (pressure from the master).  The pushrod might also be pushing back at an angle, and not on the exact axis of the cylinder and piston.  Wouldn't the master create negative pressure when the pedal is no longer depressed, and until it travels to the point where its piston seal meets the fluid from the reservoir?  With negative pressure on the system, that could draw air in at a half-functioning slave cylinder?

 

Oh, I meant to address this post.  The slave piston was some weird homemade thing.  It was like a piece of all-thread with some nuts on it.  It fit through the little hole on the transmission fork.  Not knowing what I was doing, I tried putting the piston into the hole on the fork with the new slave cylinder.  It popped right through.  I was pretty frustrated, at this point in fixing things, last night, so I yanked that piston out and put in the little homemade looking deely-bobber.  It's working, but there's a part of my brain that says that was a very stupid thing to do. 

 

But, just because something is a stupid idea, doesn't mean it's a bad idea. 

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One benefit from replacing ALL the parts in a system is that you get to rule out parts as the problem. Saving a $9 hose and risk having the same problem - not worth it.

 

You can't always see a hose going bad. As I mentioned before, they can swell on the inside and the tough braid keeps it from showing on the outside.

 

 

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14 minutes ago, Stoffregen Motorsports said:

One benefit from replacing ALL the parts in a system is that you get to rule out parts as the problem. Saving a $9 hose and risk having the same problem - not worth it.

 

You can't always see a hose going bad. As I mentioned before, they can swell on the inside and the tough braid keeps it from showing on the outside.

 

 

 

I agree.  But, replacing the hose means taking a bunch of stuff apart and then re-bleeding the lines.  I just don't have it in me, today. 

 

Either it'll be fine, for a while, or AAA will have to come get me...again.  On the bright side, it'll be pretty easy to figure out what went wrong when that goes wrong! 

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Sometimes bleeding is difficult because if the bleeder screw is opened too much, air can get drawn thru the threads on the bleeder.  They make special bleeder screws, that have a thread locker type of sealant so air doesn't get drawn thru this kinda sloppy fit, but, I've heard of folks who use teflon tape to do the same thing.  The special bleeder screws also have a one-way valve, internally, but, I've seen reports that the spring that keeps the valve requires extra pressure, so it makes getting air bubbles harder to remove in the overall system.  If you just barely crack the bleeder screw, it will be fine, typically.

 

Also, consider the overall configuration of the bleeder set-up, you can make it harder if the hose is working against your efforts.

 

I'd like to see pics of the hack.  The funny push rod and all.

 

Sometimes hydraulic fittings can be a battle that isn't always won.  A flare-nut wrench can strip the hex on the flare nut, no problem.  It does this because flare nut wrenches are usually inadequate for breaking the nut free after it rusts up a bit.  If you use a Vise-Grips (vice grips) to prevent the flare nut from distorting (opening up) when you turn it, it will work far more effective.

 

1121341216_FlareNut2.thumb.JPG.a16e447b9092a86c8b6d2e98d44b9a2c.JPG

 

 

1943094429_FlareNut1.thumb.JPG.b81012b642a3de14f6a4bb23ba35e7bc.JPG

 

I was able to free all of the hydraulic lines, on my other rust bucket, without stripping a single one.

 

I also found that there was no reason to really replace the hard lines, just blow them out with compressed air, but, new lines were available as new and already formed, they also had already arrived, so they got installed.

 

When you try to unfreeze it for the first time, grab the locking wrench with one hand, and the flare nut with the other.

 

 

 

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The special bleeders are called Speed Bleeders by Russell; I don't have experience with them, nor do I recommend them.  The teflon tape around the male threads on the bleeder screw might also be kinda compromised / not OEM - subject to loosening, possibly?  I just used that as an example of how bleeding can be trouble in that air might get in thru the loose fit on the threads of the bleeder screw.  Once you understand that the bleeder screw should only be cracked open just enough, you will get by without any compromising modifications to equipment, which could get you stranded.

 

I use a really heavy glass jar (Straus Cream) from the grocery store, as a bleeder bottle; I drill a hole in the cap to fit the 1/4-inch tubing.  It allows me to use vinyl tubing that would otherwise knock over the empty bottle, especially when it is cold outside.  The clear vinyl tubing comes from a bulk spool at Ace Hardware.

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18 hours ago, DIY 1985 said:

Sometimes bleeding is difficult because if the bleeder screw is opened too much, air can get drawn thru the threads on the bleeder.  They make special bleeder screws, that have a thread locker type of sealant so air doesn't get drawn thru this kinda sloppy fit, but, I've heard of folks who use teflon tape to do the same thing.  The special bleeder screws also have a one-way valve, internally, but, I've seen reports that the spring that keeps the valve requires extra pressure, so it makes getting air bubbles harder to remove in the overall system.  If you just barely crack the bleeder screw, it will be fine, typically.

 

Also, consider the overall configuration of the bleeder set-up, you can make it harder if the hose is working against your efforts.

 

I'd like to see pics of the hack.  The funny push rod and all.

 

Sometimes hydraulic fittings can be a battle that isn't always won.  A flare-nut wrench can strip the hex on the flare nut, no problem.  It does this because flare nut wrenches are usually inadequate for breaking the nut free after it rusts up a bit.  If you use a Vise-Grips (vice grips) to prevent the flare nut from distorting (opening up) when you turn it, it will work far more effective.

 

1121341216_FlareNut2.thumb.JPG.a16e447b9092a86c8b6d2e98d44b9a2c.JPG

 

 

1943094429_FlareNut1.thumb.JPG.b81012b642a3de14f6a4bb23ba35e7bc.JPG

 

I was able to free all of the hydraulic lines, on my other rust bucket, without stripping a single one.

 

I also found that there was no reason to really replace the hard lines, just blow them out with compressed air, but, new lines were available as new and already formed, they also had already arrived, so they got installed.

 

When you try to unfreeze it for the first time, grab the locking wrench with one hand, and the flare nut with the other.

 

 

 

 

That's pretty clever with the vice grips on the flare nut wrench.  I just used the first pair of squeezers I could find to loosen the hard lines as they came pre-stripped from some previous owner. 

 

I'll get a picture of my "fluid pump" that I used.  Gonna wait until it gets light out, though.

 

I took the car for some test driving and it's running well.  I need to test drive it more and do more checks for leaking.  I think it's good, but I've been wrong about this sort of thing before and I'm not a huge fan of surprises.  Though, I'm keeping my cooking syringe in the car, should the lines ever need to be bled again.

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These are another good option for brake line fittings (I can't remember if this is the right size, they make a range of sizes):

 

https://www.amazon.com/Tools-VISE-GRIP-Locking-Wrench-Cutter/dp/B00004SBBD/

 

My family had a full size van and the driver rear drum brake started dragging. Turned out to be the soft line developed a one-way valve internally 😅

 

 

31a1SUlUTSL._AC_SY1000_.jpg

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Alrighty, here are the pictures of my "fluid pump."

 

syringe1.jpg.07640f0adcec648c53fd4f63964a2b85.jpg

 

So, first you take the little hose there and put the green bit into the full reservoir of dot3.  Then, suck up nearly a full hose worth.  If you were born with three functioning hands, you could use the syringe to do that.  I was not, so I just sucked it up with my mouth.

 

syringe2.jpg.bc14522d08134608ba446e8a1d8af118.jpg

 

Attach the fluid filled hose onto the syringe, make sure the plunger on the syringe is pulled out before you connect them, and then jam that little green end as tightly as you can into the hole in the bottom of the reservoir.

 

Plunge the plunger.  But, not so much that it runs out of fluid.  You don't want to shoot air in there, obviously.

 

Then, pull the green bit out of that little hole, refill the reservoir, suck up more dot3 into the hose, jam it back in and plunge more.  Repeat until Dot3 is squirting everywhere and making a big ass mess.

 

Before I bought the cooking syringe, I tried to just blow the dot3 through the system by mouth.  I do not have the lung strength to achieve this.  Then, I was going to use my air compressor.  But, I left it out all winter and it is broken.  So, I walked to Safeway and bought a cooking syringe. 

 

If one were so inclined, you could take the plunger out of the syringe and fill it with dot3.  Push until it squirts out of the tube and then jam it into the hole and squeeze a full syringe of fluid through the lines.  I felt like the chance of air bubbles was a lot higher that way, though, so I did it my way, instead.

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I have one.I always just put a new clutch or brake reservoir on,add fluid and bled it.Never had a problem.My hose at the slave cylinder cracked and came apart long ago,so I replaced.It was still working good but I knew in time it would go out.I have never bled the clutch or brake reservoir.The air goes out at the slave cylinder when bleeding.

Edited by Thomas Perkins
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