Basic question. I just got a new OEM clutch slave cylinder that I hope to install in my '92 Talon TSi AWD today. The old one was leaking air and thus no good. To make it easier to bleed I bought a pair of Russell speed bleeders, which I'd previously installed on all 4 brake calipers and which have worked out well.

Thing is, they come with a coating of some graying substance that I'm not sure whether it's there to help seal the threads against leaks, make it easier to install, serve as threadlock, etc. And when I started screwing it into the slave cylinder bleeder opening, it met with resistance almost right away, due to this substance I assume.

So I'm wondering, am I supposed to lubricate the threads, with say brake guide pin silicone lube, or brake fluid? Or install it dry, as is, and don't worry about the resistance?

That's probably thread sealant. You shouldn't need anything else. Very smart to get the speed bleeders. Back in the day they didn't make those and it was always hell trying to get a second person to come and help me bleed them.

I believe it's to seal the threads. On regular bleeders I have to wrap the threads with tape to keep them from wiggling and letting air back in.
I don't remember the instructions saying anything about lubing them.

Vegas Smith said:

That's probably thread sealant. You shouldn't need anything else. Very smart to get the speed bleeders. Back in the day they didn't make those and it was always hell trying to get a second person to come and help me bleed them.

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I really had no choice as the only person I could corral to help me hated being out in the cold for the 5-10 minutes it took to do this properly, and I've had to do this multiple times due to what turned out to be a bad slave that despite several attempts just couldn't be fixed.

Anyway, looks like I don't have to add anything and the resistance is per design.

Yes, I believe that is just thread sealant, and some resistance would by normal. You shouldn't have to reef on it.(?!!!?) I also thought this was a good idea, but have not yet done it, so I hate to think I steered someone else down a bad road. I assume you compared the ends of the stock bleeder and the speed bleeder, and found them very similar? I actually noticed there are several brands (Russel was the one I was familiar with originally), but they all seem to have sealant on the threads (different colors). Shouldn't require lube, unless the mfr recommends it. I have to assume it is brake-fluid compatible.

As others already mentioned, without some sealing, air will simply leak through the untightened threads. With a normal bleeder under pressure, this is not a problem because the bleeder is only loosened during raised fluid pressure, then closed before the pressure is released (and subsequent mild vacuum to draw more fluid from the MC reservoir). I've more often done vacuum pump bleeding (one person), and have used caliper grease around the bleeder screw/ caliper body interface. The grease is way to thick to be sucked through the threads. I suppose teflon tape would also work, but I was always a little leery about compatibility with brake fluid.

The speed bleeder basically works more like the pressure bleed method, but without the repeated tighten/loosen sequence. It also would accommodate vacuum bleeding. Depending on the elevations of components, either or both can be used to chase every last bit of air out. No option for reverse-bleeding, of course, which is a third method that uses more specialized equipment (though not exactly exotic). It uses a second supply of fluid forced into the bleeder. I've never tried it, but some repair manuals and mechanics recommend it. It would be most helpful if air were hard to dispel near the MC for whatever reason. A dsm clutch should not require it.

I ended up just tightening the bleeder w/o adding any fluid or grease. I've heard that it's easier to snap a speed bleeder with too much torque since the center is hollow to accommodate the check valve, so I was careful to not tighten it too hard. To see if this was tight enough, I attached the bleeder tube to the nipple and pressed the pedal down a few times.

A little fluid actually came out, so it wasn't quite tight enough. But since I needed to bleed the slave, I just loosened it further, and bled it until there was no more air. Then I pressed on the end of the piston rod a few times to bleed the bore. I then removed the tube and tightened the bleeder, this time with a torque wrench using the FSM spec. I then reattached the tube, pressed both the rod and pedal again, and no fluid came out. For good measure I tightened the bleeder just a tad more, maybe 10 degrees.

It worked. The pedal has real resistance and disengaged the clutch properly. I confirmed by lowering the car and driving it back and forth a few times. I've yet to give it a test drive. It was getting late so I hope to do that tomorrow (don't want to get stuck somewhere after dark with a car I'm not yet 100% sure about). I'll make sure to carry all my tools with me (I've been using the car as storage anyway so that shouldn't be a problem, although I will soon have to figure out where to put it all).

Seems to me that speed bleeders have two obvious weak points. One, you can more easily snap them since they're hollow. And two, air can leak through the threads, especially after multiple cycles of tightening and loosening removes the sealing material. I suppose that you can apply new sealant, but the whole idea seems kind of hokey. I'll check from time to time as I drive the car to see if the master cylinder fluid level goes down and there's brake fluid leaking out the bleeder.

I wonder if it's possible to design a speed bleeder that has a check valve AND a mechanical mechanism for sealing the bleeder, so you don't have to worry about leaks and sealant and don't even have to bother with a wrench to loosen it during bleeding, a little like a radiator cap but using a different mechanism, like a banjo bolt that you twist to open and shut. It's not like you bleed brakes and slaves that often, but it's enough of a pain when you do that this might be worth it.

Anyway, hopefully a new slave fixed the issue and the car's ready to get inspected. Wish me luck!

Sounds like it all worked and you’ve discovered the Next Big idea, too. Glad you tamed that misbehaving clutch. Hope the test drive feels sweet!

Thanks, but it's still a long road ahead. So much more to be done. Particularly the trans. It felt like it needs quite a bit of work. The car moved, but with issues. At least the clutch and brakes were fine and the engine sounded good. It's amazing how many parts a car has--and they all break eventually.

Hell, I spent the better part of an afternoon this past weekend extracting a broken battery hold clamp bolt from the strut tower. Thing wouldn't budge. Put the tap and die set I bought recently to good use.