My clutch pedal was sticking a little so I decided to try and use a MityVac to bleed the lines. When I put the plunger tip down into the master cylinder and tried to get up to 10Hg a large amount of bubbles came up the tube and I was not able to hold vacuum. When I pulled the vac hose from the reservoir some bubbles came up from the bottom of reservoir lowering the fluid level, but not enough that I let it go dry. Now the pedal goes to the floor and it sounds like my master cylinder is empty. I wasn't having this problem before I tried to bleed with the MityVac so I'm thinking it isn't a faulty part.

It is a Tick Performance Master Cylinder if that matters and I did replace the zip ties with hose clamps. I'm going to bleed it the traditional way later on today once some help comes over, I just wanted to know if anyone knew what was going on with the MityVac.

Yes, I have read and read about this. Some seem to have luck and some don't.

 

Either you have a lot of air trapped in the system or you have a leak somewhere is why you keep puliing air bubbles. Bleeding it traditionally won't matter if you do have a leak somewhere.

 

We bled the master cylinder and the pedal drop and spongy pedal is gone. The only problem now is the pedal wont come all the way back up. I'd say it comes back 75% then it doesn't have any resistance to it the last 25%. I'm going to bleed the slave next and see what happens.

 

Ive never seen this method of pulling fluid up through the master. I always pull from bottom down, utilizing the master as a reservoir. It seems that pulling fluid up from the bottom would induce air down low. Or am I mis-reading what your saying here?

 

This is the procedure I used for bleeding the clutch master and slave cylinder.

 

I had a clutch pedal that started acting funny, sometimes not returning all the way, not responding to bleeding. Did a fluid flush and the old fluid that came out was black. It was better but problem came back again and then the pedal did something that could have been in a Las Vegas magic show... it pulled down to the floor at night. No joke, all the way to the pedal stop. And yes, that seems to defy physics and Tilton engineers couldn't explain it either. I would pull the pedal up and drive fine all day and then find the pedal all the way on the floor again the next morning.

Anyway, my magic sinking pedal ended up being fixed with two things:

(1) I pulled the master cylinder (Tilton) and found it full of a black sludge. That sludge was sometimes blocking the fluid return. The hose between the master cylinder and the fill reservoir was breaking down and formed that sludge. I cleaned out the cylinder and replaced the hose. Then I flushed the **** out of the system hoping none of the sludge was stuck in the slave cylinder.

(2) The pedal still sometimes wouldn't return all the way and I was out of ideas. On the advice of Tick, I removed the helper spring from the pedal. That fixed the problem for whatever reason and it's never come back. I actually like the feel better now, I get more feedback in the bottom half the pedal.

If you put a vacuum on the clutch fill bottle then it will pull air past the seals and you'll get bubbles until you stop. Everything above the bore of the master cylinder is just reservoir and doesn't seal against much pressure or vacuum.

Gravity bleed the lines to pre-fill and then snap the hydraulic line to the transmission. Then get the *** end of the car high in the air so the nose of the trans is pointing downward. You gotta do this to tilt the slave cylinder so the bleed port is higher than everything else, otherwise air gets trapped. Pedal bleed with smooth, slow strokes. Never open the valve unless there is pressure on the pedal, and always close the valve with the pedal still in downward motion moving fluid. If you push the pedal too fast then it will emulsify the bubbles into a millions of little teeny tiny bubbles that are hard to purge. If that happens then just walk away for a little while until all the bubbles collect into bigger bubbles.

 

I took the car for a drive yesterday and it is drivable, the pedal just isn't the same as before. Most of the resistance is on the bottom half of the pedal travel. I'm going to try to put the rear end of the car up in the air and bleed that way. I also didn't have pressure on the pedal before cracking the bleeder screw. I'll make sure I do that correctly. How many pumps or reservoir fills does it usually take to bleed out the air?

 

Good luck! Don't short cut anything, I tried vacuum bleeding and it never worked for me. Upgraded to the Tick Performance adjustable and new slave and blew a seal causing a rebuild. Take it slow and don't worry about reps but results. I'll be doing this soon myself. I installed the speed bleed line to make it easier and will make sure all dark fluid is flushed out and clean this go around.

 

I'm still battling this clutch bleed. I was thinking it was a bad slave until this morning I went out to check the fluid and it was black, so I sucked some out and refilled it. This is when I noticed a black sludge coming out of the reservoir. I'm beginning to think I have your sludge problem and need to spend a weekend thoroughly bleeding and cleaning.

 

I would do a full flush. If you have a bleeding line it will be easy enough to do but if not I think you can get a hose that can fit over the OEM bleeder port but all that will help with is directing the brake fluid someplace other than in your transmission case. You will need to flush ALL the sludge out. I replaced the OEM bleeder valve with a speed bleeder line and this helps a lot in flushing as well. Some out there have 1 way valves that make is a 1 person job which is the easiest. I would flush it until the fluid is 100% clear coming out. Hopefully it didn't look like this.

 

My fluid wasn't that dark, but it was close to the color of tea. I thought we had all of the crud flushed out because nothing but clear was coming out of the slave for 4-5 reservoir top offs. Then we used my car for a gender reveal burn out for my daughter and more of the dark stuff appeared in the reservoir. I have a Tick Performance speed bleeder ready to install I just need the time. Thanks for your help.

 

I took my car to a "performance" shop today so they could check out my clutch situation. They bled the clutch and took it for a test drive. They came up with the same results I'm having and said it was most likely the slave or master cylinder. I have a new Tick Performance master so I'm kind of ruling that out. Do slave cylinders go out gradually? My problem hasn't gotten any better or any worse. Anyways, they wanted to charge me right at $1,000 to change out the slave. IF it needs changing out I will definitely be doing it myself.

 

Once you get the master cylinder out of the car it disassembles very easy for cleaning. Take care not to nick or damage seals. You can see pictures in post #1309,
https://www.thirdgen.org/forums/ltx-...ml#post6331422

 

I’ve actually got my fluid looking great. After a week of driving it still looks new. The shop that bled my clutch said they used a power bleeder and it was the best way to do it. My pedal seems to be worse now as far as sticking. Is it possible they introduced more air?

I have a new GM slave ready to go in and I am researching a new clutch also. Just don’t want to take the plunge until I’m sure this is what I need instead of a cheaper fix.

 

I did not solve my problem until I got hands-on with the parts. Sounds like you are at that point too. It's not fun, I'm not going to lie.