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Old 11-15-2012, 02:31 AM   #1
Scooby Specialist
Member#: 188132
Join Date: Aug 2008
Default No pressure buildup on clutch slave/master cyl/lines

So this is an 02 WRX motor in a 2000 RS. The tranny is from a 2004 WRX and the slave/master from an 02 WRX.

Today I decided to bleed the clutch system in order to be able to install the intercooler. Below are the steps I did and the results.

1. Filled master cylinder with Dot3 fluid
2. Opened the slave cylinder bleeder valve
3. Started pumping the clutch pedal, but no pressure was built up and no fluid was being passed to the slave cyl. The fluid on the master cyl stayed steady.
4. I adjusted the fork inside the cabin, nothing.
5. Took off the fork in the cabin and pumped it by hand, a little fluid did leave the master cyl.
6. I completely removed the bleeder valve and pumped it, did feel the air coming in/out the hole.
7. We tried and tried diff combos and all of a sudden with the bleeder closed the pedal got hard. I then loosen the bleeder to let out air. After tightening, no pressure again.

Anyone have any ideas?
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salvi is offline   Reply With Quote
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Old 11-15-2012, 05:49 AM   #2
Scooby Specialist
Member#: 284792
Join Date: Jun 2011
Chapter/Region: RMIC
Location: Vanilla Valley, CO
2011 STI


Bleeding the clutch system is very much like bleeding your brake system. Bleed air out starting from the master cylinder. Otherwise you'll bleed forever and may not get a firm pedal. Did you bench bleed the master? You should do that first before proceeding to the next step.

When the slave cylinder is bolted to the tranny, it doesn't sit level. You need to unbolt the slave cylinder and clamp/hold the rod that operates the clutch fork. Hold the slave cylinder level during the bleeding process in order to get all of the air out. Now the process you used to bleed the system (from how you described) was completely wrong. You don't just open the bleeder nipple and pump away. You need to create pressure in the system to PUSH the air out, then you need to seal the nipple BEFORE lifting the pedal up to prevent that air you just pushed out from going back into the system. Follow these simple steps:

*Get your wrench around the bleeder nipple and put your tubing around the nipple then into a container to catch the fluid. Do not open bleeder nipple.

*Hold the slave cylinder level and have your partner press the pedal to the floor.

*Open the bleeder nipple to let out the pressure built up in the system.

*Close the bleeder screw.

*Have your partner lift the pedal back to the closed position.

*Repeat steps 2 through 5 until no more air comes out of the bleeding line.

Note: air may not come out the first couple of pumps.
RoadKillDMD is offline   Reply With Quote
Old 11-15-2012, 09:31 AM   #3
Scooby Specialist
Member#: 220971
Join Date: Aug 2009
Chapter/Region: South East
Location: West, NC
2002 WRX 223K Mi.


I just did the clutch in my '02, I had 2 issues. That stupid anti dump valve on the operating cyl. You can remove the guts of it and solve a lot of the bleed issues. The second problem was operating cyl would stick and not extend by the internal spring pressure back out, drawing fluid back in.

I'd clean or replace, and while youre at it ditch the anti dump valve. Mine now operates better than it ever has.

Heres the hard way:

The easy way is to remove the large bolt, and just pull the springs out of the housing the above instructions tell you to eliminate all together.
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Old 11-15-2012, 12:37 PM   #4
Scooby Specialist
Member#: 188132
Join Date: Aug 2008

I'm going to try to bench bleed the system again. I did it last night but there was just no pressure buildup.

I'm going to remove the line from the master cylinder and feed fluid from the hole in hopes of reverse bleeding the master cylinder.

Blktrax, don't know if I want to modify it that much and end up making it a paper weight.
salvi is offline   Reply With Quote
Old 11-16-2012, 02:43 AM   #5
Scooby Specialist
Member#: 188132
Join Date: Aug 2008

Alright, we worked on it for a couple of hours today, but finally fixed it. I bought a MityVac from Oreilly. We put the pump on the bleeder of the slave and tried to bleed the system for at least two hours. At first we were getting nothing but air, but finally we did get fluid. But the pedal still had no pressure.

With the help of my friend E, we took the lines off testing with the pump to see if were getting pressure all the way to the master cylinder. The lines were fine. We noticed that the master cylinder's fluid did not drain out even after we disconnected the metal line.

Luckily I still had a spare master cylinder. I added fluid to it and it easily drained out. We swapped them and easily bleed the system with the Vac. Pedal is now nice and firm.
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