Clutch pedal loses pressure intermittently...master or slave cylinder?

joserpm · 12-27-2009, 03:54 AM

Just like the title says. I have a stock 07 WRX with 51,000 miles, and the clutch pedal feels like it has no pressure at all. I can still shift the car, but it jumps when I release the clutch because the release point gets to be really low.

I could drive it for a week, and not feel a thing, then BAM...the problem comes back...whether the car's hot or cold...whether I drive 10 miles or 50 miles. It just comes and goes randomly.

I checked and I see no leaks, and the fluid has its normal color (aka not blacked out or dark). The reservoir is still full, and again, no damp/wet areas, which makes me believe that it could be the master and/or slave cylinder.

So first question: is it a hard job to tackle? I'd rate myself a 3.5 out of 5 when it comes to mechanical experience. I can adjust valves, install shifters, etc. aka nothing that involves tearing the engine or tranny apart.

Second question: I asked this somewhere else too, but what the heck..sue me!

Where's a good place to get the needed part(s) at a good price? I'm guessing somewhere online would be cheaper than the brick-n-mortar store.

and final question: I've seen these 'rebuild kits' for both the master and the slave cylinders. Is that what I need, or do I need to fork out the extra dough $$$ for actual master and slave cylinders?

Gracias amigos? Hope you had a safe holiday.

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CallMeJag · 07-19-2010, 01:32 PM

Bump for opinions on this. I'm having the same problem with my 06 WRX. The pedal will work perfectly one day, then I get the car on the next day and there is practically zero pedal pressure. The clutch engages pretty much at the floor. The problem works itself out after driving for about 20-30 minutes.

Help!!

Fierysun · 07-19-2010, 03:49 PM

Have you tried bleeding it? Maybe there's air/water in the lines.

CallMeJag · 07-19-2010, 04:08 PM

^ that's exactly what my shop is telling me. I'm going in this weekend to get a fluid flush and a braided stainless line installed for good measure.

THEVERGE · 07-19-2010, 04:25 PM

I had the same problem. I bought the rebuild kit for both the master and slave cylinder. I also honed the insides of both cylinders. This is really easy, you should be able to do this all yourself.

I also removed the little ufo looking thing on the bottom of the master cylinder. I plugged it with a bolt and copper washer.

This completely fixed the problem.

Big-E · 07-19-2010, 09:03 PM

At less than a year of having my car, there was 'black stuff' at the bottom of the clutch master reservoir. Sucked that stuff out and flushed it.

To your problem. Did you change the clutch hose by any chance? I had one leak on me a little on the master side.

Otherwise, take the advise of those above and flush out the system and see what that does for you. Then take it to the next step if necessary.

babaganush · 04-24-2013, 03:13 PM

I know this thread is really old but Im having the same problem. Did you ever resolve the issue?

12-27-2009, 03:54 AM	#1
joserpm Scooby Newbie Member#: 145002 Join Date: Apr 2007 Chapter/Region: South East Location: Lakeland, FL Vehicle: 2007 Impreza WRX WR Blue Pearl	Clutch pedal loses pressure intermittently...master or slave cylinder? Just like the title says. I have a stock 07 WRX with 51,000 miles, and the clutch pedal feels like it has no pressure at all. I can still shift the car, but it jumps when I release the clutch because the release point gets to be really low. I could drive it for a week, and not feel a thing, then BAM...the problem comes back...whether the car's hot or cold...whether I drive 10 miles or 50 miles. It just comes and goes randomly. I checked and I see no leaks, and the fluid has its normal color (aka not blacked out or dark). The reservoir is still full, and again, no damp/wet areas, which makes me believe that it could be the master and/or slave cylinder. So first question: is it a hard job to tackle? I'd rate myself a 3.5 out of 5 when it comes to mechanical experience. I can adjust valves, install shifters, etc. aka nothing that involves tearing the engine or tranny apart. Second question: I asked this somewhere else too, but what the heck..sue me! Where's a good place to get the needed part(s) at a good price? I'm guessing somewhere online would be cheaper than the brick-n-mortar store. and final question: I've seen these 'rebuild kits' for both the master and the slave cylinders. Is that what I need, or do I need to fork out the extra dough $$$ for actual master and slave cylinders? Gracias amigos? Hope you had a safe holiday. * Registered users of the site do not see these ads.

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07-19-2010, 01:32 PM	#2
CallMeJag Scooby Specialist Member#: 129096 Join Date: Oct 2006 Chapter/Region: SCIC Location: Rancho Santa Margarita, CA Vehicle: '06 WRB WRX Boosting @ idle.	Bump for opinions on this. I'm having the same problem with my 06 WRX. The pedal will work perfectly one day, then I get the car on the next day and there is practically zero pedal pressure. The clutch engages pretty much at the floor. The problem works itself out after driving for about 20-30 minutes. Help!!

07-19-2010, 03:49 PM	#3
Fierysun Scooby Specialist Member#: 82745 Join Date: Mar 2005 Chapter/Region: SCIC Location: So Cal Vehicle: 2005 Subaru STI 2003 WRX Wagon	Have you tried bleeding it? Maybe there's air/water in the lines.

07-19-2010, 04:08 PM	#4
CallMeJag Scooby Specialist Member#: 129096 Join Date: Oct 2006 Chapter/Region: SCIC Location: Rancho Santa Margarita, CA Vehicle: '06 WRB WRX Boosting @ idle.	^ that's exactly what my shop is telling me. I'm going in this weekend to get a fluid flush and a braided stainless line installed for good measure.

07-19-2010, 04:25 PM	#5
THEVERGE Scooby Newbie Member#: 127421 Join Date: Sep 2006 Chapter/Region: MWSOC Location: Eaton, Ohio Vehicle: 2002 Subaru WRX WRB	I had the same problem. I bought the rebuild kit for both the master and slave cylinder. I also honed the insides of both cylinders. This is really easy, you should be able to do this all yourself. I also removed the little ufo looking thing on the bottom of the master cylinder. I plugged it with a bolt and copper washer. This completely fixed the problem.

07-19-2010, 09:03 PM	#6
Big-E NASIOC Supporter Member#: 123843 Join Date: Aug 2006 Chapter/Region: NESIC Location: Greenwich, CT Vehicle: 2006 SGM WRX S2 Let LED's light your way!	At less than a year of having my car, there was 'black stuff' at the bottom of the clutch master reservoir. Sucked that stuff out and flushed it. To your problem. Did you change the clutch hose by any chance? I had one leak on me a little on the master side. Otherwise, take the advise of those above and flush out the system and see what that does for you. Then take it to the next step if necessary.

04-24-2013, 03:13 PM	#7
babaganush Scooby Newbie Member#: 336122 Join Date: Oct 2012	I know this thread is really old but Im having the same problem. Did you ever resolve the issue?