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2015 STI Broken Clutch Master Cylinder

Transmission/Drivetrain 
5K views 15 replies 6 participants last post by  VA STI 
#1 · (Edited)
I was leaving work yesterday night and when I pushed the clutch pedal in to start it I heard a ping noise and the pedal dropped to the floor. The clutch engagement point was almost at the floor so I pulled it out of gear and waited for the car to warm up (it was -15C here in Canada). After that the transmission wouldn't go into gear.

It seems as though my master or slave cylinder is leaking or blew a seal, or the hose sprung a leak. Has anyone had this happen on VA STIs? My car only has 70000km on it so I never expected a master to fail this early. I took a quick look around and it appears as though there is some fluid below the master cylinder but I can't see if its coming from the master or slave. I'll have to limp the car home in order to pull the intercooler off and have a proper look at the problem. Seems to be kind of a downer to have this happen so soon. I called the dealership and the master and slave are not covered under the 5 year powertrain warranty.
 
#2 ·
I have not had that issue, and I'm at a bit higher mileage (~95000 km) with some track time. That being said, after some track time, the fluid in the clutch sounds pretty terrible. Like a groaning when I depress the clutch. I've never flushed the fluid in the clutch itself before either, though I've done quite a few brake bleeds.

That aside, a tip for pulling the IC off I thought I should share is to get an extension on your socket wrench and undo the clamp holding the elbow hose to the y-pipe on the back of the IC, as opposed to messing with the visible clamp that's on the turbo-side. Then you can slide the IC out of the turbo and TB hoses in one straight motion, rather than that angling nonsense.

Not sure how much of this is common knowledge, but it's been a life saver for me, as reinstalling the IC at an angle to slip the hose over the turbo outlet AND into the TB coupler at the same time was a pain and often resulted in boost leaks for me. Leaving the elbow hose on the turbo lets you reinstall the IC in a straight, fluid motion, you just need a good size extension for your wrench.
 
#3 ·
I have not had that issue, and I'm at a bit higher mileage (~95000 km) with some track time. That being said, after some track time, the fluid in the clutch sounds pretty terrible. Like a groaning when I depress the clutch. I've never flushed the fluid in the clutch itself before either, though I've done quite a few brake bleeds.
I've had a couple track days as well but I flushed the brake fluid (and clutch fluid because they share a reservoir and I flushed through the slave) with Motul RBF600 so that should be good, though its been around 2 years on this fluid so it may be time for another flush.

That aside, a tip for pulling the IC off I thought I should share is to get an extension on your socket wrench and undo the clamp holding the elbow hose to the y-pipe on the back of the IC, as opposed to messing with the visible clamp that's on the turbo-side. Then you can slide the IC out of the turbo and TB hoses in one straight motion, rather than that angling nonsense.

Not sure how much of this is common knowledge, but it's been a life saver for me, as reinstalling the IC at an angle to slip the hose over the turbo outlet AND into the TB coupler at the same time was a pain and often resulted in boost leaks for me. Leaving the elbow hose on the turbo lets you reinstall the IC in a straight, fluid motion, you just need a good size extension for your wrench.
This is a great idea that never occurred to me. I'll definitely do this when I replace the master cylinder. Thanks for the tip.
 
#5 ·
when I pushed the clutch pedal in to start it I heard a ping noise and the pedal dropped to the floor. The clutch engagement point was almost at the floor so I pulled it out of gear and waited for the car to warm up (it was -15C here in Canada). After that the transmission wouldn't go into gear. . . . it appears as though there is some fluid below the master cylinder but I can't see if its coming from the master or slave. I'll have to limp the car home in order to pull the intercooler off and have a proper look
Your clutch is or isn't working? Not going into gear is normal for a non-working clutch. If this is the situation I'd give you odds the issue is not your master cylinder. But you wrote it has a low engagement point and that you are expect to be able to limp it home. Souns like your clutch is working and might well have a fluid issue.

Inspect the slave cylinder and hose area too.

Wait!

I heard a ping noise and the pedal dropped to the floor.
Sounds like the return spring broke or popped off! But then you' be able to shift. The engagement point should not change, only the travel before disengagement.
 
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#11 ·
sort of - you flush and bleed brakes at the far end - the calipers. To flush the "clutch fluid" you'd do the same - at the slave cylinder.
 
#14 ·
update: I was able to drive the car home clutchless shifting and starting it in gear at red lights. After taking off the intercooler and manually actuating the slave cylinder I saw fluid spitting out of the bottom of the clutch master cylinder. So the master cylinder is broken somehow. I've ordered a new one ($250 CAD) and will be installing it once the part gets here.

How should I go about bleeding this thing? It doesn't have its own reservoir so I'm not sure how I would bench bleed it. The bleeder for the slave is on the bottom of the slave cylinder so I'll have to remove it first in order to bleed it. I'll have to remove the starter in order to unmount the slave cylinder from the transmission which is a pain.
 
#15 ·
#16 ·
So I replaced the master cylinder. Taking off the bottom bolt for the starter was a real bitch, I'm not sure if the newer EJs just have more shit on that side blocking it. Bleeding the clutch wasn't too bad and now everything works again. Really weird that the master broke so early in it's life.
 
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