2G New to DSM! Clutch pedal issue.... drops to floor.

[Dave_UK]

Before you all say it, yes I have used the search bar But the threads that came up were from 09 etc and the site encountered issues trying to load them, my guess is they are archived due to age?

In any case... So I have a 99GST FWD manual (obviously) which as far as I can tell, still has a stock clutch, slave cylinder etc. Pedal just goes straight to the floor, doesn't come back up. Have topped the fluid up, pumping the pedal gets the occasional air bubble but nothing to suggest a serious leak, and there isn't any fluid on the floor.

Before I start taking things apart, any of the gurus on here able to point me in the direction of common problems or easy things to check first? Thanks in advance.

(First time working on a DSM hydraulic system so all help is appreciated!)

 

[miliman13]

did you confirm you have motion on the fork from the slave?

It sounds like it’s your master (guessing).

It’s never a bad idea to replace both and use a bleeder kit to eliminate bubbles.

 

[Justin DuBois]

I’ve had this. If bleeding the clutch does not resolve it, It is time to replace slave and master cylinder parts.

 

[dwb]

If this happened suddenly, typically that means you have a hydraulic leak and/or air in the system. Did the reservoir ever go empty? Have you tried bleeding it?

 

[chrisman287]

This is generally the same for most if not all manual cars.

Check for fluid leaks. You really shouldn’t have had to top off the fluid. If none are found you can try bleeding the line but I’d start with replacing the slave at least. It’s the easiest to change. Bleed it well. If the problem persists, change the master.

 

[chrysler kid]

change the master and the slave. the slave is inexpenisive compared to the master, and it is not uncommon for one to fail and then the other fails shortly after

 

[CKOPOCT]

Only 3 possibilities:
1. Fluid leak = no pressure to bring the pedal back up. Check the reservoir, and if fluid is low begin checking all components, lines, and junctions to see where it's leaking

2. Seal rupture in the master/slave = fluid just slips past the seal so you're moving the pedal and plunger but not actually doing any work. Have someone move the clutch pedal while you watch the transmission to see if the fork moves. If not, replace both the master and slave.

3. Broken clutch fork mechanism = the hydraulics are fine but the fork is snapped, the slave pin came dislodged, or some other mechanical error is causing the clutch not to work. If the hydraulics are fine and the slave pin moves properly, and if you apply resistance to the pin and the clutch pedal seems to work properly then, probably time to pull the tranny and see what's up.

 

[RamenPride]

Pull back the boot on the slave cylinder, and you'll probably find it full of fluid. As mentioned already, just replace the master and slave. If they're still original, they're pretty worn out at this point.

 

[Dave_UK]

So after some messing around, I have decided to just replace the master and slave cylinders for the clutch, but as far as I can tell these are no longer available from Mitsubishi. Seems like Exedy still offer them but I am not 100% sure on the part numbers.

As far as I can tell, MD749822 is the OEM Mitsubishi number for the Slave, and MB910562 is the number for the Master cylinder. These cross over to Exedy part numbers SC589 & MC188 respectively (info from TMZ Performance). But Exedy themselves list the Master cylinder as MC401 (MC188 is for GSX only) and don't list anything for the Slave cylinder.

Any guidance or corrections would be appreciated and links to purchase the correct parts even better! Thanks in advance.