2G Clutch Pedal soft/sticks

[unplugme71]

Replaced the clutch master and slave with brand new OEM parts. Bled the system. Seemed to work fine, until after driving the car for 10 minutes it would start to get soft and stick. It usually always comes back up, but a lot slower and with very little pressure.

So I took it to my buddy's shop. He didn't notice any air in the line, but re-bled the system. Problem went away for about a week. Then after 10 minutes of driving, same thing.

Take it to get brand new tires and had the shop check it out. They said no leaks, bled the system free of charge. 10 minutes later, same shit.

Now I'm at the Mitsubishi dealer, they are telling me its fine and that there's no air in the system or leaks. They aren't sure why it doesn't happen right away, only after 10 minutes of driving.

(Note, the car is already warm before I start driving)

I'm totally lost as to what the issue could be and 3 different shops don't have an answer for me. I even asked other Mitsubishi techs, and they were surprised to know that it was replaced and not leaking as well.


Car is FWD with 185,000 miles.

 

[twicks69]

Have you physically disassembled the clutch master cylinder and slave cylinder and checked the internal seals? There are two piston seals on both cylinders. One inner, one outer. If an inner seal is damaged it won't leak but will bleed pressure while an outer seal damaged would cause visual leakage and loss of pressure. As well you may have another issue going on with the clutch as well, but I still think it is a hydraulic issue.

 

[unplugme71]

I have not disassembled anything, but I'm hoping that there are no internal leaks considering they are brand new (<50 miles)

 

[mnelsen]

This topic has been covered a million times. Maybe you should use the search function and I know you'll find an answer in less than five minutes. And everyone else is going to tell you to adjust your clutch. Sounds like you need a new clutch then if the Mitsu dealership says it's not leaking.

 

[T is for TURBO]

This topic has been covered a million times. Maybe you should use the search function and I know you'll find an answer in less than five minutes. And everyone else is going to tell you to adjust your clutch. Sounds like you need a new clutch then if the Mitsu dealership says it's not leaking.

What? How do you deduce that he needs a new clutch? Nothing helpful in your post.


OP- Tim is probably right, since he probably know the driveline of these cars better than anyone. With that said, I had a similar issue with mine. It wasn't a weak "srping back" but it definatly would stick about halfway up the pedal travel. It would never stop but it would slow down at a certain point, then, once it would get past that point, it would "snap" back up. What I ended up doing to solve it, was to properly adjust the clutch pedal. Jack's Transmissions has a good video tutorial to help you out. You might want to try this before tearing things apart.


Good luck,

Shawn

 

[unplugme71]

What? How do you deduce that he needs a new clutch? Nothing helpful in your post.


OP- Tim is probably right, since he probably know the driveline of these cars better than anyone. With that said, I had a similar issue with mine. It wasn't a weak "srping back" but it definatly would stick about halfway up the pedal travel. It would never stop but it would slow down at a certain point, then, once it would get past that point, it would "snap" back up. What I ended up doing to solve it, was to properly adjust the clutch pedal. Jack's Transmissions has a good video tutorial to help you out. You might want to try this before tearing things apart.


Good luck,

Shawn

I will give the adjustment a try. I have a feeling its probably it. Especially since my clutch seems to engage right as soon as I start letting up on the pedal. I remember now that it used to be a good 1-2 inches or so before engagement

 

[T is for TURBO]

Cool, let us know how it goes!

 

[twicks69]

I have not disassembled anything, but I'm hoping that there are no internal leaks considering they are brand new (<50 miles)

It doesn't matter if they are new or not; sometimes the cylinder volume doesn't fully fill upon initial installation due to the user not knowing how to properly fill, bleed and adjust our clutch hydraulic assembly; and that definitely includes the dealership technicians. As well, it is very common for the inner seal to have an imperfection in it causing a failure almost immediately, or a burr in the cylinder bore or on the piston bore causing a potential failure of the seal or a pressure loss issue. On top of all those things, it can also be a cracked or damaged pressure plate causing issues as I have seen that several times before. The pressure plate diaphragm spring can be cracked, the release straps could be damaged, or the diaphragm spring can be worn out causing clutch release issues or slippage issues. In this circumstance though, I still strongly feel that it is your clutch hydraulics that is your current problem with ghost pedal issues.

If possible, get your hands on a vacuum bleeder and reverse bleed the system drawing the fluid from a container and tube THROUGH the slave cylinder bleeder valve with your vacuum source being attached to your master cylinder reservoir. This way you can draw any air upwards as well as filling the slave cylinder volume without any issues. Then, adjust your master cylinder rod away from the firewall until you have 100% piston throw of the master cylinder to fill the bore of the master cylinder with fluid. Once it has been vacuum bled, refilled, adjusted and fluid level topped off, then seal the system, pressurize the system by depressing the pedal several times checking your fluid volume again, then adjusting the clutch master cylinder rod towards the firewall until you have complete disengagement of the clutch assembly.

Also while you are down there, check your pedal box assembly for worn bushings, damaged clutch pedal assembly, and leakage.

If you are still having issues after this, then check your clutch hydraulic lines and fittings from the master to the slave for leakage/damage/etc., and if those are good, fully disassemble, clean, inspect and repair/rebuild your clutch master cylinder and slave cylinder with OEM rebuild kits.

If none of this fixes your problem, pull the transmission and confirm that the clutch assembly, clutch fork, TOB, clip, pivot ball, etc. are all in proper working order without any slop or damage. Check for crank endplay while you are down there.

 

[turboglenn]

RRE covers this too, saying that just having liught pressure from your footon the pedal will let the flu9id leak past the seal since you're not pushing agaisn't it with force (like when resting foot on it whle driving which is a bad habbit) because there's no pressure to force the seal out agaisn't the cylider and therefore it goes to the floor and does ### you're saying

look up road race engineering 2g ghost pedal on google

 

[unplugme71]

RRE covers this too, saying that just having liught pressure from your footon the pedal will let the flu9id leak past the seal since you're not pushing agaisn't it with force (like when resting foot on it whle driving which is a bad habbit) because there's no pressure to force the seal out agaisn't the cylider and therefore it goes to the floor and does ### you're saying

look up road race engineering 2g ghost pedal on google

I never got into the habit of resting my foot on the clutch pedal so I'm okay there. The clutch was fine before replacing the master cylinder, so I'm guessing its just hydraulics.

Cool, let us know how it goes!

I'm going to try and do it today if it ever stops raining. Otherwise hopefully get it done sometime this weekend. I'll let you know the results.

It doesn't matter if they are new or not; sometimes the cylinder volume doesn't fully fill upon initial installation due to the user not knowing how to properly fill, bleed and adjust our clutch hydraulic assembly; and that definitely includes the dealership technicians. As well, it is very common for the inner seal to have an imperfection in it causing a failure almost immediately, or a burr in the cylinder bore or on the piston bore causing a potential failure of the seal or a pressure loss issue. On top of all those things, it can also be a cracked or damaged pressure plate causing issues as I have seen that several times before. The pressure plate diaphragm spring can be cracked, the release straps could be damaged, or the diaphragm spring can be worn out causing clutch release issues or slippage issues. In this circumstance though, I still strongly feel that it is your clutch hydraulics that is your current problem with ghost pedal issues.

If possible, get your hands on a vacuum bleeder and reverse bleed the system drawing the fluid from a container and tube THROUGH the slave cylinder bleeder valve with your vacuum source being attached to your master cylinder reservoir. This way you can draw any air upwards as well as filling the slave cylinder volume without any issues. Then, adjust your master cylinder rod away from the firewall until you have 100% piston throw of the master cylinder to fill the bore of the master cylinder with fluid. Once it has been vacuum bled, refilled, adjusted and fluid level topped off, then seal the system, pressurize the system by depressing the pedal several times checking your fluid volume again, then adjusting the clutch master cylinder rod towards the firewall until you have complete disengagement of the clutch assembly.

Also while you are down there, check your pedal box assembly for worn bushings, damaged clutch pedal assembly, and leakage.

If you are still having issues after this, then check your clutch hydraulic lines and fittings from the master to the slave for leakage/damage/etc., and if those are good, fully disassemble, clean, inspect and repair/rebuild your clutch master cylinder and slave cylinder with OEM rebuild kits.

If none of this fixes your problem, pull the transmission and confirm that the clutch assembly, clutch fork, TOB, clip, pivot ball, etc. are all in proper working order without any slop or damage. Check for crank endplay while you are down there.

I've had 3 shops, and myself, verify there is no air in the lines. I'll adjust the rod and see if that solves the problem before following the steps you mentioned. Hopefully there hasn't been any internal damage from driving thus far.

 

[T is for TURBO]

Ever get this figured out?