Clutch master cylinder

[nbristow01]

I need some expert help with a problem I am having. I posted earlier that my clutch pedal would randomly just lose pressure. May work fine 10 times, then number 11 it just has much less pressure and sinks to the floor and I can not shift. let it up, depress it and it is fine. I have never had a master cylinder go out so i am not sure what I am experiencing. The master and slave both have about 30k on them. I swapped to a 5 speed last late fall. The fluid is dark. I went ahead and bled the clutch master just in case it may be an air bubble stuck. Had same issue. Brakes work perfectly. My mechanic friend agreed with what one of my trolls said that the fluid is dark from oxidation, etc but is not what the issue is.

Just looking for a recommendation on what i should do next. Does this sound like a clutch master going out?

[tjones02]

Either one, the other or both the MC and slave are bleeding down. Pop the boot off the slave to see if there's fluid leaking. If there is no fluid leaking from the slave.... the MC is the culprit. BTDT many, many times and obviously not just on my own cars. If the MC is pushing fluid, the only place for the slave to leak is externally..... The clutch MC can bleed back internally (back into the reservoir) and or externally.

Obviously you should check the hose for leaks as well.... :b....

Cheers and HTH,

[TobyB]

Here's a loose rule-

if you're losing fluid and you don't know where, it's the slave.

If you're not losing fluid OR the inside of the pedal box is wet,

it's the master.

Fortunately both are cheap- if it was me, at the point that I change

the master I also change the slave and keep the old one as a spare.

t

[Guest Anonymous]

I need some expert help with a problem I am having. I posted earlier that my clutch pedal would randomly just lose pressure. May work fine 10 times, then number 11 it just has much less pressure and sinks to the floor and I can not shift. let it up, depress it and it is fine. I have never had a master cylinder go out so i am not sure what I am experiencing. The master and slave both have about 30k on them. I swapped to a 5 speed last late fall. The fluid is dark. I went ahead and bled the clutch master just in case it may be an air bubble stuck. Had same issue. Brakes work perfectly. My mechanic friend agreed with what one of my trolls said that the fluid is dark from oxidation, etc but is not what the issue is.

Just looking for a recommendation on what i should do next. Does this sound like a clutch master going out?

This is not a subject that requires "expert" help. This is clutch hydraulics 101. Plenty of info in the archives standard repair manuals on symptoms of failing master and slaves.

Ever have a brake master cylinder start to fail? Need to pump the pedal more than normal to maintain pressure? Same principals involved.

Dark fluid is not only an indication of oxidation, but color change can be suspended or dissolved particulates i.e, a tell tale sign that seals are wearing - as one might expect after substantial use. Hint: most of the seals tend to be black, just like the color of the fluid.

[nbristow01]

I need some expert help with a problem I am having. I posted earlier that my clutch pedal would randomly just lose pressure. May work fine 10 times, then number 11 it just has much less pressure and sinks to the floor and I can not shift. let it up, depress it and it is fine. I have never had a master cylinder go out so i am not sure what I am experiencing. The master and slave both have about 30k on them. I swapped to a 5 speed last late fall. The fluid is dark. I went ahead and bled the clutch master just in case it may be an air bubble stuck. Had same issue. Brakes work perfectly. My mechanic friend agreed with what one of my trolls said that the fluid is dark from oxidation, etc but is not what the issue is.

Just looking for a recommendation on what i should do next. Does this sound like a clutch master going out?

This is not a subject that requires "expert" help. This is clutch hydraulics 101. Plenty of info in the archives standard repair manuals on symptoms of failing master and slaves.

Ever have a brake master cylinder start to fail? Need to pump the pedal more than normal to maintain pressure? Same principals involved.

Dark fluid is not only an indication of oxidation, but color change can be suspended or dissolved particulates i.e, a tell tale sign that seals are wearing - as one might expect after substantial use. Hint: most of the seals tend to be black, just like the color of the fluid.

Thanks for the hydraulics 101. I guess maybe what i am seeing color wise could be the seal from the clutch MC. I guess it all points to just replace the MC and slave

[nbristow01]

Either one, the other or both the MC and slave are bleeding down. Pop the boot off the slave to see if there's fluid leaking. If there is no fluid leaking from the slave.... the MC is the culprit. BTDT many, many times and obviously not just on my own cars. If the MC is pushing fluid, the only place for the slave to leak is externally..... The clutch MC can bleed back internally (back into the reservoir) and or externally.

Obviously you should check the hose for leaks as well.... :b....

Cheers and HTH,

Thanks both Toby and Tom... that was the exact type or helpful response I was hoping for. I have never had a clutch or brake MC go out so I did not know if they just suddenly quite or tend to go out slowly. Since I have no loss of fluid and have no leaks anywhere I guess it maybe the MC is bleeding back internally and as Griffin pointed out that dark color may be due to the MC seal ending its serviceable life

[TobyB]

if they just suddenly quit or tend to go out slowly.

heh... yes, it can go either way.

t

[nbristow01]

Thanks all. I went ahead and ordered a new MC from BLUNT. Cheaper than a tow