Car guys: funky clutch behavior?

[Basher]

So I trained to work on bikes many moons ago, and at the time cable clutches were still the norm on most bikes I worked with (sportbikes). Thus, hydraulic clutch behavior is a little foreign to me, but today our ‘08 Honda Civic SI (which is dying at an ever accelerating rate) threw me a new one.

If you slowly press the pedal in, there’s no resistance whatsoever, and the pedal will remain bottomed out on the floor (you have to use your foot to pull it back up, where it will then stay). If you press it rapidly, it seems to function normally and hold pressure.

WTH is going on here? I would expect a failing CMC or CSC to gradually lose pressure if the seal was leaking, but as noted above, if I press the pedal in quickly and hold it down, it holds pressure fine and I can shift normally. But if I press the pedal down slowly (as if to slowly engage/disengage or slip the clutch a little), it goes completely dead and stays that way until returned to the fully disengaged/up position and then it’s fine again if you’re quick about applying it.

I’ll likely need to just take it in (garage is a mess and I don’t have time for this thing to be down for multiple days if I hit a delay doing it myself), but any ideas what’s going on here?

 

[Lpherr]

Have you checked for leaks? Look under the dash at firewall. The rear seal in master is common, as is the inner seal on the slave.
Both cylinders are inexpensive, and the only components besides the line between them.

 

[Nazgul]

Bad master cylinder. The cups/seals are shot.

Don

 

[Jaybird1980]

So I trained to work on bikes many moons ago, and at the time cable clutches were still the norm on most bikes I worked with (sportbikes). Thus, hydraulic clutch behavior is a little foreign to me, but today our ‘08 Honda Civic SI (which is dying at an ever accelerating rate) threw me a new one.

If you slowly press the pedal in, there’s no resistance whatsoever, and the pedal will remain bottomed out on the floor (you have to use your foot to pull it back up, where it will then stay). If you press it rapidly, it seems to function normally and hold pressure.

WTH is going on here? I would expect a failing CMC or CSC to gradually lose pressure if the seal was leaking, but as noted above, if I press the pedal in quickly and hold it down, it holds pressure fine and I can shift normally. But if I press the pedal down slowly (as if to slowly engage/disengage or slip the clutch a little), it goes completely dead and stays that way until returned to the fully disengaged/up position and then it’s fine again if you’re quick about applying it.

I’ll likely need to just take it in (garage is a mess and I don’t have time for this thing to be down for multiple days if I hit a delay doing it myself), but any ideas what’s going on here?

Yep, sounds like a blown seal. Look where your pedal goes into the MC under the dash and you will probably see wetness.

 

[DoggyDaddy]

Yep, sounds like a blown seal.

No, it's just a little ice cream!

 

[Jaybird1980]

No, it's just a little ice cream!

 

[thunderchicken]

I'm not familiar with that specific vehicle set up. But if it has a hydraulic throw out bearing it could be leaking too.
I agree with the others sounds like a hydraulic leak

 

[bwframe]

Don't think it's temp or quick freeze related do you?

I have a buddy say his Taco had all kinds of dash lights on after a sub-zero start a couple days ago.

 

[flightsimmer]

So you're not leaking fluid externally?
It sounds like the seal in the master cylinder is leaking under light pressure but when you push on it hard it pushes the seal against the wall and seals it.
That would probably mean the master cylinder.

 

[d.kaufman]

Either the clutch master cylinder or the slave cylinder

 

[bobzilla]

Either the clutch master cylinder or the slave cylinder

at this age replace them both.

 

[DeadeyeChrista'sdad]

View attachment 244751

 

[snapping turtle]

Either the clutch master cylinder or the slave cylinder

The new woke terms for these items would be the leader cylinder and the follower cylinder.

I will still call them master and slave but you may have to learn the new terms when all auto parts stores become ESG certified.

 

[Leo]

The new woke terms for these items would be the leader cylinder and the follower cylinder.

I will still call them master and slave but you may have to learn the new terms when all auto parts stores become ESG certified.

Please tell me you are joking.

I remember a push to stop calling electrical connectors male and female, but it never caught on.

 

[Lpherr]

The new woke terms for these items would be the leader cylinder and the follower cylinder.

I will still call them master and slave but you may have to learn the new terms when all auto parts stores become ESG certified.

Once that happens, only the elite of the elite will have personal vehicles and will no longer require auto part stores.
While us mere peons, beg for permission to participate in public transportation.

 

[Lpherr]

Please tell me you are joking.

I remember a push to stop calling electrical connectors male and female, but it never caught on.

They are now called "innies" and "outties".

 

[indyblue]

Please tell me you are joking.

I remember a push to stop calling electrical connectors male and female, but it never caught on.

In IT there are no longer master and slave drives or master/slave services.

Now it’s server/Client, or publisher/subscriber

 

[d.kaufman]

The new woke terms for these items would be the leader cylinder and the follower cylinder.

I will still call them master and slave but you may have to learn the new terms when all auto parts stores become ESG certified.

 

[Lpherr]

In IT there are no longer master and slave drives or master/slave services.

Now it’s server/Client, or publisher/subscriber

Hasn't those terms been used for many years, and not something new? I've heard them used for quite some time now.

I've never heard of a client being referred to as a slave.

 

[DoggyDaddy]

Hasn't those terms been used for many years, and not something new? I've heard them used for quite some time now.

I've never heard of a client being referred to as a slave.

I've heard them called client/server since at least the mid to late 90's. They were supposed to replace mainframe systems, but there are just some applications for which mainframes still rule.