The Mystery of the Vanishing Clutch Fluid

[jehu]

A couple of weeks ago my clutch pedal suddenly became very soft I checked the reservoir of clutch fluid it was completely empty I added to fall and drove for a few days and checked it again it was about a quarter empty I refilled it and it has not dropped again at all in a couple days I thought I saw some oil flui A couple of weeks ago my clutch pedal suddenly became very soft I checked the reservoir of clutch fluid it was completely empty I added to full intro for a few days and checked it again it was about a quarter empty I refilled it and it has not dropped again at all since.

I did have a small stain right about center of the vehicle right around the position of the firewall I would say roughly on my pavement where I park but I haven’t seen that continue to appear

I had a clutch hose and his slave cylinder replaced a couple of months ago while I slave cylinder where in to a point where the seals allow for more fluid to be drawn into the system or perhaps begin to escape into the area of the clutch? Where was my fluid going if it’s not pouring out of the car and why isn’t it still escaping after it lost all that volume?

[Old525i]

Check the clutch master cylinder under your dash.

[south42]

I would check to see if your carpet is getting dripped on. I had this happen where the master was leaking and ruined the carpet.

Andy

[jehu]

No evidence whatsoever of any clutch fluid leaking from the master cylinder

[AHenry014]

If its not in your carpet, and its not leaving an obvious stain on the ground, then its gotta be in the bellhousing. Id suspect slave cylinder leaking. Its a pressure energized seal, so if a small piece of junk got stuck in there, it will leak when actuated until it gets pushed out, then the damage made to the seal and cylinder would likely cause a slow leak. Id find it hard to believe that it consumed a whole clutch fluid res without making a spot in your driveway, but it could be soaking into the clutch dust in the bellhousing, or your clutch disc.....

On second thought, check for any leaks at the firewall. Theres a bit of sound deadening there that may be absorbing the fluid.

[jehu]

So I have two spaces side by side. There is evidence of hydraulic fluid as I described right around where the rear bell housing would be. I have not seen it remain wet so it doesn't seem like a heavy ongoing leak. I checked the reservoir again yesterday and it had NOT dropped at all since the last fill a few days ago. The pedal offers firm resistance when depressing but I have felt firmer and its only a few months old itself. I know there are holes in the bell housing from which clutch fluid could drain and when I get it up on a lift I'll check them to see if anything appears to have drained from them. I couldn't imagine there is any wearing in other that would allow for additional capacity after the original fill when it was replaced . That piston seal would be the only location from where fluid could escape... the clutch hose and slave hard line I am told are not going to just loosen and leak. I suppose the idea that the old clutch hose shed some crap into the system is plausible.

If its not in your carpet, and its not leaving an obvious stain on the ground, then its gotta be in the bellhousing. Id suspect slave cylinder leaking. Its a pressure energized seal, so if a small piece of junk got stuck in there, it will leak when actuated until it gets pushed out, then the damage made to the seal and cylinder would likely cause a slow leak. Id find it hard to believe that it consumed a whole clutch fluid res without making a spot in your driveway, but it could be soaking into the clutch dust in the bellhousing, or your clutch disc.....

On second thought, check for any leaks at the firewall. Theres a bit of sound deadening there that may be absorbing the fluid.

[ross1]

Does yours have a discreet reservoir for the clutch?
I thought it shared with the brakes. The clutch take off port being higher so that any clutch hydro failure will not impact brakes. If completely empty the brake system would be suspect
The padding on the covering over the pedals could absorb a lot of liquid if the clutch master were leaking

[jehu]

I'll post pics of the clutch pedal/master area.. it doesn't appear from what is visible to me there is any evidence fluid has or is escaping that unit. There is a small cylindrical clutch fluid reservoir next to the power steering res so this doesn't share with the brakes.

Does yours have a discreet reservoir for the clutch?
I thought it shared with the brakes. The clutch take off port being higher so that any clutch hydro failure will not impact brakes. If completely empty the brake system would be suspect
The padding on the covering over the pedals could absorb a lot of liquid if the clutch master were leaking

[jehu]

Video of the items in question

https://youtu.be/WR6FF6UIbh0

[jehu]

this issue returned today after five days of stability without loss of fluid.

Pedal went down and didn't come all the way back up. I pumped it a few times and it came up . Reservoir was down half. Over the next few hours I had to add a bout a third three different times and saw fluid on the ground after parking


I did feel some fluid at the base of the res. I did not install it and am unaware of the type of connection this fitment uses.. the fluid could just be from sloppy filling..

Only real difference is its a good bit below freezing today a lot colder than its been.. Is this res/clutch hose fitment possibly leaking?

[Honolulu]

It's susceptible to a leak at any mechanical joint or fitting. Given as much as you're leaking, if you get down under you should see wetness that will lead you to the source of the leak.

There's another thing you can do: put some newspaper under the car and weight it down so it stays in place. Next day, there may be a spot on it. The dripping point (not necessarily the point from which it's leaking) will be directly above the spot.

[jehu]

Took it over to a Valvoline oil change shop to have them look it over... they say its leaking out the Bell Housing drain holes so its the slave seal. Have one going in tomorrow.. the idea about the clutch hose failure leaving rubber bits in the system I guess was probably right unless I just got a POS part. It was installed only a few months ago so i was reluctant to consider it. I'll just reiterate I still live at a Condo complex so I have nowhere to store tools like jacks and stands and just hadn't had the time to get under it till today.

It's susceptible to a leak at any mechanical joint or fitting. Given as much as you're leaking, if you get down under you should see wetness that will lead you to the source of the leak.

There's another thing you can do: put some newspaper under the car and weight it down so it stays in place. Next day, there may be a spot on it. The dripping point (not necessarily the point from which it's leaking) will be directly above the spot.