Clutch puzzler

[ybt502r]

Here's a story of my clutch hydraulics, and I don't understand it, but I need to point out that this is a repeatable condition. Perhaps someone can clue me in.

I've a '77 UK-sourced SIII. Last summer, my clutch master started leaking, so I replaced it and refurbished the slave. I would have replaced the slave, but the new slave didn't quite fit, so I used its internals to rebuild my existing slave. After three months or so, my master started leaking again, and I replaced it one more time. That time, I also replaced the flexible hydraulic line connecting the two steel lines. Now, three months later, I'm losing clutch hydraulic fluid (DOT4 brake fluid) again. It does not appear to be the MC, and I can't really see evidence of where it is leaving the system. Here's where it gets tricky. When the MC fluid gets low, the clutch does not work well, and I realize it's low. So I top it off, but of course the clutch line must have some air in it now, and the clutch take up point is very low to the floor - but I can still shift fine. This goes on for a couple days with me checking the fluid daily. If and when I take the Rover to a car wash (in Alaska in the winter, the car wash usually includes an under body spray), the clutch goes back to working properly - though I need to top off the MC again. This will then work fine until some future time when enough fluid leaks out that the process repeats itself.

This has happened three times, and this third time I purposely went to a car wash to see if it self-healed, and it did. I'm wondering if I have some sort of intermittent leak (maybe triggered by the cold as it's been a bit cold lately, though the Rover is garaged) down low (the slave? the flexible line?), and thus it sort of "self-bleeds" the air out of the system. That really seems far-fetched, but I don't have any better ideas. Does anyone else? I sure don't want to pull the wing again to replace the MC a third time, especially if I'm not even sure that is the problem.

[Opabob]

I have similar issues. I've got both wings off and am looking at the master and the slave. I don't see any leaks, so it is a mystery where the fluid is going. Not too wild about replacing the cylinders if they don't need that. Curious to hear what others say.


Sent from my iPhone using Tapatalk

[SafeAirOne]

Why didn't the new slave fit? Very odd since it's a dead simple system in the SIII.

Where is the fluid going? Find the fluid and find the problem. Really, there's only 3 possibilities: The MC, the slave or the flex line, presuming the hard lines are intact and tight.

[ybt502r]

Mark, I agree and have traced the lines and will do so again when the sun eventually comes out. Its a slow leak and somewhat intermittent. It could be pooling where the MC is and has not started to run down the bulkhead like it eventually did before. The strange part is why it seems to heal itself (in terms of the clutch take up point, which I take to be air in the line from pulling it in at the MC) from whatever the car wash seems to trigger. If I can figure that out, then perhaps I can find what to fix. That is what makes me think it's with the slave or something low, as the MC never sees anything from an underbody spray.

The new slave "didn't quite fit"; I feel I could have forced it, but instead I went the simple way. It had to do with the bolt alignment I recall. I know it is a simple system, which is why this odd behavior has me confused.

[ignotus]

You could have fluid leaking past the piston in the slave and into the flywheel housing assy, then if your wading plug is out it comes out the hole in the bottom front. I like your air bubble self bleeding theory but it doesn't explain the carwash "fix", could the slave be loose and the spray knocks it back into position? I know I'm reaching, but there is nothing down there, could be a red herring and maybe the pivots on the pedal free up, another thing to check is if the pedal/MC pushrod connection is tight. shrug

[ybt502r]

I think you might have something there. I purposely parked the Rover in a warm underground garage after a trip. I made sure that the cement under it was clean and spot-free. After about 3 hrs, I came back to find some hydraulic fluid pretty much right in the middle of the vehicle. I got underneath it to see if I could trace it, and the closest point I could find was the center brace and the bell housing (with the wading plug out). I did not realize that the slave could leak into the housing from the slave, but it now looks like that's the first place to check. I did double check again this weekend all the other fittings; they are good and dry. I'm not sure about the MC just yet, but since I've had two develop leaks in the last 6 months, I don't know if I'm looking at new stuff or residual stuff. It does not look new to my eye.

If it's leaking at the slave (the bolts are solid and the bleed nipple is dry), then it must be past the piston and into the flywheel, which is why I can't see the hydraulic fluid anywhere on the truck. Since i rebuilt the old slave with the new slave's parts, there's probably a good chance I didn't get it quite right too. I'm going to start there next. Thanks for helping point me in hopefully the right direction.

[ybt502r]

Here's the follow up, courtesy of Ed Angel who finally sorted out the issue. The leak was in the o-ring of the slave in that it was too loose (too big). It would work when driving as I guess the pressure application would help it seal, but when the Rover was parked and cooled down, the clutch fluid would then leak out past the slave piston. That also explains why the car wash (with warm water) would seem to help too, as it would swell everything up and get a good seal again. Even though it all looked good and it was a rebuilt slave cylinder, it was never going to work. So the slave was replaced, the threads filed down a bit (so it could be hooked up, which was the problem apparently with the first new slave I tried), and it all bolted together nice and tight. I guess either the rebuild kit didn't quite match or the old slave had just worn too far.