1. If clutch fluid comes out of the clutch hydraulics system then obviously air will get in. Is there a for air to get in even if water is not leaking out?

  2. After bleeding the slave cylinder we forgot to top up the clutch fluid and drive the car for 20 minutes. Would this have caused air to get in?

  3. What if the clutch fluid was low though not empty, would that cause air to get in?

  4. When you bleed a slave cylinder, should you be seeing any fluid in the clutch container. If it returns there what does this mean?


1 Answer 1

  1. If you are topping up the hydraulics with water, you should drain it immediately, flush with hydraulic fluid, refill and bleed. 1a. Air can seep in past the cylinder seals in small amounts, which builds up over time. The more aged the seals become, the more air seeps in. So the seals need replacing at some time, although it is safer to replace the complete cylinders.

  2. Perhaps.

  3. Probably not.

  4. There should be hydraulic fluid in the reservoir at all times. When you bleed the clutch or brake system, some of the fluid is lost, so you should keep an eye on the reservoir and keep it topped up to the correct level.

  • I apologise I mean t clutch fluid and not water lol. Oct 8, 2020 at 20:39
  • I thought the 'water' might have been a lapse of typing not actual but I mentioned it in case. The reason it is bad is because it dissolves a certain amount of air and so it is compressible. But strangely, the hydraulic fluid used has an affinity for water and gradually adsorbs it, perhaps through the surface of the fluid in the reservoir, and this is one reason why the fluid should be drained and replaced at intervals anyway - it contains air that you can't bleed out because it is dissolved. Oct 8, 2020 at 20:52
  • Thank you for your reply. So you are saying air can get in even if fluid doesn’t leak out. So should I be able to visually see seal damage, how can I diagnose it since can’t see leaks? The bleeding definately helped car sounded better than it had for a year but problem came back soon afterwards. Oct 8, 2020 at 22:28
  • Wane you have misunderstood 4. My question was if you bleed it and have not topped up yet, should there no more fluid in the reservoir until you have added it. In my case, after the bleeding there was no fluid in the reservoir, we forgot to top it up and went for a drive and about to add fluid we saw some fluid already there which would mean the bleeding didn’t remove it all and it gets t push back to the reservoir. Is this normal or what does it mean? Thanks. Oct 9, 2020 at 8:06
  • Hydraulic oil expands with temperature so if you went for a drive that may be why some fluid was seen in the reservoir afterwards. It's a strange question: keep the fluid topped up. If you bleed say, the brakes, and they are still spongey, you need to change the fluid, and/or the cylinders. You are talking about the clutch, but I mention brakes because it is easier to feel the sponginess. Oct 9, 2020 at 8:34

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