Author Topic: Water in the clutch hydraulics  (Read 1605 times)

Offline Gnomad42

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Water in the clutch hydraulics
« on: November 17, 2017, 11:43:25 PM »
On inspecting a suspected blown seal on the clutch slave cylinder, I found a mess.
- Crystals in the cylinder,
- corrosion on the piston, and
- water in the DOT4.

I have no idea how it got into the system, but I got a surprise when the fluid leaked out and the clutch stopped working!

Anyone else had this happen?
Gnomad42
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P.S> why can't I post a picture of the slave cylinder?
« Last Edit: November 17, 2017, 11:56:55 PM by Gnomad42 »
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Offline Gadget

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Re: Water in the clutch hydraulics
« Reply #1 on: November 18, 2017, 08:53:30 AM »
The water gets there because brake/ clutch fluids is hygroscopic.

Hygroscopic means it absorbs moisture from the air.

Initially it mixes with the fluid, but as it gets more concentrated, the water eventually pools.

If there are leaks in the seal on the master cylinder cover, the moisture is sucked in. Any air above the fluid dries out, which shrinks its volume, so more air is sucked in.

That's why it's important to change brake and clutch fluid at regular intervals.

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Offline Gnomad42

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Re: Water in the clutch hydraulics
« Reply #2 on: November 18, 2017, 08:55:36 AM »
The water gets there because brake/ clutch fluids is hygroscopic.

Hygroscopic means it absorbs moisture from the air.

Initially it mixes with the fluid, but as it gets more concentrated, the water eventually pools.

If there are leaks in the seal on the master cylinder cover, the moisture is sucked in. Any air above the fluid dries out, which shrinks its volume, so more air is sucked in.

That's why it's important to change brake and clutch fluid at regular intervals.

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Thanks Gadget. Good explanation & Great to know.

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Between two of us we are currently homing;
Honda ST1300 Pan European - 2004
Honda ST1100 Pan European - 2000
Honda NT650 Deauville - 2004
Honda CBF250 - 2006
Honda CBRR250 (MC19) 1980something
Suzuki LC250 Intruder.
Suzuki M50 Boulevard
Most running, sort of.