DanL993

Second time in two years now (two year intervals) and I get darkend liquid initially flowing to clearer as the newer fluid cycles through.

Is this of concern or normal? Is this any indication that seals or internals are starting to deteriorate?

stace

that's normal - and the point of flushing the system. there are a number of lines, o-rings, etc that with constant heating of the brake system during use, "pollute" if you will, the brake fluid. and brake fluid naturally absorbs moisture. that's why routine flushing is important. be sure to flush the whole system including the slave cylinder, each caliper, the booster pump (if a C4, turbo, etc).

Slow Guy

I suspect the main culprit is the rubber hose that goes from the hard line attached to the undercarriage to the slave cyl. itself, it's most likely about 15 years old. To me it's understandable it would be decaying and causing the fluid to darken.

Steve Weiner-Rennsport Systems

Spot-on!!!!

Brake/clutch fluids are hygroscopic and darken as they absorb moisture over time. When moisture levels reach 4-6%, the system should be flushed with new fluid.

I have an expensive Leica instrument made specifically for measuring moisture content and the fluid starts looking more like root beer when you see 4%.

Good maintenance extends the life of master and slave cylinders.

JasonAndreas

A brand new OE hose and slave cylinder will also darken brand new ATE fluid in only a few days time... (it was maybe ~5 days in my case)

DanL993

OK guys, thanks. I do the maintenance regularly but can't find any citation in the fairly complete maintenance records that this was ever done prior to two years ago!! I was concerned that only the clutch fluid was dark (root beer color is right on Steve!). I will press on now. Thanks again to all.

NC TRACKRAT

The clutch slave cyl. is the lowest part of the system, so the crud and moisture naturally winds up there.

Slow Guy

^^^ I think your clutch slave is riding mighty low.

DanL993

Yeah! Mine sits on top of the transmission, well above the level of any of the calipers. In fact I balanced a work light on top of my left rear caliper to shine upwards on the job. Drained the clutch cylinder last BTW.