wdonovan

OK. Can't quite find out from svc manual, parts diag or owners man...

Looks like brakes and clutch share the same reservoir. Svc manual does not say to bleed the clutch when replacing brake fluid. My Lotus has a tanden cylinder that shares the reservoir and its procedure (like common sense would indicate) is to bleed the clutch to flush it when changing brake fluid. I see that bleeding the clutch is much more involved than doing the brakes. So... because of the extra work, does Porsche recommend ignoring the old, dirty, damp brake fluid in the clutch system? Or what? Anyone have a handle on this? Oh and keep in mind that I use SRF which ain't cheap so solutions that waste a quart or 2 aren't an option.

extanker

i would flush the clutch slave too if it was me. i think it would require less than a pint to do the clutch after the brake flush.

meteor10

Yes, I was wondering about this as well, anyone have a handle on this? Is there a tutorial somewhere?

Spokayman

Here is one.
http://www.planet-9.com/reviews/serv...er-cpage2.html

Haven't done it yet myself, but intend to sometime this driving season.

meteor10

Thanks for the link, doesn't look too difficult.

wdonovan

Odd that FSM does not mention it in brake flush procedure.

BE455

It isn't "difficult" but you need to be a contortionist to reach the bleed screw. Plus, likelihood of spilling some fluid is decent (getting the wrench on with the tube in place is tough). But agree, it's worth doing periodically.

Macster

Regarding the question of the newer cars, or even the older cars like my 2002 Boxster, without digging out my references I can't tell you specifically what Porsche recommends, but I can tell you that my experience is letting the brake/clutch fluid bleed go can affect clutch operation.

Sometime last year it was becoming harder and harder to move the car off from a stop smoothly. This had never been a problem before. Shifting became less smooth. Buttery smooth shifting has been a mainstay with my Boxster over the years but every shift felt like I was not pushing the clutch pedal down far enough.

At first I thought I was just getting sloppy and made a mental note to be sure to fully depress the clutch pedal. Shifting didn't improve. At the same time I paid closer attention to my clutch work when pulling away from a stop light. Take offs were not really any better in spite of my increased focus.

With the clutch and tranny being original and withbig miles (est. around 275K at the time) on them both I figured the clutch and tranny were going out. The transmission fluid was reasonably fresh, fresh enough to not warrant changing.

I was at the dealer and talking about this behavior with the service manager and of course brake/clutch fluid came up. I had thought both the brake and clutch fluid had been flushed/bled when I had the car in a few months prior for new front brakes.

The SM looked up the ticket and said "no" I had not asked for any fluid service at the time the brakes were done. I think I had meant to but it slipped my mind.

The SM went back in time and the last brake/clutch fluid service had been done a bit over 2.5 years earlier.

Before throwing a new clutch at the behavior I booked the car in for a brake and clutch fluid flush/bleed.

When I got the car back the clutch behavior and shifting action were both much improved, "like new" again.

While braking action/behavior never gave any signs of the brake fluid needing changing the clutch action which in turn affected shifting sure did although at the time I didn't connect the behavior with the fluid's age.

I'm pretty sure Porsche calls for a 2 year brake fluid flush/bleed and if it doesn't specify the clutch system be done at the same time (it probably does somewhere I'm just not willing to get up and go leafing through my printed references) my recommendation would be to have the clutch system flushed/bled at the same time as the brake system.

Marine Blue

Thanks for posting the how to link! I was just getting ready to do my two year flush of the brak system and was wondering if the clutch uses hydraulics to actuate. I will add this to the list.

For reference, on older Porsches the clutch hydraulics had steel internals and if you didn't flush the brake fluid regularly the internals corroded as moisture built up in the fluid. Poorly maintained clutch hydraulics leaked and or vibrated slightly during actuation.

wdonovan

@Macster - What you describe sounds more likely a small amount of air in the clutch lines than the effects of old fluid. I think you would never even feel it in a hydraulic clutch because there is no positive stop (mechanical lockup) like there is in a brake system.

@Spokayman - Thanks for the link. This method actually sounds more humane to the mechanic than the one spelled out in the Porsche FSM where they have you hang on to the clutch pedal for dear life and depress it while counting to 30 then counting to 90 to drain as much $90 / quart SRF into the puke can as you can manage. Oh and I think there is a Porsche special divining rod tool required. I am going to try it your way rather than the Porsche way.

Marine Blue

I just finished the brake/clutch flush and I'm glad I did. Lots of white debris in the line and the clutch actually had some dark bits in it. It makes me wonder if the dealer actually did a proper flush two years ago or if they simply did the front calipers and called it good. I say this because the front calipers didn't have as much debris as the rears.

It's also worth noting that bleeding the clutch is a pain in the butt. The nipple is nearly impossible to turn with any wrench and the only way I was able to loosen it was with a 11mm socket. You'll want to barely crack it and then turn it with your fingers the rest of the way. Reverse procedure to stop the fluid.

Dave in Chicago

A belated thanks to rennlisters who posted this back a ways... I just finished Oil/Filter, Pads/Sensors, Brake/Clutch Bleed excercise on my '05 Boxster S. All went very well, oil analysis is peachy, hardest part was getting the care carefully up onto jack stands.

Highly recommend the use of the Motive Power Bleeder. My kids used to use it to bleed the 944 when they were small. Works just as nicely on fancy 987 brakes :-) Consumed about a liter of fluid to do all four corners (2 screws each) plus clutch.

Dave

'05 987S
'92 968 SP3
'88 944 NA (gone)