cobalt

If you track it once a year for street driving once every two is adequate.

Beezztie

Hmm, I cannot find anything similar on my '90 C4 at that location? I did find the below on the right side:

Is that the same? (does look a bit different?)

Spokes

That isn't the slave. That looks like the traverse lock. Slave is high on the transmission.

Harry Apps

Take a look at Ricardo's Post 2.

Beezztie

Got it, wasn't looking high enough, silly me.. Thanks!

HiWind

damn my new to me C4 is proving hard at every turn ...

just went thru 5 quarts on the bleed per the advice above:
- pedals good, lots of schmoo and bubbles then all went clear
- turn on the car and .... pedals soft (clutch to the floor, brake way too soft.)

Did this twice hence the 5L ... pooped and stumped.

I followed Ricardo/Adrians Book exactly save for the poor mans (no hammers in service near me) approach Darrell mentioned above to the two gbox mounted units (ie other than the clutch slave).
I did not get much schmoo or bubbles from the two locks but I bled them one at a time .. maybe that's the problem?

Also when draining the fully charged accumulator there seems to be an internal cutoff valve as the main pressure comes out fast but after a few seconds it sort clicks closed rather than running down slowly as pressure dissipates. Either way there were no bubbles there either after a couple bleeds and I bled at least 250ml per nipple or 10 sec of clear bubbless liquid per nipple.

Could be master or slave but pedals were fine before I started the refurb .. so beside draining pretty completely (caliper refurb etc...) nothings changed ITR.

As always thanks for throwing out any ideas .. ordering the handheld device tonight but the fact that the pedals go hard then soften on the ignition (ie pump activation) means I must be doing something slightly wrong from a bleed order perspective ... must the accum and abs be done first then the calipers then the clutch then the locks .. that's been my process.

A914MAN

I've always employed a home made, one man pressure bleeder. I modified a reservoir cap by adding a tire valve. I use a clip on air chuck, and two air regulators (one at the compressor and one near the car) to make sure I don't over pressurize the system. I set the air pressure at about 10psi, fill up the reservoir all the way and then bleed in the recommended sequence; taking car not to let the reservoir get too low.

Basically you are using air pressure on top of the brake fluid to push new fluid through the system.

I use a box end wrench that I put on the bleeder before the hose, so you go even one step beyond a flare wrench.

Like the garden sprayer pressure bleeder, you never have to pump the pedal, and it's worked on every Porsche I've owned, 914, 964, and Boxster, although the 964 and Boxster were both Tip. I don't see why this wouldn't work fine with the clutch too.

HiWind

^^ yes thanks A924 ... as discussed at length above the 964 C4 requires a pressure bleeder (motive or like yours) and the 'traditional' method of foot pumping is specifically noted to not work with the complex 964 C4 setup (off the 959, very different from the simplified version in the later 993).

DWS964

Just revisited this thread. I haven't been on the 964 forum in ages, although I still have the 92 C4. I just went through the full procedure a couple months ago prior to tracking my C4 for the first time in 9 years.
A couple thoughts and suggestions:
Do the accumulator and PDAS block purges (per Adrian and shop manual) first. These purges use a LOT of fluid and its a good way to to fully flush out the large volume of old fluid in the reservoir. Otherwise, you have to go through a LOT of fluid on the caliper bleeds to get to all clean/fresh fluid. But, be absolutely sure you do not let the reservoir get too low while purging the high pressure system - it is easy to do because you can go through a Lot of fluid. Don't ask me how I know. If you do, you will have to go through a Lot more fluid to get the high pressure circuit full. If there is air in the high pressure circuit, the pump will be Very noisy (probably is damaging it) until you get it clear. Plan to use a full liter of fluid, minimum, on the accumulator and block.
Also, I recall that with the hydraulic boosted system, you should NOT pump the pedal while the Motiv is attached to the reservoir or you can damage the master cylinder. One of the experts out there will know for sure.
Good luck.
BTW - the C4 was a HOOT back out on the track, not as fast as the other cars, but who cares.

dlpalumbo

HiWind,

The clutch fluid pickup in reservoir is much higher than you'd guess by a quick look at it. I tried a dry bleed at first and got air in system, peddle went to floor. Reverted to wet bleed and all is well. Bleed the bomb. I noticed no effect from a shutoff valve, but I made sure the bleeder pressure stayed at 20 psi. Make sure you do double bleed. First one you depressurize bomb with 20, or so, peddle pumps, unplug pump, and bleed. Second one, plug in pump, let it pressurize, unplug pump, then bleed. Make sure to hold onto hose as initial squirt will be forceful. This worked for me.
Good luck,
Dan

HiWind

thanks Dan .. will try the wet bleed (noticed one or 2 of the chambers in the reservoir can be very narrow and caught me out a couple times) and redo the accumulator as you suggest

John McM

I take it from the above that bleeding the above volumes from the various points all but ensures a full fluid change. Is that correct?

dlpalumbo

The numbers are correct as far as whats written in manual, however, I would think if you bleed one nipple at a wheel, the second will take much less as the line is already bled. So the split would not be 50/50 as suggested. I dont know how much the first nipple will take though. Also, the right rear should require more fluid than the left front. The 250 cc probably includes chamber in reservoir, which may be the largest part of the total.

I have never measured how much it takes but bled until color change. Someone who still has ATE blue could make definitive measurements.

John McM

I have marked up the Motive bottles, ready for use when my new fluid arrives.

John McM

I used 1.6 litres to bleed the calipers, clutch, accumulator and dual solenoid. Unfortunately I couldn’t finish the job as the PDT999 would not connect to the PDAS. I know the PTD999is working as it connected to the Motronics on this car and the PDAS on my other C4. I think I will have to use the switch method.

Btw the nasty fluid is from the clutch slave.