PSD flush using hammer; still need help
 

I have successfully bled the PSD accumulator and magnetic locking valve. DONE! moving on, bleeding the slave,
and have read and reread factory manuals, and the Ott write up on bleeding without hammer and am still lost....
I want to continue with the hammer and learn how to do this properly with the KTS 300.

the hammer has 2 PSD functions: 1.) bleed and 2.) check transverse lock: within the transverse lock prompt, there is
pressure build up (and the ability to control the pulses), and pressure reduction.

do I use bleed on the hammer to bleed the slave or transverse lock and use pulse control to bleed?

thanks in advance

After bleeding the pump and accumulator connect your bleeder catch bottle to the bleed screw on the slave cylinder. Be sure to keep fluid in the PSD reservoir through the whole bleed process as it will go empty pretty quick. With the ignition in the RUN position, crack open the bleed screw on the slave and start the "Bleed" routine on the Hammer. The Hammer will pulse the transverse lock valve and let fluid flow from the accumulator to the slave cylinder. If the pressure in the accumulator falls enough the pressure switch will turn on the pump to refill the accumulator. Let the bleed routine run until the fluid is clean and bubble-free coming out of the bleed nipple. With the bleed routine still running close the bleed nipple on the slave. Then tell the Hammer to stop the bleed routine. When you tell the Hammer to stop the bleed routine it will ask if you want to initiate "Pressure Reduction." Tell the Hammer to execute the pressure reduction. Disconnect everything and your done.

The "Check Transverse Lock" function allows you to manually pulse the lock solenoid valve as part of checking the setup of the LSD unit inside the diff. Basically the test is to actuate the valve a certain number of pulses, then check the torque required to turn one of the rear wheels. Too little torque means the clutch pack and pivot arm isn't set up correctly or the clutches are worn out.

Mike

Mike: you are the man! I have been searching for this info for a few weeks with no luck!

system is all bled, and finally I can put this job in the history books! thanks again!

FMI: could I have used the hammer to bleed the accumulator? the WSM instructions do not mention
using the hammer for that procedure, but say to pulse the pump manually......

No problem. WSM Section 39 page 206i. You don't need the Hammer to bleed the pump or the accumulator. The only thing controlling the pump is the pressure switch. Once you release the pressure in the lock solenoid via the bleeder on the top of the valve the pressure switch will turn the pump on as long as the ignition is on. The Hammer (or the alternate non-hammer method) simply cycles the lock solenoid valve to allow fluid pressure from the accumulator to flow to the slave cylinder. The lock solenoid valve is a pretty ingenious unit. Full voltage (+12VDC) moves the spool in the lock solenoid valve full travel to allow flow from the accumulator to the salve cylinder. A lower voltage signal (Pressure Reduction) moves the spool in the lock solenoid valve through partial travel to allow return flow from the slave back to the accumulator or the reservoir (can't remember which.)

Mike

There is a manual procedure contained within Jim Moorehouse's Technical CDs

the WSM instruction call for a pressure bleeder to be used; doesn't seem like its
a necessity? perhaps the bleeder's main purpose would be to keep the fluid topped up?

thoughts?

I didn't achieve good result until I used a pressure bleeder. Gravity just didn't seem good enough. And this is how I fill the reservoir.https://cimg6.ibsrv.net/gimg/rennlis...00e80585d5.jpg

hey kevin and community,

couldn't leave well enough alone, and decided to go back and pressure bleed my PSD. Later model reservoirs
have a vent tube, so when I pressurize the system, fluid comes out of that line.

not sure I can pressure bleed with this vent line????

Yeah, some have it in the cap, some on the body. I would source a vacuum cap at you local auto parts store. They come in assorted sizes.

mine is on the body

Mine is in the cap; regardless, if the system uses brake fluid and brake fluid is hygroscopic, is this not conducive to introducing moisture to the system? I assume that very small amounts of fluid are introduced to the pump, if ever, so that minimizes any contamination, but still.

The two times I have flushed this '93, the fluid coming out of the bleeders was slightly discolored, and the fluid in the res looked clear.

Sometimes I think Porsche designs these systems just to keep people like me, who have a limited understanding of physics, awake at night. Anybody else?

I agree Steve: why use a vent at all? there is no built up pressure, and the max line on the resv is far below the cap.

Posted message in the wrong thread somehow. Sorry. I deleted it