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Running into some trouble trying to bleed my rear brakes and I've isolated the issue, but don't know how to resolve it. Hoping someone here more familiar with the PSM module might be able to help. Issue: I'm using a Motive bleeder and have good flow into the "H" (rear) input port of the ABS block, but I have no flow from either the HL (rear left) or HR (rear right) output ports of the ABS block. I know the PSM system doesn't have a mechanical proportioning valve, but could the system have electronically isolated the rear circuit? If so, any idea how I might reset it? That could be the wrong track... maybe I have a bad relay or solenoid.
1999 Boxster S Tiptronic 57K miles. Spent good part of the afternoon trying to get to the bottom of coolant loss from the expansion tank. Wife went to use the car yesterday and the red light started flashing, checked the expansion tank - empty. Took about 3 litres to refill. Today I went through a 'bleed' procedure. Pulled up a spring loaded clip on top of tank, slowly filled tank, remove a fuse B1 to effect some sort of valve - apparently only needed for tiptronic system bleeds, run engine up to 90 - used cooking thermometer into expansion tank, reving engine every few minuets. There was a visible flow. The tank spilled over when it hit about 90(when the stat opened?) then settled down fine.This process took about 40mins. Reset spring clip, refitted fuse(which stopped the instruments working whilst removed), closed tank lid and took car for a spin. After about 6 miles steady driving pulled over and checked tank level - all good. Did another 6 miles with a blast up to about 6K revs in 3rd. Got back home and pulled over. all good. Ticked over for a few mins fine. Did one more lap of the block and pulled over; a large gush of water came out of the top of the tank -about 2.5Ltrs on to the road. Back to square one. Is there something I'm doing wrong?
OK, I hope this does not result in someone calling me an idiot, but here is what I did: I just flushed my brake system in preparation for a DE, which I have done many times before. The old fluid was in good shape, and so it was nearly impossible to tell when the new fluid started. This time, using a pressure bleeder, I pushed most of the old fluid out of the reservoir before I started dumping new fluid into the thing so as to minimize the mixing. I may have actually pushed some air into the lines - I'm not sure - but I was not too concerned about that because I figured that the air bubbles, if present, would give me an indication of when I was getting to the new fluid. I then flushed two full 500 liter bottles of Motul RBF 600 through the system starting with the RR outside screw, then RR inside screw, then LR, then RF, then LF. There were some very small bubbles present, but I never did see any significant air bubbles come out of the system before I ran out of new fluid. I took the car for a drive, and I immediately noticed that the brake pedal travel was longer than it had previously been. Pumping the pedal did not make the pedal travel shorter. I would have expected the pedal to stiffen and the travel to get shorter if there was air in the system, but still, I was concerned that I had introduced air into the system, and that I had not gotten it all out. So I bought two more 500 liter bottles of Motul and I flushed most of that through the system, but I never did get any significant air bubbles to come out (there were a few micro bubbles). The brakes seem to work fine other than the longer pedal. I'm concerned that I may have introduced air into the system, and that the air may be somehow "stuck" in the ABS pump. I'm not sure if this can happen, especially since the ABS pump did not cycle at any time during the process. Have I screwed up my brake system? Thanks in advance. Mike