79 300TD I redid the brakes a couple weeks ago, new rear calipers, bled out all old fluid, etc. Worked really fine.
A few days ago, no brake boost, or rather, a bit of boost at first pedal push then nothing), slow turning off. Checked all the vac lines, looked OK. Drove it again today, same problems. So put the vac meter on the line, getting about 22in vac, OK, push the brake pedal, goes down to like 5in or so, really low, and no boost, builds back slowly. So pumped down the booster with the mity vac, same thing (which maybe I would expect since no constant vac on it). (This says the booster is probably OK, not leaking vac? Or maybe since that check valve is in there it could be leaking down in the booster? The check valve is stuck in the hose really tightly, can't get it out with destroying it so hard to test the booster straightaway.) Put the vac gauge on with engine running, getting 22in vac, push the brake, goes down low again but does not build up, then vac needle going crazy bouncing between vac and pressure. Whussup wif dat? Took off the gauge and sho nuff you can feel huffing/puffing and no constant suction. Weird, it just did that. Maybe doing it before too. So now I'm thinking the vac pump must be acting up again (I have rebuilt it twice now). but since I was getting a good vac there for awhile I am thinking those little one way valves inside the vac pump must be clogged or inop or something? That sound like a good diagnosis? Think if I suck on each hose coming right from the pump, or maybe blow some air into them, that might do something (useful)? I am thinking the booster is probably OK, must be there in the vac pump somewhere. There is a bit of oil in the lines, I guess maybe that could be clogging things up. I am reluctant to take the vac pump off/apart again, though I am pretty good at it by now. Any thoughts? --R _______________________________________ http://www.okiebenz.com For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
