Sometimes it's the craziest problems., Brake bleeding drama Options

[McMark]

I'm working on this 914s brake system, which is already a PITA, as we all know. This system just wouldn't bleed out. We capped all the outlets in the master and pumped the pedal until it was solid. Cool, added in the fronts and bled those until it was solid, added in the rears and it wouldn't bleed.

I pulled the limiting valve (aka proportioning) and swapped in another one, thinking maybe something was bad inside. Same problem.

At this point nothing is making sense. So in a 'hail Mary' move we pull the limiting valve again and use a spare brake hose to connect just the left rear. Bleed that, rock solid. Switch to the right.... same problem. Can't bleed it. (IMG:style_emoticons/default/blink.gif) WTF?

So we pulled the caliper intending to take it apart and check everything inside. as I was pulling it off, I thought maybe there was a dry patch inside the caliper. If it's not coated/wetted with fluid, the surface tension can create a bubble the won't move. I shook the caliper, dropped it in my ultrasonic bath (in a bag) and set it in my vibratory polisher (in the bag). It's back on the car now and it's finally getting close.

I've never had a single caliper be this stubborn, but from now on I'll be adding a little fluid and shaking the calipers before they go on the car. Tim here had a great idea as well, when we're done bench bleeding the master cylinder we'll hook up the calipers and bench bleed those as well, all before it goes on the car.

And people wonder why I hesitate when they ask, "How much is this going to cost?" Who could have known this was gonna happen. And it's a 914--seems like every project has some of this kinda thing. (IMG:style_emoticons/default/wacko.gif)

[r_towle]

adding the new 914 brake dance to the process, check...

Rich

[Stiffmeister]

adding the new 914 brake dance to the process, check...

Rich

Had my own little Hell. Tried preasure, tried vacum (mitivac?) Pedalmaraton. Nothing worked. Finaly i put preasure in the brakeoil tank and blead between pipe and hose on all corners. Rocksolid pedal.