New rear PMB alloy calipers. Now no break pressure Options

[Downerman]

OK, OBVIOUSLY no negative to the calipers. Here's the deal..... removed the 911 rear calipers (well for that matter the entire swing arms) but I just let the brake fluid lines hang and drain into jars. Finally got my swing arms mods done and now putting on the new calipers. Filled the brake resevoir up and had all 4 wheels off the car. Used my handy dandy brake sucker pump and had fluid running to all four bleeders on the rear (2 each for a caliper) and then did the fronts. Had to refill a couple of times because I was pulling some darker fluid until it was clear. Went into the cab and hit the breaks. Nothing.... I mean NADA. Pumped like a 100 times to no avail.

RE-DID the entire process again. NADA and I mean nothing. So, I'm wondering if my master has gone south in this time line?? and why?? Seems the only logical answer at this point. Anyone have any ideas?

Dave

[wndsrfr]

OK, OBVIOUSLY no negative to the calipers. Here's the deal..... removed the 911 rear calipers (well for that matter the entire swing arms) but I just let the brake fluid lines hang and drain into jars. Finally got my swing arms mods done and now putting on the new calipers. Filled the brake resevoir up and had all 4 wheels off the car. Used my handy dandy brake sucker pump and had fluid running to all four bleeders on the rear (2 each for a caliper) and then did the fronts. Had to refill a couple of times because I was pulling some darker fluid until it was clear. Went into the cab and hit the breaks. Nothing.... I mean NADA. Pumped like a 100 times to no avail.

RE-DID the entire process again. NADA and I mean nothing. So, I'm wondering if my master has gone south in this time line?? and why?? Seems the only logical answer at this point. Anyone have any ideas?

Dave

Theres a procedure for "bench bleeding" a master cylinder.....sounds like you have air in there.

[Mblizzard]

If you go to the old open the bleeder and pump the pedal with no fluid movement, I would say it is the master cylinder.

Was the system open for any amount of time?

[Downerman]

Yes, maybe 3-4 weeks.

Dave

If you go to the old open the bleeder and pump the pedal with no fluid movement, I would say it is the master cylinder.

Was the system open for any amount of time?

[Downerman]

Found this.... same issue as mine using a "Sucker" bleeder.

[76-914]

Yep, bench bled time.

[Downerman]

Ok, bench bleed time. I've read some posts that have me so confussed it's not even funny. Is there a simple way to do this while the MC is in the car?


Dave

[Jeffs9146]

Just crack the lines at the MC. Make sure there is fluid.

[rgalla9146]

Ok, bench bleed time. I've read some posts that have me so confussed it's not even funny. Is there a simple way to do this while the MC is in the car?


Dave

Do the simple thing, get an assistant and bleed the whole system the old fashioned way.
In the future when you have to remove any caliper, wheel cylinder, hose or pipe from a working system push the brake pedal down about an inch and prop it in that position.
By doing this you will prevent the system from draining and you will simplify the bleeding procedure.

[Elliot Cannon]

If the system was dry for 3 to 4 weeks, the seals in the MC might have shrunk.

[Tbrown4x4]

If the M/C is old, sometimes rust and dirt settle to the bottom of the bore and when you bleed the brakes the cup seals can be damaged. If you bleed the brakes by pushing on the pedal, the cups are pushed past their normal range of travel and can run over this junk and tear the seals. Pressure bleeding is best, but not as simple.

The low position of the master cylinder in the 914 makes it harder to rid the system of air. Remember to always bleed the caliper farthest away from the M/C first, then continue in order to the closest caliper. Then do it again.

[Downerman]

Thanks everyone for the info. Yeah I started with Passenger rear, drivers rear, passenger front and drivers front. Bottom line though is I have brake fluid for days coming out clear and bubble free from every bleeder. Just NADA at the peddle. I have been scrambling to try and find a method of bleeding the master cylinder but nothing makes sense. If I don't have ANY pressure in the peddle will simply losening the nuts on the MC release the air? How could it if there's no pressure?

I'm losing my mind on this simple issue.

Dave

If the M/C is old, sometimes rust and dirt settle to the bottom of the bore and when you bleed the brakes the cup seals can be damaged. If you bleed the brakes by pushing on the pedal, the cups are pushed past their normal range of travel and can run over this junk and tear the seals. Pressure bleeding is best, but not as simple.

The low position of the master cylinder in the 914 makes it harder to rid the system of air. Remember to always bleed the caliper farthest away from the M/C first, then continue in order to the closest caliper. Then do it again.

[Jeffs9146]

By loosening the outlines on the MC and letting it gravity feed you will fill the MC with fluid. I use a pressure bleader and do the same thing starting with the MC and then each of the calipers one at a time until no more air comes out, filling the resevore often. Gravity can be used to slowly blead most of the air and then start pumping. Otherwise your MC is bad!

[Downerman]

Ok Jeff, I will try this in the morning. Thanks again. BTW.... born and raised in Stockton. My first Porsche was a 72 914 in 1977. Used to know all those back roads/levee's from Highway 4 to Highway 12. I remember when Discovery Bay was built in the middle of a asparagus field.... dang, starting to sound like my grandfather.

Dave

By loosening the outlines on the MC and letting it gravity feed you will fill the MC with fluid. I use a pressure bleader and do the same thing starting with the MC and then each of the calipers one at a time until no more air comes out, filling the resevore often. Gravity can be used to slowly blead most of the air and then start pumping. Otherwise your MC is bad!

[Downerman]

For those who care to know..... I bled the M/C to no avail. Purchased a new M/C and same issue. FINALLY listened to what Eric and PMB had said about my calipers being horizontal (Had to re-clock the hub housing because I took out 3/4" for 7" Fuchs to fit the car. Well, before I did anything I called the wife out and did the old fashion method of bleeding. Solid fluid at each caliper just like before but nothing at the pedal. So then the next step was to unbolt the rear calipers and hold them vertically and do it all over again. Sure as )*&)! air was released and the pedal finally had some pressure. Within 10 minutes it was hard as a rock.

It amazes me sometimes how my brain works. Thought that solid brake fluid at the bleeders was the defining mark. Finally my stubborn ways gave way to listening to a PROFESSIONAL and guess what? He was right.


Dave

[Dave_Darling]

Wait, what??? The calipers were not in the regular orientation, with the bleeder valve on top? You had them laying down or something? (Sorry, I can't really picture what you're talking about!)

We've had people trying to bleed brakes from a bleeder on the bottom of the caliper (some had two bleeders; sometimes people swapped left and right calipers) and you will never EVER get a good pedal that way.

--DD

[Downerman]

I have a great pedal right now. Eric didn't think that was an issue either. My machine shop guy has a race car and his calipers are laying flat as well. Just talked to him and he was like "of course you have to stand them up to bleed them".

It's not an issue.


Dave

[rgalla9146]

......... you would have had your solution much sooner if you mentioned your calipers were at the south pole.
oh..... and now the car has "brakes" not "breaks"

[Downerman]

You are correct sir!!! As I said above, my logic of using the suction brake bleeder and having no air was flawed. Didn't even dawn on me to mention the calipers laying horizontal. Live and learn I guess. Thanks everyone, appreciate everyone's comments.

Dave

[ClayPerrine]

I had the same issue on my old Jeep truck. I had to replace the front calipers, and FLAPS could only get two left calipers. Considering I needed to get the truck back on the road, I bought the two lefts. So to bleed the right caliper, I have to take it off, put a block of wood in between the pads, and flip it over. It works fine, but it is a pain in the ass to bleed.

Glad you found it. Now go (IMG:style_emoticons/default/driving.gif)