Trouble with brake bleeding, I can't get any pressure in the system Options

[Lozgib]

Hi. I'm new to Porsche 914 ownership so please go easy on me. I have owned vw splitscreen buses for 30 years and restored loads of them though.

I bought a California 914 a few months back that is running fine now but had been sitting for a number of years needing the brakes restoring as all four callipers had sized and master cylinder leaked.

I replaced all four callipers with rebuilt OG units from a reputable USA supplier together with a new master cylinder. I've bled the system 4 times using the easy self pressure method and combined traditional two person method and also combined both together as described on forums.

I get clear brake fluid at each wheel with no bubbles but I have no pressure at all at the pedal. It goes straight to the floor.
I've read every brake thread on this and other forums and can't find a solution. I have not replaced the pressure regulator as they aren't available her in the uk but would that cause zero pressure?

I'm thinking there may be an issue with one or more of the callipers. I've got no leaks I can detect on the system. I'm stumped and lost for what to try next?

Any help would be appreciated.

[GeorgeRud]

Bleeding the brakes can be a chore, and their have been issues with defective master cylinders as well.

I've had the best luck by pressure bleeding the system, then taking the car out for a ride along some bumpy roads, then pressure bleeding the system once again. I've been amazed how many more bubbles appeared after the ride, even though the fluid was running clear before.

Best of luck, you'll get it figured out then let folks know what you found.

[Perry Kiehl Clone]

Here's how I bleed a 914 brake system, from my post back in Mar 05.

Remember the "Search" function is your friend!

Get a spare cap for the brake fluid reservoir.
Get a tire valve & stem.
Drill a hole in the center of the reservoir cap, the same size as the hole in a wheel (or measure the narrow part of the tire valve).
Pull the valve stem through the hole.
Remove the plastic screen in the reservoir.
Fill the brake reservoir completely, not to the fill line, all the way full to the bottom of the tube that holds the plastic screen.
Put on your new modified pressure bleeder cap.
Drain your air tank to 10 psi, for cheaper compressors setting the regulator at 10 psi may not work. If you put too much pressure in the system, you'll blow off the blue lines that connect the supply lines to the reservoir, or worse.
Take a clip on air chuck and clip it on your new pressure bleeder cap.
Bleed the brakes, starting at the furthest bleeder from the master cyl, and finish at the bleeder nearest the master cyl.
Bleeding sequence (RR-LR-RF-LF) EDITED FROM ORIGINAL POST
Pump the pedal hard about ten times and repeat the procedure.
Do not get brake fluid on painted surfaces it will ruin them.
If the pressure bleeder cap retains pressure, bleed it down before taking it off the reservoir.
This works very well, and makes it a one person job.
Replace brake fluid every two years.
Properly discard used brake fluid.

[N_Jay]

You said "Easy pressure method".
Do you have a pressure bleeder?

When you do the pump the peddle method, do you feel pressure build up?

[porschetub]

Bleeding the brakes can be a chore, and their have been issues with defective master cylinders as well.

I've had the best luck by pressure bleeding the system, then taking the car out for a ride along some bumpy roads, then pressure bleeding the system once again. I've been amazed how many more bubbles appeared after the ride, even though the fluid was running clear before.

Best of luck, you'll get it figured out then let folks know what you found.

(IMG:style_emoticons/default/agree.gif) totally I didn't get at all stressed about ,drove the car maybe 50kms over my sh#t entry road one more bleed and perfection,power bleed to change fluid and used one man bleeder for getting the last of the air @ the calipers.....8 bleeders on my brakes keeps you working (IMG:style_emoticons/default/biggrin.gif)

Edit...hope its not a URO m/cylinder !!!

[87m491]

Not sure why anyone would go through this much trouble when you can get a $15 one person vacuum bleeder from Harbor freight! That said why spend $15 when you can try the method offered at the PMB site.

http://www.pmbperformance.com/gravity-bleed.html

It works well. I just went through this on my new to me 74. Installed new M/C as well as 4 soft lines and then bled all 4 calipers. Having bled many cars and motorcycles before, I too was a bit dismayed that the pedal really never came back going caliper to caliper. (even after bleeding both top and bottom bleed screws) I went through a quart of fluid chasing out crap, be sure to keep the reservoir filled as the fluid can really get running! A few extra pumps after buttoning up the last one and voila, firm pedal. As others have said a short road trip might dislodge the last bubbles. I used the soft mallet and tap method. Keep at it any you will get it!

Here's how I bleed a 914 brake system, from my post back in Mar 05.

Remember the "Search" function is your friend!

Get a spare cap for the brake fluid reservoir.
Get a tire valve & stem.
Drill a hole in the center of the reservoir cap, the same size as the hole in a wheel (or measure the narrow part of the tire valve).
Pull the valve stem through the hole.
Remove the plastic screen in the reservoir.
Fill the brake reservoir completely, not to the fill line, all the way full to the bottom of the tube that holds the plastic screen.
Put on your new modified pressure bleeder cap.
Drain your air tank to 10 psi, for cheaper compressors setting the regulator at 10 psi may not work. If you put too much pressure in the system, you'll blow off the blue lines that connect the supply lines to the reservoir, or worse.
Take a clip on air chuck and clip it on your new pressure bleeder cap.
Bleed the brakes, starting at the furthest bleeder from the master cyl, and finish at the bleeder nearest the master cyl.
Bleeding sequence (RR-LR-RF-LF) EDITED FROM ORIGINAL POST
Pump the pedal hard about ten times and repeat the procedure.
Do not get brake fluid on painted surfaces it will ruin them.
If the pressure bleeder cap retains pressure, bleed it down before taking it off the reservoir.
This works very well, and makes it a one person job.
Replace brake fluid every two years.
Properly discard used brake fluid.

[bigkensteele]

Are all of your bleed valves pointing up? Easy mistake to make when you have taken the calipers off. Just asking.

[mgp4591]

All good suggestions....
To start off, I'd clamp off all of the brakes at the hoses on each wheel using brake clamps (which actually are good to have for lots of reasons and can be purchased for not too much). This isolates the master cylinder from the calipers, then see if you've got pressure at the pedal. If not, you've got a bad m/c. If you've got pressure, start bleeding at the wheel furthest from the m/c, being the r.r., then the l.r, r.f., then l.f. That should eliminate each wheel in turn and you should be able to isolate which wheel is giving you issues.

[Mikey914]

Did you buy a URO master cylinder?

This is exactly the problem I experienced.

They have a tendency to fail internally.
Just curious.

[87m491]

"Bleed valves pointing up"?! Not sure I follow, all my bleed valves are horizontal and can only point one way when installed....

Are all of your bleed valves pointing up? Easy mistake to make when you have taken the calipers off. Just asking.

[N_Jay]

"Bleed valves pointing up"?! Not sure I follow, all my bleed valves are horizontal and can only point one way when installed....

Are all of your bleed valves pointing up? Easy mistake to make when you have taken the calipers off. Just asking.

They are on the upper side not lower side of the caliper, correct?
?

[jmitro]

Not sure why anyone would go through this much trouble when you can get a $15 one person vacuum bleeder from Harbor freight!

No doubt! Except I'd get a slightly higher quality bleeder

https://www.motiveproducts.com/collections/...oled-vw-bleeder

[Bartlett 914]

"Bleed valves pointing up"?! Not sure I follow, all my bleed valves are horizontal and can only point one way when installed....

Are all of your bleed valves pointing up? Easy mistake to make when you have taken the calipers off. Just asking.

They are on the upper side not lower side of the caliper, correct?
?

What he is getting at is I believe early cars the front calipers were different for right and left side. If these get reversed, the bleeders are low on the caliper. The bleeders must be high on the caliper.

[cary]

Was doing some parts research this AM.
PET shows left and right fronts on both early <72 and late.

Same with the rear. But rears have same part for all years.

[87m491]

My 74 has 2 bleeders on each caliper, there is always one on the top, but one on the bottom also!
(IMG:http://www.914world.com/bbs2/uploads_offsite/i723.photobucket.com-14731-1477250981.1.jpg)

"Bleed valves pointing up"?! Not sure I follow, all my bleed valves are horizontal and can only point one way when installed....

Are all of your bleed valves pointing up? Easy mistake to make when you have taken the calipers off. Just asking.

They are on the upper side not lower side of the caliper, correct?
?

[Lozgib]

Wow guys thanks for all the helpful comments and suggestions. Really appreciated.

I guess it's my fault not giving enough detail but to clarify. I've searched all threads I could find and followed all the advice I could find re bleeding. I'm using a self bleed system we call easy bleed in uk with 15psi pressure. I've done the advised pressure bleed together with the pump the pedal too as described. I've done it so many times I've used over 2litres of dot 4.

I like the idea of blocking off the four calipers and seeing if I can get any pedal. I will def try that to see if it's the MS that's failing rather than a calliper. So thanks for that advice. I can there after if ok work out which wheel is the issue one by one.

I can't recall which MS I bought but it was via Porsche dealer in USA but I'm beginning to suspect that the MC may be the issue. I did have issues getting the two inlet grommets to fit snug and although they don't leak I wonder if these are not seated correctly. If the MC is failing internally it may be the answer. Blocking all four callipers as suggested will hopefully give the answer next weekend.

The issue of the font callipers being the wrong way round as suggested will be explored too. From memory the bleed nipples are at the bottom of the calliper not the top. The rears have two nipples each.

So to Summarise I have no pedal at all. Never any pressure but have no bubbles in the system. Used the high pressure bleed and traditional friend bleed methods and also combined with pumping the pedal together with the pressure system. All a number of times and never any pedal resistance. After thinking and getting all your helpful comments it makes me think it's the new MC that must be the issue. I am reluctant to remove and refit as it was a pain to fit with the two inlets but if needs must then that's the way forward.

I'll update next weekend after hopefully finding the issue. Once again thanks for all the very helpful suggestions.
Loz

[Lozgib]

Having re read Bartlet's reply. My bleed nipples are def at the bottom of the callipers so does this mean I've fitted the two front callipers the wrong way round? And would this be the problem.
Thanks.

[Mikey914]

If you have no pressure at all, I would be very suspect of the master having an internal failure. Regardless of where you got it. The ATE will have casting marks on it if it's theirs. I would find my reciept if it's fairly current and clean you may be able to return. I really think this is your problem.

[Lozgib]

Mikey
Thanks. I think your right. The car is located away from my home so I can only work on it at weekends but the MC is only 2 months old and was new. Unless the fronts fitted the wrong way round would cause the same pedal issue!

[JPA914]

If your bleed nipples are at the bottom of your calipers, that is at least a major part of your problem...period.

Air bubbles rise in a liquid (brake fluid) so you'll never get them out if you don't have a high point in the system from which to purge them.