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HomeTech Articles > Bleeding 914 Brakes

Pelican Technical Article:

Bleeding 914 Brakes

Difficulty Level 2

Difficulty scale:
Adding air to your tires is level one
Rebuilding a 911 Motor is level ten

[Click on Photo]      After talking to many owners, it would seem that there are more methods for bleeding brakes on a 914 than there are cures for the common cold.  Fortunately, I have polled many people and tried several different solutions, and I think that I have come up with the best compromise solution.

     There are currently three methods of bleeding the brake system:

  • Pressure Bleeding.  This is where you have a reservoir of brake fluid, and place a positive air pressure force on the opposite side of the fluid, forcing it into the brake system.
  • Vacuum Bleeding.  This is where you fill the reservoir, and then apply a vacuum at the bleeder nipple to pull fluid through the system.
  • Family Member Bleeding.  This is where you recruit the one family member or friend who owes you a favor and have them stomp on the pedal repeatedly until the entire system is bled.  Note that this has nothing to do with the time that little Jimmy fell on the concrete and had to be rushed to the hospital.
Figure 1:
914 Proportioning Valve
     The method that I've come up with combines the first and the third methods described above.  Basically, I advocate bleeding the system with the pressure bleeder, and then using a family member to stomp on the pedal to free up the proportioning valve.  If the family member really owes you big time, you will be the one stomping on the pedal, and they can spill brake fluid all over themselves.  It is this valve, shown in Figure 1, that gives the vacuum and pressure bleeders so much trouble.  The valve requires a certain amount of pressure in order to get it's internal piston to activate.   Without activating this piston, the proportioning valve can trap air and create a spongy pedal.
Figure 2:
Eezi-Bleed Pressure System

Figure 3:
914 Brake Fluid Reservoir

Figure 4:
Bleed Nipple

    The first step in bleeding the 914 brakes is to fill the system with brake fluid.  Some people have suggested that colored brake fluid be used in order to determine when fresh fluid has been flushed through the entire system.  I used a pressure bleeder like the Eezi-Bleed System shown in Figure 2.  The system works by pressurizing a bottle filled with brake fluid from air in the spare tire.  Inflate your tire to 20 psi, fill the bottle, attach it to the top of the reservoir (Figure 3), and then connect it to the spare tire.   This will pressurize the system.  Note: brake fluid is highly corrosive and will mar paint very easily.  Bleeding your brakes is a messy job; keep yourself away from the paint and don't bleed the system in tight garage.  The probability of spilling on yourself and then leaning against your car is too great.

     Now start bleeding the system.   Start with the right rear caliper, the one that's located furthest away from the master cylinder.  You will have to remove the rear wheels of the car to easily get to the rear caliper.  The front wheels can be turned for access to the calipers.   Bleed the right rear caliper by attaching a hose to the bleed nipple, placing it in a jar, and then opening the valve with a 7mm wrench.  A bleeder nipple is shown in Figure 4, and can be opened by turning it counter clockwise.  Let the fluid out until there are no more bubbles.  If you don't have a pressure bleeder system, you need to find someone to press on the pedal repeatedly to force fluid through the system.  Another solution is to get a check valve and place it on the nipple while you stomp on the pedal.  This will work for getting fluid into the system but you will still need a second person to make sure you have bleed the proportioning valve properly.  If your rear caliper has two bleed nipples (some have one, others have two), bleed the lower one first.

     When no more air bubbles come out, then move to the next caliper.   Bleed them in this order:

  • Right Rear Caliper
  • Left Rear Caliper
  • Right Front Caliper
  • Left Front Caliper

Repeat until you can no longer see any air bubbles coming out of any of the calipers.  Make sure that you don't run out of brake fluid in your reservoir, or you will have to start over again.  It is wise to start with about a gallon of brake fluid.  Depending upon your car, and the mistakes you may make, it's wise to have an ample supply.

     Now, make sure that all the bleeder valves are closed tightly.  Disconnect the pressure system from the reservoir.  Now, get your family member to press down repeatedly on the brake pedal at least five times, and then hold it down.  Then open the bleeder valve on the right rear caliper.  The system should lose pressure, and the pedal should sink to the floor.  When the fluid stops coming out of the bleeder valve, close the valve, and then tell your family member to let their foot off of the pedal.  Do not let them take their foot off until you have completely closed the valve.  Repeat this motion for each valve at least three times.  Repeat this entire procedure for all the valves in the same order as described previously.

     Then, let the car sit for about 10 minutes.  Repeat the bleeding process at each corner.  The pedal should now feel pretty stiff.

     If the pedal still feels spongy, make sure that you have the proper clearances on your rear calipers.  For more information on adjusting the rear calipers, please see the Pelican Technical Article, Replacing and Adjusting 914 Brake Pads.   Also, you may need a new master cylinder, have a leaky caliper, or have old spongy flexible brake lines.

     If the pedal still feels spongy, Jim Pasha has another method that I will describe here.  He recommends having your family member step down on the pedal repeatedly and then hold it down, while you crack open the inlet line from the master cylinder.  The inlet line is the one that comes out from the firewall of the car.  Wait until fluid stops, tighten the connection, and then have your family member let their foot off of the pedal.  Then, repeat the procedure for the outlet line on the proportioning valve.  He suggests that this will alleviate air pockets in the internals of the valve.  Be sure to wear eye protection and wrap the proportioning valve with a rag so that brake fluid doesn't squirt everywhere.  Be sure to rinse off brake fluid that has spilled on painted surfaces with water.   Wiping it will only smear the paint more (I talk from experience here).

     Well that's about all it takes.  If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs.  Your continued support directly affects the expansion and existence of this site and technical articles like this one.  As always, if you have any questions or comments about this helpful article, please drop us a line.

Comments and Suggestions:
Ash Comments: I recently bought my first 914 that was supposedly "restored" but finding out the hardway that these details were overlooked. Great tips and thanks for putting this together so I can finally enjoy the car! If I have another pressure bleeder unit, what PSI do I run that? 20psi seems high, but wanted to confirm before I blow brake fluid everywhere
May 18, 2016
  Followup from the Pelican Staff: stay at 6 - 10 psi. - Nick at Pelican Parts  
DaveandLiz Comments: Here's an old racer's "I AM my pit crew" trick I learned years ago that has recently worked for me on our 'teener:

Get a small pop bottle with a screw cap should be clear and 6-8 feet of appropriate tubing to fit on the bleed nipple. Drill a hole in the plastic cap to fit the tubing snugly and insert the hose to the base of the bottle or just above. Crack the cap just so that no pressure builds up in the bottle. Crack the bleeder and then snug it by hand. Fit the other end of the long bleeder hose to the nipple and open about 1/4 turn. Return to the car and perform the bleeding - about 12 pumps or so once the bleeder line is primed with fluid the first performance will take more pumping to expel the air, so verify the reservoir level at 12-15 pumps. Snug the bleeder by hand or loosely with a wrench. Repeat as required, taking care to allow as little air to enter the tube as possible after removal.

Why this method? First, once the air is expelled and travels ahead of clean fluid, it can't return easily it helps if you arc the bleed tubing upward from the calliper. Second, you can place the bottle within eyesight no matter what corner you are bleeding. The bubble existing in the bleeder line when you fit the hose will 'blurp' into the bottle, then you will see clear fluid. Later still you may or may not see the air that was trapped in the car's line 'blurp' as well. Keep bleeding as long as you like until you are satisfied that no further air is trapped in that line.

The only danger in this procedure is that you as the sole wrench are handling the brake fluid AND climbing in and out of the car. Beware the paint... and good luck.

August 9, 2013
  Followup from the Pelican Staff: Thanks for the tip - Kerry at Pelican Parts  
jrenfrew Comments: Be careful with speed bleeders, they aren’t perfect either. I've seen it before where air is sucked back in around the threads of the bleeder back into the caliper. If you have "older" calipers and they have been serviced a lot, you stand a good chance of air leaking past the threads. The same issue can also mislead you if you are vacuum bleeding. Air can be sucked past the threads and out the bleeder making you think there is still air in the system. Went through a gallon of fluid before I found that!

It wasn’t mentioned in this article, using cheap isopropyl alcohol to flush an old dirty system first can help to get your system cleaner without having to waste the more expensive brake fluid, especially if you are using something like dot 5 fluids. Dot 5, although pricy, is silicon based so it won’t wreck your paint. I prefer to use it on my collector cars in case of brake system leaks or accidental spills.

Great article, got me all ready for bleeding my 914 for the first time.
July 11, 2011
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
Amphicar770 Comments: Nice article.

Pressure bleeders from companies like Motiv make bleeding a breeze. The other big winner is to replace your bleedvalves with Speed Bleeders. I have these on all my cars and they truly make brake bleeding a one person operation. These can be found in just about any auto parts store.
June 7, 2010
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
svsv Comments: another helpfull selection thanx
October 4, 2009
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts

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