Bad brake master cylinder?

[Riddlemr2]

Well, the accumulator has been replaced by the PO, my mechanic (Foreign Toys in Fort Lauderdale) tried swapping the pressure switch, but the problem won't go away.

The brake pedal has a strange "push back" feel, which may or may not be normal, but the biggest concern is the half second delay between when I hit the brake and when I actually begin to stop. He ran a test and found that the system is only making 1800psi of pressure, and I believe it should be over 3000psi.

Before I pay $2700 for a replacement system, is there anything esle for me to check? The PO's mechanic may not have known how to properly bleed the brakes when he replaced the accumulator, but that seems too inexpensive to be the real fix

[Paul93Lotus]

Well, the accumulator has been replaced by the PO, my mechanic (Foreign Toys in Fort Lauderdale) tried swapping the pressure switch, but the problem won't go away.

The brake pedal has a strange "push back" feel, which may or may not be normal, but the biggest concern is the half second delay between when I hit the brake and when I actually begin to stop. He ran a test and found that the system is only making 1800psi of pressure, and I believe it should be over 3000psi.

Before I pay $2700 for a replacement system, is there anything esle for me to check? The PO's mechanic may not have known how to properly bleed the brakes when he replaced the accumulator, but that seems too inexpensive to be the real fix

There is a specific system to bleeding as documented in the JG brake system. So that would be the first step. If he bled it like any other system it is not bled properly. There is also the possibility that the pump for the system in itself is bad and not bringing up the system to the correct pressure. Or maybe the relay is not working properly which could shut off the pump prematurely.

BLEEDING

Pretty much the last thing you should do after working on the ABS system. This is one of the most difficult brake systems to bleed. You can do it with one person using tubing, but its far easier with a helper. If you don't have help, then you will have to open the bleeder, attach clear tubing to the bleeder (the other end should be submerged in a jar with some brake fluid) and run into the car to perform the required task. Then go back, close the bleeder first, and remove the tubing. When checking the fluid level, its not entirely necessary to completely depressurize the system. Check to make sure a significant amount of fluid remains in the reservoir before continuing. However, if you add fluid, do not add it to the full mark unless you depressurize the system.

If you have already worked on the ABS system, and not turned on the key, then fill it to the FULL mark with brake fluid and replace the cover. Otherwise, depressurize the system by firmly stepping on the pedal 40 times. You will feel a difference when the charge is gone. Then fill it to the FULL marks and replace the cover. Have you're assistant turn on the ignition and allow the system to pressurize (about 40 seconds). If it takes longer than 60 seconds you may have a leak or other problem, turn off the ignition and double check everything.

Start at the RIGHT REAR caliper. Using a 10mm 6pt box end wrench (or a line wrench), make sure the bleeder will come loose. With the ignition on, have the assistant apply light pressure to the brake pedal until fluid comes out. Let it bleed for about 10 seconds, making sure no air comes out. Close the bleeder while fluid is still coming out, then release the pedal. Repeat if necessary.

Check fluid level.

Repeat steps 2-3 on the LEFT REAR caliper.

Move to the RIGHT FRONT of the car. The front brakes bleed in a conventional manner. Have the assistant press hard and hold on the pedal while you slowly open the bleeder. The pedal should drop towards the floor. Repeat several times until just fluid comes out.

Check Fluid Level.

Repeat step 5-6 on the LEFT FRONT.

Now you have to bleed the booster portion of the ABS Master Cylinder. There are two bleeder valves, one on either side of the MC, that can be loosened with an 8mm Box end wrench. Have your assistant press lightly on the brake pedal while you open the bleeder allowing fluid to come out, for about 10 seconds. Close the bleeder while fluid is still coming out, then release the pedal. Repeat if any air comes out. Repeat for the other bleeder screw.

Check the fluid level.

Check the brake operation. Make sure that the brake light switch is adjusted properly .

If you decide to replace, I would call this place first:

(www.priorreman.com) 1-800-444-4821 About $500 with a 3 year warranty. For more info on this brake system look here: www.tpsgarage.com, and go to brakes or powermaster III

Edited February 1, 2007 by Paul93Lotus

[Riddlemr2]

Well, my mechanic did more digging and found that the PO's mechanic put the wrong brake fluid in it...some sort of Jaguar mineral fluid instead of DOT 4.

I also called Prior remanufacturing. They haven't ever done a Lotus system, but said that if all the internal seals are the same as the Pontiac unit, they'll be able to rebuild it. The rebuild price has gone up to $780.

For the $800 repaired or $2700 new to replace what will still be a poor system, couldn't the entire thing be swapped for an aftermarket ABS unit? Does Brembo or Willwood make entire brake systems?

[fflyingdog]

Hi

Just a couple thoughts ,

1. Have you an Abs warning light? either flashing or steady?

2. Have you replaced the pressure switch? these can cause no end of problems and are in alot of cases the cause of many Abs malfunctions. The switch commands the pump to run to bring the system up to correct working pressure ,its very unlikely to be the accumulator. (for your info new pressure switch has a grey moulding and the old switch is black)

Cheers

Nick S4s

Edited February 1, 2007 by fflyingdog

[Paul93Lotus]

Prior hasn't done a Lotus system because the system is a GM Delco Powermaster 3 from a Turbo Pontiac Grand Prix! Most parts on the esprit save the short block, interior and body are not original Lotus parts...they are sourced from other manufacturers!

Just like the front non-brembo brakes....go to the store an most won't have a clue....tell them 84-85 Toyota Celica and voila, they now have them.

With the Esprit, you need to know what part was used from other cars, and need to look at the cross reference lists here on the boards.

[Artie]

Prior hasn't done a Lotus system because the system is a GM Delco Powermaster 3 from a Turbo Pontiac Grand Prix! Most parts on the esprit save the short block, interior and body are not original Lotus parts...they are sourced from other manufacturers!

Just like the front non-brembo brakes....go to the store an most won't have a clue....tell them 84-85 Toyota Celica and voila, they now have them.

With the Esprit, you need to know what part was used from other cars, and need to look at the cross reference lists here on the boards.

Yeah, sure is nice to buy a replacement TPS for $22!

Artie

[Riddlemr2]

I posted a new topic with the resolution to the brake issue...I finally understand the difference between a PO and DPO.