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gunny44, technician/shop foreman
Category: Car
Satisfied Customers: 360
Experience:  40 years experience, engine diagnose, transmissions, Ford, Pontiac, GM, Isuzu, 12 years with Kia
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99 isuzu trooper: Brake pedal went almost to repair

Customer Question

I have a '99 isuzu trooper. Brake pedal went almost to floor. I immediately went to closest auto repair. They replaced master brake cylinder. The brake pedal was still soft. They said bleed brakes and still soft. Went to a Nissan Dealership and they said they didn't have proper equipment to test brake pressure of isuzu and suggested Isuzu dealer. Help! Could yopu please tell me what to do ? Thanks. Awaiting your reply.
Submitted: 8 years ago.
Category: Car
Expert:  gunny44 replied 8 years ago.

Hi heneryj1999

Without feeling the brakes this may be hard to resolve. Please answer my questions as accurately as you can.

How did the brake pedal feel before it went to the floor?

Was the master cylinder empty when you took it to the first shop?

Does this vehicle have ABS? (anti lock brake system)

Now do a test for me. Start the engine and leave it in Park. Push the brake pedal down and hold it for a few seconds. (note where the pedal is) Now pump the pedal 2 or 3 times and hold it again and see if it is in a higher position. Keep pressure on the pedal and see if it fads and starts to go lower to the floor.

Do this a few times and let me know the results. I can't promise to pin-point this but I will try to get you in the right direction. Fixing cars in today's day and age is hard enough but doing it on the pc is a real challenge.

I will do my best. Gunny44





Customer: replied 8 years ago.

Hi Gunny44


Thanks for quick reply.


I just realized my car left in parking lot.


Will have to retrieve it and

will do the test suggested and advise.


Thanks for your patience.



Expert:  gunny44 replied 8 years ago.

Whenever. No rush on my end. I'll be on and off during the day. Lot's of yard work to do before the winter.


Customer: replied 8 years ago.

Hi Gunny44:


I was on way out of town when I got your reply and couldn't follow up as I also didn't have car at home.


Just got home and a.) I am answering your questions and providing results of the test you be performed.


1. How did brake feel before it went to floor. ? Soft ! But brakes never actually went

to floor, but felt like it was about to go to floor.


2.. Master Cylinder was not empty when I first took car to shop.


3. Vehicle has ABS (anti brake lock system ).


4. Brake Test:

a. Started engine in Park position.

Pushed brake pedal down and it went to about 2" above floor from

height of 6" above floor.

Pumped brake pedal 2-3 times and pedal came up to a higher position,

kept pressure on pedal and it settled to about 3" ABOVE FLOOR



B I repeated Brake test above a couple more times and got the same result.


Pardon the late response.


Look forward to your reply.






Expert:  gunny44 replied 8 years ago.

Hi Henryj999

From your description I'm not so sure the master cylinder was the problem because this problem basicly still exits. I would be more apt to look for frozen caliper pistons, frozen caliper slide pins, worn out rotors and brake pads. The brake proportioning valve could also be stuck causing only front or rear brake action. Bleeding the system with the engine running often frees this valve. (the hint here is that the other shop wanted to test brake pressure leading me to think that they couldn't get a decent squirt of fluid out of either the front or rear bleeders)(maybe this machine exists but I never saw one nor had use for it).

For your safety and your family I would strongly suggest that this Trooper's brake system be totally checked. I know my answer to your question is of general nature but without being there I can't be sure of your problem and I will not guess on a saftey issue.

I don't expect you to accept since I didn't answer you completely. If you wish get back to me and I will opt out and see if another expert would care to tackle this.

Regards. Gunny44 Good luck. Get back to me if you have any more questions on this.


Following I have the proper brake bleeding procedure for you in case you want to try bleeding again. It's worth a shot.



A bleeding operation is necessary to remove air from the hydraulic brake system whenever air is introduced into the hydraulic system. It may be necessary to bleed the hydraulic system at all four brakes if air has been introduced through a low fluid level or by disconnecting brake pipes at the master cylinder. If a brake pipe is disconnected at one wheel, only that wheel cylinder/caliper needs to be bled. If the pipes are disconnected at any fitting located between the master cylinder and brakes, then the brake system served by the disconnected pipe must be bled.

  1. For 4-Wheel Antilock Brake System (ABS) equipped vehicle, be sure to remove the ABS main fuse 40A located at the relay and fuse box before bleeding air. If you attempt to bleed air without removing the main fuse, air cannot be let out thoroughly, and this may cause damage to the hydraulic unit. After bleeding air, be sure to replace the ABS main fuse back to its original position.
  2. Set the parking brake completely, then start the engine. NOTE: The vacuum booster will be damaged if the bleeding operation is performed with the engine off.
  3. Remove the master cylinder reservoir cap.
  4. Fill the master cylinder reservoir with brake fluid. Keep the reservoir at least half full during the air bleeding operation
  5. Always use new brake fluid for replenishment.
  6. In replenishing brake fluid, take care that air bubbles do not enter the brake fluid. When the master cylinder is replaced or overhauled, first bleed the air from the master cylinder, then from each wheel cylinder and caliper following the procedures described below.
Bleeding The Master Cylinder
  1. Disconnect the rear wheel brake pipe (1) from the master cylinder. Check the fluid level and replenish as necessary. If replenished, leave the system for at least one minute.
  2. Depress the brake pedal slowly once and hold it depressed.
  3. Completely seal the delivery port of the master cylinder with your finger, where the pipe was disconnected then release the brake pedal slowly.
  4. Release your finger from the delivery port when the brake pedal returns completely.
  5. Repeat steps 7 through 9 until the brake fluid comes out of the delivery port during step 7. NOTE: Do not allow the fluid level in the reservoir to go below the half-way mark.
  6. Reconnect the brake pipe (1) to the master cylinder and tighten the pipe.
  7. Depress the brake pedal slowly once and hold it depressed.
  8. Loosen the rear wheel brake pipe (1) at the master cylinder.
  9. Retighten the brake pipe, then release the brake pedal slowly.
  10. Repeat steps 13 through 15 until no air comes out of the port when the brake pipe is loosened NOTE: Be very careful not to allow the brake fluid to come in contact with painted surfaces.

  1. Bleed the air from the front wheel brake pipe connection (2) by repeating steps 7 through 16.
Bleeding The Caliper
  1. Bleed the air from each wheel in the order listed below:
    • Right rear caliper
    • Left rear caliper
    • Right front caliper
    • Left front caliper Conduct air bleeding from the wheels in the above order. If no brake fluid comes out, it suggests that air is mixed in the master cylinder. In this case, bleed air from the master cylinder in accordance with steps 7 through 17, and then bleed air from the caliper.
  1. Place the proper size box end wrench over the bleeder screw.
  2. Cover the bleeder screw with a transparent tube, and submerge the free end of the transparent tube in a transparent container containing brake fluid.
  3. Pump the brake pedal slowly three (3) times (once/sec), then hold it depressed.
  4. Loosen the bleeder screw until fluid flows through the tube.
  5. Retighten the bleeder screw.
  6. Release the brake pedal slowly.
  7. Repeat steps 21 through 24 until the air is completely removed. It may be necessary to repeat the bleeding procedure 10 or more times for front wheels and 15 or more times for rear wheels.
  8. Go to the next wheel in the sequence after each wheel is bled. Be sure to monitor reservoir fluid level.
  9. Depress the brake pedal to check if you feel "sponginess" after the air has been removed from all wheel cylinders and calipers. If the pedal feels "spongy", the entire bleeding procedure must be repeated.
  10. After the bleeding operation is completed on the each individual wheel, check the level of the brake fluid in the reservoir and replenish up to the "MAX" level as necessary.
  11. Attach the reservoir cap. If the diaphragm inside the cap is deformed, reform it and install.
  12. Stop the engine.


Expert:  gunny44 replied 8 years ago.

Me again Henryj999

Just an after thought. You said the brake pedal was soft even before it went to the floor.

Has the master cylinder ever been very low and you added fluid? If this is the case then I would go for air in the lines and rebleed several times. That was the reason for my original questions to see if the pedal reacted as though air was trapped in them.

Still thinking. Gunny44


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Customer: replied 8 years ago.

Hi Gunny 44!


Thanks for your help.


This brake stuff has made me a bit nervous, so Isuzu referred me

to one of their last dealer facilities and I left Trooper with them.


You certainly responded in a professional manner.










Expert:  gunny44 replied 8 years ago.

Hi Henryj999

Thank you for the accept and compliment.

Only wish I could have said "Ah Ha" there's your problem!

You are doing the right thing and if you have any questions with this Isuzu dealer's diagnose get back to me and I'll try and explain it to you.

Regards XXXXX XXXXX it's not that big of a repair.