Question about 1998 GMC Jimmy

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No brakes I have a 98 Jimmy, I was driving and the brakes went out. I have replaced the brakes lines that were leaking, brake booster, master cylinder, all the abs stuff. When the jimmy is off the brakes pump up hard.. when you turn it on the pedal goes to the floor. I dont see any leaks and no air in the lines. Can't figure it out. Any advice?

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  • GMC Master
  • 5,742 Answers

I think the air is still there.

Posted on May 06, 2013

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Posted on Jan 02, 2017

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bayyagg
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SOURCE: I have replaced all brake

U forgot to bleed the BRAKE MASTER! When ur bleeding the brakes, make sure ur engine is RUNNiNG. I f u haven't got any BLEEDiNG tools that sucks all the fluid in ur car, try Bleeding first the master, 2nd will be the front wheel brakes, and the REAR brakes! If everything FAiLS go to ur nearest garage and have them fix it! Drive slowly, using ur engine and hand brake! Hope that helps u out!

Posted on Nov 17, 2010

  • 14036 Answers

SOURCE: 1997 gmc jimmy, have no

SOUND LIKE BRAKE BOOSTER BAD IF BRAKES WONT HOLD WHILE ENGINE RUNNING.BRAKE BOOSTER NOT HOLDING VACUUM,IT HAS A LEAKING DIAPHRAM. IF MASTERCYLINDER WAS BAD BRAKES WILL GO TO THE FLOOR WITH ENGINE ON OR OFF.AND YOU WOULD SEE WARNING BRAKE LIGHT FLASHING.

Posted on Jun 10, 2011

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1 Answer

Do you have to remove brake lines when you change the brake booster


Check rear of Master Cylinder--If wet likely Master Cylinder Leaking and Booster Damaged. They Should be replaced as a mated pair. (for warranty) and brake lines removed and system bled.

Oct 16, 2014 | 1988 Ford F 150

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How do i replace the brake booster on a 98 Mercury villager


12 specific steps will help you :
1 With the engine off, step on the brake pedal several times to relieve the brake booster of vacuum.
2 Press the brake pedal down and start the engine. Verify that the brake pedal sinks slightly. Turn off engine.
3 Remove the vacuum hose from the brake booster.
4 Remove the brake lines from the master cylinder. Remove the master cylinder from the brake booster. Plug the fittings to prevent brake fluid seepage.
5 Disconnect the brake pedal from the push rod.
6 Have an assistant hold the brake booster from inside the engine compartment. Remove the nuts that hold the brake booster to the firewall. These nuts are usually located under the dash on the interior of the firewall.
7 Remove the brake booster.
8 Install the new brake booster to the firewall. Tighten the mounting nuts.
9 Connect the push rod to the brake pedal.
10 Connect the vacuum hose to the vacuum brake booster.
11 Attach the master cylinder to the new brake booster and reconnect the brake lines.
.12 Bleed the brakes at the master cylinder.

Sep 24, 2013 | Cars & Trucks

2 Answers

Booster leaking fluid out the front of donut,where piston slides in and out.


Replace the master cylinder before the brake fluid ruins the booster.

Jul 31, 2011 | 1997 GMC Jimmy

1 Answer

1997 gmc jimmy, have no brakes, when truck is running pedal goes right to the floor. when the truck is off I can pump the brakes to build up pressure. there are no brake fluid leaks is it the booster or...


SOUND LIKE BRAKE BOOSTER BAD IF BRAKES WONT HOLD WHILE ENGINE RUNNING.BRAKE BOOSTER NOT HOLDING VACUUM,IT HAS A LEAKING DIAPHRAM. IF MASTERCYLINDER WAS BAD BRAKES WILL GO TO THE FLOOR WITH ENGINE ON OR OFF.AND YOU WOULD SEE WARNING BRAKE LIGHT FLASHING.

Jun 10, 2011 | 1997 GMC Jimmy

2 Answers

When i step on my brakes u hear a loud air noise and they are hard to stop


You need to replace the pads or u have a hose or line busted which immediatly needs to be replaced.Hope this helps and Thank You for asking.

Jul 19, 2010 | 1994 GMC Jimmy

2 Answers

98 wrangler - brake pedal goes all the way to the floor. The master cylinder and all brake lines are free of leaks. I'm not losing any brake fluid anywhere. I replaced the booster that is attached to the...


You changed the master cylinder and vacuum booster and have no leaks anywhere, but did you bleed the entire brake system after you did this work? A little bit of air in any of the lines will make the brakes ineffective.

May 30, 2017 | 1998 Jeep Wrangler

1 Answer

I replaced a brake line on my 1993 olds 98 and the brakes still don't work


Did you bleed the line for air? If the break line was by the master cilinder, got to bleed all 4 tires, otherwise, got to bleed the two front or two rear tires.

If you step on the brake and feels spongy, is probably air in the lines, if it feels hard check master cilinder, if you hear an air leak, check brake booster.

Mar 02, 2010 | 1993 Oldsmobile Ninety Eight

1 Answer

Experienceing loss of power to brakes


1. What is the Brake Fluid Level?
2. Are you losing any Brake fluid at all? Are there any puddles or noticeable wetness on the ground or on the tires/wheels? With vehicle parked, the reservoir filled (overfilled), and engine running: pump the brakes and check on the ground and back sides (inside portions) of the wheels. Look for any brake fluid leaks.
3. Leaks from Calipers usually means a leak from the caliper piston. The rubber seals will be wet.
Leaks from Drums usually means a leak from the wheel cylinder.
4. In any case of leaks from the wheels - replace the calliper OR wheel cylinder.
For caliper leaks: change the brake pads, and clean the rotors with brake cleaner.
For drum leaks: clean the drum and brake hardware with brake cleaner, and replace the shoes.
5. If no leak is detected from the wheel area's: check under the Master Cylinder for wetness indicating a possible leak.
6. If no leak can be found: you MAY have a rear seal leak in the Master Cylinder which is pumping Brake Fluid into the Brake Booster (that large disk looking thing attached to the fire wall, attached to the Master Cylinder in front).
a. Use a large drip/catch pan under the Van in the area on the Master Cylinder.
b. Disconnect the brake lines from the Master Cylinder using a flair wrench.
c. Remove the two nuts (12 or 13mm?) attaching the Master Cylinder to the Brake Booster. If you have been using a lot of fluid, and have found no leaks, here is a good possibilty that all that brake fluid has collected in the Booster; so when you detach the Master Cylinder from the Brake Booster, all that fluid will come rushing out!
7. If there is Brake Fluid inside the Brake Booster: there is no cleaning that out. Brake Fluid is very caustic to the seals inside the Booster and should be replaced.
8. Of course the Master Cylinder will also have to be replaced.
9. After replacing the Master Cylinder/Brake Booster - make sure you get all that spilled brake fluid off the engine compartment area parts! I use a brake cleaner, then mild soap and then water to rinse. Clean any Brake Fluid off Paint imediatley as it will quickly dissolves finishes and paint.
10. If no leak is detected and the Booster is clear, there may be problems with the Booster One-Way Valve. This is attached to the outside of the Booster and has a hose from an "advance" connected to it. This maybe malfunctioning where you are losing power. Replace this first before deciding to replace the whole booster (in cases of NON-LEAKS ONLY). If that did not work, there may be inner seals inside the Booster that have failed. That means a new Booster.
11. In any of the above cases: Make sure you bleed the Master Cylinder correctly and bleed the brakes (at each affected wheel) correctly. Any air in the brake lines will decrease your braking proficiency or could result in brake failure.

Let me know if this helped or if you have any additional information or questions. Feel free to contact me at FixYa.com!

Dec 10, 2009 | 1999 Dodge Caravan

2 Answers

I have a 1998 chevy s10 it has a good brake pedal with the engine off but with it running the pedal go'es to the floor and you can hear air at brake booster


Check for fluid leaks and your brakes. If you see no leaks and your brakes are in good shape replace the brake master cylinder and bleed the system. The air you hear is because the pedal went to the floor. If the booster goes bad the pedal will get so hard you can hardly push it at all. I think you will find if this happened suddenly either you have a major leak or the master cylinder went bad.

Sep 29, 2009 | 1998 Chevrolet S-10 Pickup

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