tried everything and still soft brakes
- Thread starter stumpguy
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I had a bad brake booster on my old LeSabre that did an awfully good impression of a failed master cylinder.
Disconnect the vacuum hose to the booster, pump the pedal a few times to get rid of stored vacuum, and check if the brake pedal stays up when putting a good amount of effort into pressing the brakes down. Try pumping the brakes, and see if the pedal returns to its normal position. Then re-connect the vacuum hose and see if the symptoms return when the engine is started. If it does that, it's likely the booster has failed.
Disconnect the vacuum hose to the booster, pump the pedal a few times to get rid of stored vacuum, and check if the brake pedal stays up when putting a good amount of effort into pressing the brakes down. Try pumping the brakes, and see if the pedal returns to its normal position. Then re-connect the vacuum hose and see if the symptoms return when the engine is started. If it does that, it's likely the booster has failed.
Originally Posted By: stumpguy
have a 2002 silverado and my brakes are too soft.pads are 70-100%,no leaks,new master cylinder and bled them at least 5 times.It still feels like there is air in the lines,cant be the booster??
SAME thing on my '03 GMC Sierra, except just a soft pedal.
have a 2002 silverado and my brakes are too soft.pads are 70-100%,no leaks,new master cylinder and bled them at least 5 times.It still feels like there is air in the lines,cant be the booster??
SAME thing on my '03 GMC Sierra, except just a soft pedal.
I wonder if the rear calipers are seizing up? It is a known issue with them.
Probably need to cycle the ABS module. There was a similar thread on garage journal recently, and a proper ABS bleed solved it. Time for y'all to invest in the Autoenginuity enhanced GM software.
JHZR2
Staff member
My 98 s-10 also seems to me to have a soft pedal.
How long after the new master cylinder did the soft pedal begin ?
If it wasn't bled properly you'll never be able to get a firm pedal. And the same for the brake lines - if the brakes are not bled properly at the wheels you'll never be able to get a firm pedal.
I've always been amazed at how many mechanics, pros and amateurs, who do not know how to bleed brakes correctly.
Keith
If it wasn't bled properly you'll never be able to get a firm pedal. And the same for the brake lines - if the brakes are not bled properly at the wheels you'll never be able to get a firm pedal.
I've always been amazed at how many mechanics, pros and amateurs, who do not know how to bleed brakes correctly.
Keith
Master Cylinder Pushrod.
Too loose makes the pedal spongey, too tight makes brakes lock up.
Too loose makes the pedal spongey, too tight makes brakes lock up.
Find open dirt road, slam brakes to cycle ABS, rebleed.
I've done that to my 02 Chevy Silverado and 01 Toyota Tundra and it seems to firm up the brakes.
I've done that to my 02 Chevy Silverado and 01 Toyota Tundra and it seems to firm up the brakes.
Yep, those have a special bleed procedure to follow to remove all the air from the system. If you have a Tech II, Modis, etc scanner, you can go in and follow the instructions under the ABS module section.
Now if you don't have access to those tools and don't want to pay someone who does, next best thing is to slam on the brakes on a gravel road. It will cycle the ABS pump. Then bleed the brakes again. You may have to do this a few times to remove all the air.
Now if you don't have access to those tools and don't want to pay someone who does, next best thing is to slam on the brakes on a gravel road. It will cycle the ABS pump. Then bleed the brakes again. You may have to do this a few times to remove all the air.
Originally Posted By: wirelessF
Find open dirt road, slam brakes to cycle ABS, rebleed.
I've done that to my 02 Chevy Silverado and 01 Toyota Tundra and it seems to firm up the brakes.
Brake bedding by accident?
Seriously though, I made a jumper wire once to get the ABS to come on in my trucks. You need a factory service manual.
Find open dirt road, slam brakes to cycle ABS, rebleed.
I've done that to my 02 Chevy Silverado and 01 Toyota Tundra and it seems to firm up the brakes.
Brake bedding by accident?
Seriously though, I made a jumper wire once to get the ABS to come on in my trucks. You need a factory service manual.
Originally Posted By: KB2008X
I've always been amazed at how many mechanics, pros and amateurs, who do not know how to bleed brakes correctly.
Keith
That is TOO true.
If air gets in the ABS block, that's bad news until it's been cycled out, and the system re-bled. Heaven forbid the ABS is really needed before then.
I've always been amazed at how many mechanics, pros and amateurs, who do not know how to bleed brakes correctly.
Keith
That is TOO true.
If air gets in the ABS block, that's bad news until it's been cycled out, and the system re-bled. Heaven forbid the ABS is really needed before then.
sciphi has a good point n pumping the brake pedal , but don't take off any lines!
Just pump it when the car is off!
If the pedal is high and hard, you know which side is faulty.
Do you have rear drums? They can cause excessive pedal movement.
Factory adjusters always leave too much movement.
If you have rear drums, look there first.
Just pump it when the car is off!
If the pedal is high and hard, you know which side is faulty.
Do you have rear drums? They can cause excessive pedal movement.
Factory adjusters always leave too much movement.
If you have rear drums, look there first.
Originally Posted By: tpitcher
Originally Posted By: xxch4osxx
I wonder if the rear calipers are seizing up? It is a known issue with them.
Good one. I'll get some Syl-glide tomorrow and report back.
Reporting back.
Took off the WL Grease & put the Sil-Glide on the caliper pins & back of pads. It did seem to help!
Originally Posted By: xxch4osxx
I wonder if the rear calipers are seizing up? It is a known issue with them.
Good one. I'll get some Syl-glide tomorrow and report back.
Reporting back.
Took off the WL Grease & put the Sil-Glide on the caliper pins & back of pads. It did seem to help!
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