Brake warning Light!!!
Thread Starter
Pro
Joined: Oct 2006
Posts: 594
Likes: 3
From: Peoria IL
Brake warning Light!!!
Since I am on a roll with my other issues on the forum , Can you shed any light on my brake problem? I occasionally get the brake warning light come on and the pedal travels all the way to the floor , if I release the brake and re-apply the brakes firm up and are fine again . It does not happen all the time and seems to be more on gently braking rather than hard braking. I figured that it could be air in the brake lines so set about bleeding the brakes - followed the order in my manual and started with the rear drivers side - the bleeder screw sheered off 
Any way sorted that out and continued to bleed the system all the way around but when I took it for a drive this afternoon , the problem raised its ugly head again - any ideas on where to go next - do I go through the bleed procedure again or could there be some other cause? By the way , I do not appear to be loosing any fluid as the reservoir is still full and I checked for leaks around the wheels etc when I bled the first time.
As ever any advice would be very welcome
Any way sorted that out and continued to bleed the system all the way around but when I took it for a drive this afternoon , the problem raised its ugly head again - any ideas on where to go next - do I go through the bleed procedure again or could there be some other cause? By the way , I do not appear to be loosing any fluid as the reservoir is still full and I checked for leaks around the wheels etc when I bled the first time.As ever any advice would be very welcome
Race Director
Joined: Jul 2004
Posts: 12,680
Likes: 329
From: Scottsdale Arizona
I think that you have the right idea. I have no idea why, but some of these cars seem to be pretty hard to bleed properly. Just keep at it.
If this doesn't solve the problem, it could be the master cylinder. The fact that it happens on steady braking would be, to me, an indicator of this. The brake light, though, isn't. As I understand it, the brake light indicator comes on when there is a pressure difence in the front and rear systems. tis would lead me to believe that you just need to keep bleeding.
Good luck!
If this doesn't solve the problem, it could be the master cylinder. The fact that it happens on steady braking would be, to me, an indicator of this. The brake light, though, isn't. As I understand it, the brake light indicator comes on when there is a pressure difence in the front and rear systems. tis would lead me to believe that you just need to keep bleeding.
Good luck!
Burning Brakes
Joined: Nov 2004
Posts: 1,028
Likes: 0
From: San Antonio Texas
yup, been there, done that. sounds like air in brake lines. causes pressure differential in proportioning valve which causes brake light to come on. i had to bleed my brakes several times to get all the air out. keep bleeding them and you'll probably get it corrected. use a power bleeder if you've got one (or access to one). be sure your bleeding BOTH bleeders on the rear ones.
Le Mans Master
Joined: Nov 2001
Posts: 8,647
Likes: 1,871
From: LONG ISLAND
2025 C3 ('68-'73) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
Power Brakes ?
Originally Posted by britvette
Since I am on a roll with my other issues on the forum , Can you shed any light on my brake problem? I occasionally get the brake warning light come on and the pedal travels all the way to the floor , if I release the brake and re-apply the brakes firm up and are fine again . It does not happen all the time and seems to be more on gently braking rather than hard braking. I figured that it could be air in the brake lines so set about bleeding the brakes - followed the order in my manual and started with the rear drivers side - the bleeder screw sheered off Any way sorted that out and continued to bleed the system all the way around but when I took it for a drive this afternoon , the problem raised its ugly head again - any ideas on where to go next - do I go through the bleed procedure again or could there be some other cause? By the way , I do not appear to be loosing any fluid as the reservoir is still full and I checked for leaks around the wheels etc when I bled the first time.
As ever any advice would be very welcome
Any way sorted that out and continued to bleed the system all the way around but when I took it for a drive this afternoon , the problem raised its ugly head again - any ideas on where to go next - do I go through the bleed procedure again or could there be some other cause? By the way , I do not appear to be loosing any fluid as the reservoir is still full and I checked for leaks around the wheels etc when I bled the first time.As ever any advice would be very welcome
DO YOU HAVE ..............power brakes ??? maybe a vacume issue ?
just taking a stab at something not mentioned..........!!
ZIXXX PACKER
Le Mans Master
Joined: Aug 2006
Posts: 7,413
Likes: 1,552
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Brake warning light.
Hi britvette, your on the right track, if you say that none of the calipers show any signs of leakage and you have pressure bleed the system the next place to look is at runout. If one of your calipers is worped it will push the piston in and out as the wheel revolves, this will suck air into the piston, also a wheel bearing that is out of spec will cause the same problem, the front bearings are easy to inspect and or replace, the rear bearings are a problem as you need special tools to remove and replace them. Hope this helps, PG.
Burning Brakes
Joined: Jul 2006
Posts: 826
Likes: 22
From: Chicago Area
Originally Posted by greyghost79
yup, been there, done that. sounds like air in brake lines. causes pressure differential in proportioning valve which causes brake light to come on. i had to bleed my brakes several times to get all the air out. keep bleeding them and you'll probably get it corrected. use a power bleeder if you've got one (or access to one). be sure your bleeding BOTH bleeders on the rear ones.
Buy that power bleeder! It's worth every penny...and you can copletly flush all the old fluid out of the system. It's a pretty slick way to bleed brakes!
Good advice on the calipers/bearings Pete. I have heard of that before.
Instructor
Joined: Apr 2006
Posts: 212
Likes: 0
From: Woodland Park Colorado
Had a very similar problem with mine would bleed brakes and felt fine and in a few days brake light would come on. Also would have a slight squeek noise on the r/r. Found out that if your rotor run out is incorrect then it will pulsate air past the lip seal on the calipers and get air in system. Fixed the problem with a new set of rotor all the way around probably only need one rotor but I had planned on changing all 4 anyway. Also replaced all 4 calipers and shoes and brakes are great now and no brake light. Hope this helps
Best Regards
Best Regards
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Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
Originally Posted by woodlandcorvette
Had a very similar problem with mine would bleed brakes and felt fine and in a few days brake light would come on. Also would have a slight squeek noise on the r/r. Found out that if your rotor run out is incorrect then it will pulsate air past the lip seal on the calipers and get air in system. Fixed the problem with a new set of rotor all the way around probably only need one rotor but I had planned on changing all 4 anyway. Also replaced all 4 calipers and shoes and brakes are great now and no brake light. Hope this helps
Best Regards
Best Regards
Drifting
Joined: Jun 2005
Posts: 1,523
Likes: 1
From: grand prairie texas
I have had this exact problem with other cars in the past. I think the M/C is bypasing. For the $25 dollars cost from Oreilly auto parts it would be my first choice. Since you are going to have to open up the brake system anyway to easy out the snapped bleeder then bleed the system good and I would bet your brake problems are cured. Also depending how old your car is It might not hurt to replace those old rubber hoses going to the calipers.
Thread Starter
Pro
Joined: Oct 2006
Posts: 594
Likes: 3
From: Peoria IL
Thanks to all who responded - A quick question - if the problem is the master cylinder , is there any way to test if this is faulty.If the master cylinder is bypassing is there any way to prove this.
Thanks for any help you can give
Thanks for any help you can give
Race Director
Joined: Jul 2004
Posts: 12,680
Likes: 329
From: Scottsdale Arizona
Originally Posted by britvette
Thanks to all who responded - A quick question - if the problem is the master cylinder , is there any way to test if this is faulty.If the master cylinder is bypassing is there any way to prove this.
Thanks for any help you can give
Thanks for any help you can give
I'm less inclined to believe the runout idea given your symptoms. I would think that runout would show itself more over time. Your issue seems to happen pretty quickly. You can all but eliminate runout as an issue by switching to o-ring pistons in your calipers.
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
Originally Posted by britvette
Thanks to all who responded - A quick question - if the problem is the master cylinder , is there any way to test if this is faulty.If the master cylinder is bypassing is there any way to prove this.
Thanks for any help you can give
Thanks for any help you can give
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
The only test I see in the book goes like this...
Engine off pump the break at least 3 times then apply 80 lbs of pressure...pedal should not move more then 1.80 inches...
Check the one way valve with the hose going to the intake. Easy to remove...is it functioning one way only?
Jim
Engine off pump the break at least 3 times then apply 80 lbs of pressure...pedal should not move more then 1.80 inches...
Check the one way valve with the hose going to the intake. Easy to remove...is it functioning one way only?
Jim
Drifting
Joined: Jun 2005
Posts: 1,523
Likes: 1
From: grand prairie texas
Originally Posted by jdp6000
The only test I see in the book goes like this...
Engine off pump the break at least 3 times then apply 80 lbs of pressure...pedal should not move more then 1.80 inches...
Check the one way valve with the hose going to the intake. Easy to remove...is it functioning one way only?
Jim
Engine off pump the break at least 3 times then apply 80 lbs of pressure...pedal should not move more then 1.80 inches...
Check the one way valve with the hose going to the intake. Easy to remove...is it functioning one way only?
Jim
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
Originally Posted by jdp6000
The only test I see in the book goes like this...
Engine off pump the break at least 3 times then apply 80 lbs of pressure...pedal should not move more then 1.80 inches...
Check the one way valve with the hose going to the intake. Easy to remove...is it functioning one way only?
Jim
Engine off pump the break at least 3 times then apply 80 lbs of pressure...pedal should not move more then 1.80 inches...
Check the one way valve with the hose going to the intake. Easy to remove...is it functioning one way only?
Jim
Thread Starter
Pro
Joined: Oct 2006
Posts: 594
Likes: 3
From: Peoria IL
Tried the steady push on the pedal and it goes straight to the floor so put a re-man Master cylinder on this afternoon after bench bleeding - Problem solved (so far anyway!!) - brakes feel much firmer - the instructions for fitting the new MS say there is no need to bleed the brakes at the wheels but I think I am going to do it anyway , just to replace all of the old fluid and to make sure there is no air.
A BIG thanks to all who took the time to give their 2c worth
A BIG thanks to all who took the time to give their 2c worth
Burning Brakes
Joined: Jul 2006
Posts: 826
Likes: 22
From: Chicago Area
Originally Posted by britvette
Tried the steady push on the pedal and it goes straight to the floor so put a re-man Master cylinder on this afternoon after bench bleeding - Problem solved (so far anyway!!) - brakes feel much firmer - the instructions for fitting the new MS say there is no need to bleed the brakes at the wheels but I think I am going to do it anyway , just to replace all of the old fluid and to make sure there is no air.
A BIG thanks to all who took the time to give their 2c worth
A BIG thanks to all who took the time to give their 2c worth
