Slow Brake Pedal Return/Brakes Lockup

[jpeek29208]

Hey all,

Tried searching but couldn't find what i needed.

My brakes have been giving me problems. The other day on the interstate my brakes randomly engaged while coming onto a on ramp while applying no brake pedal. I got the car off the road and the brakes were frozen and wouldn't release, so I had it towed home. The fronts seemed to be the culprit as they were the ones that were smoking and the burning smell was coming from.

Now that the car is home, the brakes have released, but I've noticed a very slow pedal return when I pump them at all, with the car on.

So far I've bleed the brakes and replaced both front calipers. The master was replaced about a 1.5 years ago.

Any Ideas?

Josh

 

[mecevans]

lines?

 

[jpeek29208]

it seems if the lines had a hole in them that the brake pedal would fall to the floor instead

 

[mecevans]

could be some crap stuck in them?

 

[87tomanymods]

have you checked the system for contamination . oil in the system can cause very odd and unpredictable problems (due to the rubber seals swelling)

 

[jpeek29208]

I completely flush the entire system out and it flows fine and the fluid looked good to.

I went and drove again, and sure enough same thing. Brakes locked up but this time I noticed all four brakes locked, as spit water on them and tons of steam came off

I never touched the brakes since I left my house and the engaged.

Any other ideas, this is a pretty simple system. Could it be the master?

Josh

 

[jpeek29208]

oh forgot to add, im non-abs

 

[87tomanymods]

If it was contaminated flushing would do no good it ruins every part exept the metal lines . Do your self a favor and check it any way all you need is a cup of water and a straw. Put some of the brake fluid in the watter and mix it up. If it seperates your screwed . ( best if done before flushing but id still check)

 

[Asterix]

You should check the operation of your vacuum booster. It has the power to engage the brakes without you touching the pedal, especially if it's misadjusted. One of the valves inside may have died. You can, though it's a good workout for your right leg, drive the car with the booster disconnected. Keep something in the car to plug up the vacuum line for when you disconnect the booster.

One obvious test is to drive the car until the brakes lock, then stop and pull off the booster vacuum line. If the brakes suddenly unlock, it's the booster.

One warning - don't buy a A1 Cardone rebuilt booster. They can't seem to make them to hold vacuum over more than an hour or so.

Asterix

 

[Moy]

When you flush contaminated fluid out you're technically supposed to change out the old flexible brake lines.

 

[RiyadYar]

the first thing i would check is the booster very easy test take off the vaccum line to it and see if the pedal is hard to press.. i had this same problem happen to me it ended up being the brake calipers were getting stuck

 

[87tomanymods]

When you flush contaminated fluid out you're technically supposed to change out the old flexible brake lines.

actualy if its contaminated you have to change the master cyl, prop valve, hoses, and calipers. (anything with rubber seals)

 

[Moy]

actualy if its contaminated you have to change the master cyl, prop valve, hoses, and calipers. (anything with rubber seals)

I know that. I should have put "also" in my previous post.

 

[jpeek29208]

well did some more testing with a local guy and it ended up being the brake booster thats dead. once we unplugged the booster the pedal return was normal and the brakes never locked up.

Now I have to find a new booster.

Thanks guys,
Josh