Brake pedal went a little soft...

I was driving back to my dorm today and I hit the brake pedal to stop at a light. When I did, the pedal went the normal distance with the right amount of resistance (that I am used to) but then it felt like some sort of barrier broke and it went quite a bit further suddenly.

I tested it repeatedly on the way back, and it did the same thing every time, except there wasnt a threshold where it used to stop. It sort of went spongy, but not entirely.

The brakes also seem to still stop fine, I just want to know what it could be and if I am going to randomly lose breaks at some point soon...


thanks

 

Check for moisture on the brake lines, you probably have a leak in the lines somewhere.

 

could be the wheel cylinders mine was doing the spongy pedal . i pulled the rear tires to replace the shoes and noticed the driver side was leakin fluid and the rubber boots on the ends were thin and looked like swollen olives

 

Hmm interesting... I also have changed in the past year the calipers, rotors, pads in the front and the shoes, drums, and hardware in the back.

 

Maybe your master cylinder is bad?
That was the case with my S-10 when I had a similar symptom.

 

mine does this too. usually when the engine rpm's change when the heater or ac is on while sitting at a light. when this happens the truck will crawl forward

 

Crawl underneath the truck and start looking for leaks/or oil residue near where the brakes/lines are.

Something else to try - have a buddy sit in the truck (preferably running, in park or neutral, ebrake on). Have your buddy step on the brakes as hard as he can..... while you crawl underneath and look for any signs of leakage.

A hairline crack won't be noticable until you put it under load.

 

OK I will do that when I go home this weekend. Can I drive around a little in the meantime or is that a bad idea?

 

bump...anyone know if im gonna die if i drive this damn thing too much?

 

Mine has done this since I got it(5 or 6 months) There's some seals leaking on mine in the back, I never noticed until I swapped my wheels out. I haven't even looked into fixing it. It's done fine for me.

What seals could this be and about how much would it cost to fix it? Sorry to hi-jack op, but I think you'll be fine.

 

The only place I would drive it would be to someone who can diagnose and fix the problem. The brakes might seem o.k. now, but what if you have to make a panic stop? You may feel like you're being extra careful, but what if some bonehead-talkin-on-a-cell-phone pulls out in front of you, you jam on the brakes and whatever was performing marginally gives up the ghost?

 

Exactly what gozar has said...

I wouldn't feel safe myself. If you knew exactly what the problem was - then you might be able to drive it for short (slow mph trips) depending on what the problem was. But, since you don't know what the problem is, I woudln't push my luck.

 

alright thanks. I'll drive it to my mechanic when I get a chance, I wish I could fix it myself, but I'm just to damn busy right now as a student.

 

OK, so heres an update:

I still have that brake pedal problem, but I figured out that if I press it all the way past where it went originally (theres kind of a weak threshold there, but then it travels another 50-60% further) and release all the way up, when I press it down immediately after it only goes to where it should go.

I don't know if that makes sense in writing, but thats what I have discovered and I want to see if it helps with the diagnosis

 

You can't make a diagnosis just from pedal travel....too many variables.

Did you check the condition of your brakes (shoes, pads, rotors, etc)?
Did you check for any leaks? Check your fluid level?

How's your ebrake engage? How many clicks does it go when you pull the handle?

 

I would put my money on the master cylinder being bad.

 

I replaced all brakes (rotors, pads, calipers 1 year ago, shoes, hardware, drums 8 months ago). I have checked the fluid level in the past week several times and it has not gone down at all.
Ill check for leaks again, but haven't found any yet.

My ebrake is already shot...pulls out like 25 clicks (norm is 12-18), one of the levers on the back is frozen, and it doesn't hold the truck. But that is nothing new...that's been the case since I bought the truck.

Master cylinder then?

 

When you replace the rear shoes - did you inspect the shoe wear? How were they wearing?

Did you inspect, clean, and/or replace the star wheel adjuster? How about all the rear springs, etc (there are rear drum rebuild kits available)

I would get the ebrake fixed first.....

Did you replace the rear cylinders?

Before jumping to conclusions on the master cylinder, I'd bleed the brakes entirely - this might flush out any particles in the fluid and/or if you find air in the system, then you know you have a hairline leak somewhere.

 

Yoy either have a leak, or a bad master cyl. When your pushing the pedal a couple of times your "pumping it up". Either way check for a leak now, when it finally lets go it isn't gonna be any fun, and most likely lead to a accident.

 

sounds like a master cylinder to me. if you have any tools and about an hour or so its pretty easy to fix. remember where the lines went and bleed your brakes afterward.