brakes work when they want

[Lown_ranger]

Havent posted much on here. been more of a lurker then anything else. I searched for anything like my situation and found nothing. Anyhow, heres my situation........ My brakes work for the most part. When they work the pedal is strong and they work great. Every once in awhile the pedal will go to the floor and it is almost impossible to stop. I have to be quik and pump the brakes and it will build pressure again. Im hopin its as simple as bleedin the brakes.

 

[Mark_88]

You could have air in the lines, but you'd feel that sponginess all the time...probably your booster is bypassing...do you hear a loud hissing noise when this happens?

 

[Lown_ranger]

No I dont hear any noise from there. I can never tell when its gonna do it, so Im not really listening for anything. But I will have to start now! Is there a simple solution to fixing the booster if it is bypassing or do I need to replace it all together?

 

[Earl43P]

Those symptoms are NOT booster-related. The booster can make the pedal stiff, but has no control over the pedal going to the floor.

Sounds like a bad Master Cylinder to me.

 

[Mark_88]

Yeah, if you don't hear a hiss it is not the booster...but when mine went the pedal went to the floor and it was very difficult to stop without serveral pumps...

Probably as Earl43p says...the master cylinder, but I would think that would be almost constant and getting worse (as in more frequent)...is it happening more often lately?

Not sure if it's actually related to your wheeling incident though...unless you sheer something off...and then you'd probably have no brakes when the fluid ran out...

 

[Lown_ranger]

No I wouldnt say its gettin worse. Its just kinda hit n miss. I cant even figure out when it happens most. I can almost gaurantee that it happens when I dirve to work and make my morning stop at the gas station to get my morning pop and pack of smokes. I can get there with no problems, turn the truck off and when I get back in and go to pull out the pedal goes to the floor. Ive noticed it also when Ive driven home and pulled into my neighborhood and go to stop or even just slow down to pull into my driveway.

 

[gotmudd]

Havent posted much on here. been more of a lurker then anything else. I searched for anything like my situation and found nothing. Anyhow, heres my situation........ My brakes work for the most part. When they work the pedal is strong and they work great. Every once in awhile the pedal will go to the floor and it is almost impossible to stop. I have to be quik and pump the brakes and it will build pressure again. Im hopin its as simple as bleedin the brakes.

You could have air in the lines, but you'd feel that sponginess all the time...probably your booster is bypassing...do you hear a loud hissing noise when this happens?

Those symptoms are NOT booster-related. The booster can make the pedal stiff, but has no control over the pedal going to the floor.

Sounds like a bad Master Cylinder to me.

Yeah, if you don't hear a hiss it is not the booster...but when mine went the pedal went to the floor and it was very difficult to stop without serveral pumps...

Probably as Earl43p says...the master cylinder, but I would think that would be almost constant and getting worse (as in more frequent)...is it happening more often lately?

Not sure if it's actually related to your wheeling incident though...unless you sheer something off...and then you'd probably have no brakes when the fluid ran out...

try bleeding your brakes, if that don't work there's a chance your master cylinder is gonna go south, i'm not sure how to test but you might want to check your proportioning valve, it might be intermittantly hanging up. i had the same thing happen on my truck[ the one in my sig] and it turned out all i needed was to bleed the brakes. FWIW, mine is manual brakes, no booster, which is why i didn't even steer you that way. if it was your booster gone bad it would act like you have manual brakes but much stiffer. i didn't have anyone to help me so i just took a partially full brakefluid container and attached a rubber line with a snug fit over the bleeder nipple and stuck that into the brake fluid and cracked the bleeder open making sure to keep the master cylinder resevoir full and pumped the heck out of it, and repeating for each wheel cylinder. almost as good as the pressure bleed you get at a shop, but better than the job you get from doing a two man because as long as you rubber line stays submerged and doesn't come off the bleeder nipple there is no chance to get air in the lines.

 

[Mark_88]

I used a one-man bleed kit...just a little plastic bottle and a clear hose...hange the bottle up above the cylinder...attach the hose to the bleeder screw...crack the bleeder and pump (a couple of times only) ...did all four in about an hour...

Bleeding the master itself is a bit trickier...not sure if it says to NOT bench bleed or if that was the clutch cylinder...but I had to have someone pump the brakes to do that...and it sat for four years with no fluid...

 

[Lown_ranger]

Thanks for the input! I will try bleeding them. I know thats the easiest process of elimination to figure out whats wrong. Thanks again!! And Ill post my findings.

 

[Earl43P]

Waste of time.

I'd replace the Master first. It is truly the only part that fits your symptoms.

Be sure they give you (or buy) a bench bleeder kit. You can do it without, but it's messy.

http://www.stoptech.com/tech_info/wp_howto_bleedbrakes.shtml

 

[Lown_ranger]

Ok so I think its fixed. Im not 100% sure yet. I forgot to mention that the brake light was on. I got home yesterday and pulled the parking brake release and kinda pulled the pedal up a little, turned the truck on and the light is now out. Drove to work this morning and had no problems with it. It actually felt like it had really good pressure. Let me know if Im just crazy or if the parking brake being slightly pushed in would have anything to do with it.

 

[Mark_88]

the pedal being down will engage the light switch...but that should not cause your brakes to fade like that...I'd say you're probably going to have another incident with them fading so be careful...but let us know what the fix was if possible...

Edit: the parking brake will cause a Brake light to come on in the dash...and if your MC shares the same light low fluid or possibly worn shoes or pads can also cause the light to come on...some vehicles have separate lights for brake fluid and parking brake...I know my Zuki does...but the 88 I have only has one light for both...

 

[Lown_ranger]

I didnt think it could be as easy as that! Thanks for the reply!