Brake Light & some fading.....help

[deandog311]

Newbie here but have been reading the forums for a while. I have a problem that I hope anybody, somebody can help me out with.

My brake warning light in the dash comes on after one or 2 brake applications and there is some fading. The first application of braking is solid just like ever but after that, there's times I think I'm going to rearend the guy in front of me or put the truck through the garage door. Brake fluid was a little low so I filled it, and have not yet looked at pads/rotors. I'm assuming that since the first application is solid that it's not the pads/rotors.

Can anybody steer my towards some troubleshooting techniques? Should I bleed them? Could it be an air-pressure problem? if so...what should I check?

My truck is a 1997 7.3L

Thanks in advance.
Deandog

[STurbo90]

Is the fluid level still okay after filling it up?

Are you talking about repetitive braking sequences?

[deandog311]

Yeah, the fluid level is fine after filling it....and it never really dropped after putting any new fluid in. And Yes, the problem comes after repeated brake applications....for example coming into my complex there's a series of about 4 speed bumps...works perfect on first one, slowly degrades as I go over next ones until I almost run through my garage door.

[STurbo90]

I would check how much vacumn pressure you have, should be at least 20" at idle.

[blageurt]

I think you have a master cylinder issue or a booster issue. Unplug the booster and see if the brakes still fade. If they do it's the master, It probably has an internal leak , which means it needs replacing.

[wdwrdj]

check the vaccum pump, thats what went on my 97. After the first pump the brakes pedal would go hard. Hope it works out for you.

[STurbo90]

after re-reading your reply, I don't think your problem is vacumn I was thinking of something else,

I think you have some kind of internal fluid leak somewhere. You probably want to check the master as suggested above, the wheel cylinders, and possible the rabs valve.

[deandog311]

I appreciate all the advice here....Is there a quick an easy method of checking the vacuum pump? How much did it cost to replace it? That's kind of what it is doing after the first or 2nd application, the pedal goes hard really have to push to get anything. Thanks in advance and I apologize for my lack of knowledge but trying not to have to take it in.

[blageurt]

Vucuum pumps are around 150 . . . It is the thing above the Power steering pump you just remove and replace after loosening / removing the belt. Make sure to use thread sealant and Torque it to proper spec.