ok so i did the carquest blue semi metalic pad changout this weekend and threw on new rotors as well, brakes are spongy!!!! now my wife called me at work and said she almost ran a stop sign because the truck wouldnt stop. should i bleed brakes or what? This truck has had soft pedal since the day i bought it! thx in advance
Bill

 

hmmm... so your brake pedal lives in a pineapple under the sea????

It sounds like you need to bleed the brakes. Being a 97, you might want to flush them too if they really feel soft. Brake fluid is hygroscopic (absorbs water) and water is much more compressible so it can lead to softer brakes over time.

Other than that, check the flex lines to make sure everything looks ok. And look for any drips from loose fittings (or loose bleeder valves)

 

will check it out for sure, gonna have my dad help me bleed the brakes, guess i should just flush the system out completly while im at it. when i replaced the front pads on saturday i noticed i was leaking brake fluid out of the cap on my master cylinder when squeezing the pistons back in so i could re-install on the truck, and when i was done seemed like the fluid level was a little high even after loosing some fluid?

 

Water is not at all easy to compress. Besides the fact it can corrode things, the reason you don't want water in your brake fluid is that it will lower the boiling temp of your brake fluid. Old, dirty and water contaminated brake fluid is much easier to boil than good clean brake fluid (especially high quality fluid). Just like air, steam from boiling brake fluid or water is VERY compressible.

Sounds like the origininal poster has air or vapor somewhere in the sytem. As your wife found out, this can be dangerous.

Anytime you are down there doing pads you should at least bleed the brakes at the wheel cylinder and test the brakes before you give the wife the keys! BTW, you may have air or vapor in other parts of the system besides at the wheel's cylinders.

 

oh come on you dont think i would do a brake job and just hand over the keys do ya? i test drove the truck after competing the work, heck i even drove the truck over 100 miles before she drove it, was ok when i parked last night, but like i said they have always been spongy, she claimed it had no brakes at all? no shes got my moms mini van and i have to go work on the stupid truck tonight after work.

 

Is she a brake dragger? This can greatly increase the heat in the brakes and make it much more likely to boil, and would explain why they work for you and not for her.

If you are going to go through the trouble of replacing the fluid, spend a little more and get a high quality fluid that has a higher wet and dry boiling temp.

I've had excellent success with Motul 600 in my motorcycles, and in some cases it has noticeably improved fade and fluid boiling when compared to old dirty, lesser fluids. It is compatible with what is in our trucks. Specs are below.

Motul RBF 600 Racing DOT 4 Brake Fluid
Motul RBF 600 far exceeds DOT 3 and DOT 4 specifications. Bottles are filled with nitrogen to extend shelf life and eliminate contamination while factory sealed. Extremely high wet and dry boiling points help prevent vapor lock and fade. Many "problem" braking systems have been cured just by switching to Motul 600.

Motul RBF 600 Specifications:
DOT Rating - 4
Dry Boiling Point - 594°F
Wet Boiling Point - 421°F
Compatible with other fluids - Yes
Container - 16.9 fluid ounce (500ml) plastic bottles, factory filled with nitrogen to preserve freshness

 

thanks DBD, will check er out, get some dot 4 and a turkey baster to suck out the old stuff and just go to town on it! will post my results tomorrow.

 

If you are trying to bleed the lines and change the fluid by yourself, pulling fluid from the master cylinder reservoir with a baster is not going to do much.

Your results will be greatly improved by using vacuum bleeder like one of these http://www.amazon.com/s/104-9063089-...link%5Fcode=qs


They might have one in stock at your auto parts store.

 

just using the baster to pull the residual out of the master cylinder then add new fluid before i start bleeding em.

 

got the brakes bled last night and see a little improvment but still not happy with it. trucks got 182000 on it, do ya think its time for a new master cylinder? when the truck is off the brake pedal is firm, but as soon as you start the truck it goes spongy and to the floor. checked all my vacuum lines and cannot find a problem there as well and all brake lines, no leaks. help dont want to replace master cylinder unless i really have to thx.
Bill

 

This would indicate that your check valve is leaking... when the engine is off there is no vacuum stored in the booster and therefore the brake pedal feels hard as a rock. (for reference: a good check valve should provide about 5 pumps of the brake pedal before the vacuum is gone)

An easy check of the master cylinder... while sitting still with the engine running, press the brake pedal to achieve a normal stopping force. Hold it at that same force for about 60 seconds. If the pedal continues to drop away (once you achieve the force) it would indicate that you have a seal bypassing... or a leak somewhere in the brake system.

If the brake pedal holds steady under the force, it would show that the MC is probably fine and it is a bleed issue, or you need new flex lines.

 

thx for that info, when the truck is running an you hold the brake, it continually drops. where is this check valve at?
sounds like i may need to just go ahead and change the master cylinder

 

Check valve - not 100% sure for your model year, but usually they are located where the vacuum line hooks onto the booster... part of the "elbow" is a check valve.

Is your reservoir volume holding steady? The falling away pedal could also be a sign of a leak somewhere. I would carefully check all the wheels (for leaks at the calipers / drums?) before replacing the MC.

 

ok i know the check valve you speak of, no leaks have checked everything out a few times now, and yes the resevoir is holding steady level of brake fluid.

 

it would not be an external leak...

The point of that check valve is to maintain vacuum in the booster when the engine is OFF. This is important in case the engine dies while driving, and for stick shifts so you can hold the vehicle still while starting it.