Hello,

The other vehicle, a 97 Sunfire, has developed really spongy brakes on Saturday.
I could not find a leak to cause this.. We really had to pump the peddle to get some pressure built up..

I brought the car to a mechanic that Saturday and he got to it Monday morning.. He told me he drove it all over and could not find anything wrong with the brakes. He also said he put it up on the lift and could not find a leak.. He did adjust the back brakes a little although he said they were pretty good..

What do you think? Is it possible that nothing was wrong? I doubt it.

I know he isn't trying to pull a fast one.. He could have started replacing stuff blindly..

Jeff

 

everytime i drive my work van and then go to my monte i feel a difference in the breaks.going from one car to another ....

are you driving 2 cars one after the other?......
my van is spongy my monte is alittle bit harder

 

I wish it was that.. They were always a little softer... My wife noticed it, and she is used to that car..

I have to put it to the floor to even stop it when backing out of my driveway...

Thanks,
Jeff

 

Probably the power brake booster thing... or whatever it is callled.

 

I thought about that... When I pick the car up tonight I will see how it feels on the way home.. I believe the assist is done via vacuum... If that was the case I would guess that the pedal would be harder to push.... I am going to see if there is a vacuum leak though..

 

Your thoughts are correct on the fact that your power brakes are assisted by vaccume, and that if your booster or your lines were bad your pedal would be hard. So dont start there, is there any lights on like the abs or otherwise on the dash? The other possibility is that your brake fluid my be overly contaminated by water and my be heating up too quickley, and possibly caused the water to boil and cause some air to be in your brake lines. a way to checkcontaminaton of your fluid is to use a digital multimeter and set it to the 20 volt DC scale, put the positive (red)probe into the brake fluid and ground the negative(black) on a good ground. If your meter shows .03 volts or higher this means that your fluid is 30%(.03v) or more contaminated based on the reading (eg. .05 means 50%). If this is the case it can cause braking difficulty on the other condition I spoke of. This would be a good place to look and can explain a spongy pedal, which usually means air in the system, from the water which doesnt react the same as brake fluid under pressure. Just so you know if there is water in your lines doesnt mean that you have a leak. Brake fluid is hygroscopic, meaning that is absorbs water naturally, so it can do this through the cap since it does vent a little. And so you know the reason that you will get a volt reading without and battery power os because the dis-similar fluids will cause electrolisis and will naturally create some electrical voltage.Good luck, hope that this was heplful.

 

Hmmm I have done a multimeter test on antifreeze to see how acidic it was.. I didn't know you could do a voltmeter test on brakefluid... Interesting...

I just googled it and did not find anything except one book..

I will have to check this out.. I was tempted to replace the fluid just in case it has broken down with age..

Thanks,
Jeff

 

My Volt Meter read .02 volts on the 20V setting...

 

well taht would mean that you have about 20 percent contamintaion of water in you fluid, dependong on age it might be a good idea to flush it out anyway. Do you have any brake lights on in you dash? I would suggest a bleed/flush of you system and go from there. If your doing the work yourself its probly the cheapest place to start, and if there is any hard braking done it is still possible that you have some air bubbles. I would start there and then check adjustment of your rear brake shoes, assuming that you dont have disc in rear which most sunfire/cavalier's dont. Your rear shoes are what give your pedal the height it needs, if you need an explanition on how that works I can give you one jsut let me know. These two things, flushing and adjusting the rear shoes would be the most cost effectiveplace to start, if neither of these work and you cant find any leaks I would suspect the master cylinder has some internal laekage. But start there ans see what happens you might be surprised, and a spongy pedal usually comes from air in the system. Check em out let us know what you find.