gpratt

Ok I have a 91 accord ex,My Stepson pulled the right front brake calliper apart to check the pads to see if they needed to be replaced for me.He had a book to follow on how to do it,But he decided to do it his own way wich was wrong.Ended up not needing pads wich was good.But instead of screwing piston in like he was suppost to he compressed it in.Now i getting a spongy brake pedal some of the time.you might drive it all day and have a good firm brake pedal then all of a suden very spongy to almost no brakes at all.And when it does get a spongy pedal i hear a noise like a buzzing sound coming from under car when it does this.What kind of damage could he have done by compressing the piston into the calliper?I have bled the brakes and this has not not worked still same problem.

Stagerguy

I thought you were suppose to compress the piston, not sure how you would screw the piston back in. Can't offer much help on the sponginess, buzzing may be the ABS (if it has ABS).

MNMike

I've replaced the brakes on my 92 accord a good number of times and compressed it every time - no issues thus far.

If you've bled the lines already you can check that the caliper slides (pins) aren't sticking. Otherwise it could be a leak in the master cylinder.

dohctor_B

Did your stepson open the bleeder valve when he compressed the piston? When you compress the piston in a pressurized system and the bleeder valve was not open or the master cylinder cap was not removed, the fluid still needs to go somewhere.

The fluid could have been pushed back though the master cylinder and had no where to go, causing an internal leak in the cylinder.

Do this test. Start the car and stand on the brakes, not extremely hard but firmly. If the pedal slowly sinks to the floor then your master cylinder is faulty.

If it's not your master cylinder that is the problem, I would bleed the brakes again very thoroughly and trouble shoot from there.

Turbod Fullclip

This would have been extremely helpful about a year ago with my brakes. However, my situation differed in the fact that when i compressed my piston without opening bleeder or master cylinder cap my brake pedal was spongey for about a night and stiffened. This is most likely because the brake fluid forced into the system pushed my brake fluid overflow cap off and forced its way out all over my garage floor. i also bled the lines twice to make sure all air was out. Try bleeding the lines once more.

holmesnmanny

lol You don't "screw" pistons back in you just compress them. Also, you never ever have to open the bleeder valve to compress the pistons in. You just need to open the master cylinder cap. The braking system is designed to essentially give you an idea when you need to change the pads since the fluid will get low. Most people just put fluid in not realizing it's not necessary. The only possible way your brakes would be spongy now is if he tried to bleed the brakes and didn't do it right.

This time just have someone pump the brakes and hold it. Then open the bleeder valve. The pedal will hit the floor. Then close bleeder valve. Do this about five times making sure that the master cylinder doesn't get low. Then on the last one, have them pump the brakes and hold it but this time open and close the bleeder valve so fast that the pedal does NOT reach the floor. This will ensure that no air gets into the very end of the caliper by the bleeder valve. See if that helps.

MAD_MIKE

Overstroking(flooring) a used MC will fail it.
After some time crud and corrosion will build up in the area of the MC bore that is not normally traveled by the pistons inside the MC. This area is rough. If the pedal is depressed past its normal travel the seals may be damaged causing an internal MC leak. This can cause a random dropping or dead pedal.

gpratt if the pedal was floored after the pad check to push the pistons back out, what you may be experiencing is the above mentioned issue.

holmesnmanny

Mike what in the hell are you talking about dude ? Im at a complete loss for words as to what in the hell you just said.

holmesnmanny

Im talking about bleeding the brakes I have no clue what ur referring to.

Hidenplanvew

When you compress the piston in the caliper the pistons in the MC are in a open state which means only way it would damage a MC is if the feed line from the res line would be blocked. Even with the cap on, the seal will allow fluid out.. When you get fluid on painted surface, make sure to flush with water or paint will peel off.

tim73

A better way is to compress the rubber brake line, there at the caliper, then open the bleeder and compress the caliper. This opens up the caliper, and doesnt send back a bunch of brake fluid to the master cylinder, which can overextend it, and make it leak internally. IE spongy pedal feel. But, get yourself a brake bleeder(Theyre cheap), they work better than the old pump up, crack open bleeder, allow pedel to go to floor then close bleeder method.

holmesnmanny

I know that, the only reason I say leave the cap off is so that you can see the fluid and that you won't have the cap shoot off.

MAD_MIKE

Normally, when you depress the brake pedal there is a given amount of takeup needed to actuate the brakes.

If the pistons in the caliper were pressed back into the caliper and the old pads were reused, there would be an excessive amount of takeup needed to bring the pads back into contact with the rotor. Requiring flooring of the MC, same if the brakes are bled and the age of the MC is not taken into account.

When the MC is older, the pistons inside the MC only travel a certain amount due to the closed system, and incompressible brake fluid. This keeps that area normally traveled by the pistons free and clear of crud and corrosion. Beyond that normal travel the MC bore will acquire a build up of crud and corrosion. The surface will be rough. If the pistons travel on this rough surface the seals may be torn or damaged. This would cause a random dropping or dead pedal.

This is nothing new. It is why it is best prior to bleeding brakes to check where the normal travel is, and to prevent flooring the pedal by placing something, such as a block of wood, under the pedal to prevent damage to the seals.

holmesnmanny

Im not even asking him to compress the piston. Why would i seriously ask him to do that ? Even if I did, so what ? I don't get why you think that's a big deal. This is how brakes are "normally" bled. Yes, you can use a vacuum pump and make it a one-man operation at the caliper, but most people don't know how to do that.

gpratt

I re bled the system yesterday it had a good hard pedal for about 30 minutes of driving.Then pedal got spongy again and soon it was all the way to floor.So I should replace the Master Cylinder?When I was bleeding the the system the Calipers seem to be responding fine to the compression of the brake pedal.Also there has been no loss of brake fluid or signs of any leaks.

MAD_MIKE

Didn't say you did. gpratt stated his stepson did.
Normally you would not want to floor an MC that is not new.
Over-stroking an MC will have the seals ride on a rough surface. Combined with new brake fluid(especially if the brakes have never been bled) can exacerbate the problem by swelling/softening the old seals, making them more susceptible to being damaged.

This is also why you replace wheel cylinders when replacing drum shoes. New shoes with more material will require the pistons and cups to be depressed back inside the wheel cylinder housing. Since this part of the bore in a wheel cylinder has not been traveled on in quite some time, the surface will be rough, and not allow the cups to seal. Rather than risk having a leak, the wheel cylinders are just replaced.

If you cannot find any leaks or wet spots then it most likely is an internal leak of the MC.
When bleeding the brakes, there is little pressure being built up in the system.
Combined with the engine off, you are not able to create the same pressure in the system with the engine on due to the boost assist.
If you cannot find any leaks, wetspots, or swelling hoses, it more than likely is an internal leak in the MC.

gpratt

Ok I thank you all for the information. I will investigate more on the car.My thoughts are that it was probly the M.C. just strange that they are not spongy all the time.Just after you driven it for about 30 miles it starts getting spongy.

vcbynature

You may want to inspect the brake hoses at the calipers they may be cracked, also how's the condition of the brake fluid? When was the last time you had a brake fluid flush? Over time the brake fluid will start to brake down and if the pedal gets spongy after hours of driving, sounds like the brake fluid is thinning out when it gets hot.

gpratt

I have only owned the car for a few weeks.I bought it from the original owner.The car had set up for about 2 years the old lady that owned could not drive any more so its been parked outside in her drive way.So as far as I know its never been flushed.

gpratt

Ok I have replaced the master cylider and flushed the system.The brakes are working great now.I would like to thank you all for the info you all gave me.