IgottaWoody

I was thinking ABS also...like its causeing a bypass straight back to the resiviour...

kewatin

Thanks for all the replys,i started it up yesterday evening at 4.30 and it did it again.called my local dealer and made an appointment for today. had my neighbor {independent garage next store have look to see if its safe to drive and the first time he checks it ,its fine,second time pedal went to floor. he states the abs module does a self check when starting and the abs module does this in 3 steps ,ie application,brake,release.he said their is definately something wrong.he supects abs module signal where the fluid is being returned to the resavoir,or a bad master cylinder. the car is at the dealership as this is being written so i shall update all to what theissue found was. regards &later KEWATIN

hyperv6

I hope that is it since it is under warranty. It is not one of those things that go bad often but it happens. I see this issue often after some does brakes and they push the piston back into the caliper and not open the bleeder. The old fluid sometimes can hang up a ABS unit if junk gets pushed back into it. This is why fluid also should be changed after a few years. That old black mud we used to get away with today can really damage a system.

Let us know what they find.

kewatin

Well i got the vehicle back at 6 pm tonite,and after talking to the service manager,they say they can find nothing wrong with the system but because it is a brake issue they were obliged to check the complete system. he informed me they had 2 other HHR;S in shop for service and checked them against mine and they are all the same. he exsplained to me that when the pedal is pushed to floor the vacumn is exhausted but the brakes are still in the engauged position & said to me that if they were to push my vehicle with another they would have trouble moving it. he further states that these new abs systems function auto at statup and after inital application pedal returns to proper height.i still feel un comfortable with this explanation as it never did this with my 2009 .time will tell if i keep this vehicle in the near future.
there appears to be no TBS bulletins on this situation so we shall see if any other forum members have a similar problem. tyou members &this web site are a fantastic resource and membership has its rewards.thanks again to all whom responded.regards&later KEWATIN

hyperv6

I would almost consider a second opinion at another dealer. I am sure the brakes are engaged but the pedal I would thing still should not be that low. he may be very correct as I have said earlier todays brakes are very different from what we used to have.

Also you do use your E brake? Even with the miles you have a predal can drop lower with pad wear. I have to use my moms when I drive her car as she never uses hers and the pedal drops.

donbrew

OK, so my case no ABS. Rebuild front calipers, new rotors, new pads, new rear drums, new rear shoes, new rear bearings. Now the pedal will go all the way to the floor AT a stoplight, AFTER the stop. Car stops nicely no lock ups no spongey pedal, just almost no pedal resistance to stop. No bubbles in bleed, rears adjusted good.

The fluid would need to be 15 years old to be "black mud" these days. I have abused and misused my brakes, only using the bleed valves when replacing a caliper or cylinder. I do 70,000 miles a year, and just replace the whole brake system somewhere in the 200,000's and have not seen "nasty" fluid since an old all drum Plymouth back in the 70's. Brake fluid has come a long way since then! All of the DOT3 and DOT4 fluid I see at the parts store is synthetic, recently.

hyperv6

Depends on how the system was maintained. I have seen bad fluid in cases where people top off with old bad fluid that took in moisture sitting in the garage for years. Too often people take an old unsealed half full can and use it when it should have been tossed.

Also more you drive often the better the fluid will remain. Often cars sitting for long periods of time will do more damage to a system than if you drive it. I have seen more cars master cylinders fail just from sitting.

Nearly everytime I have found a car that has been parked for a long time in a garage and put it on the road it has needed brake work and most time a master cylinder.

Driving the car and getting heat into the brake system helps remove some of the mositure or just prevents it from buildng. Once you get enough you can boil the fliuid and the pedal will go to the floor if you really get the calipers hot.

Todays fluids have not changed much till you get to Dot 5
DOT 3, like DOT 4 and DOT 5.1, is a polyethylene glycol-based fluid (contrasted with DOT 5, which is silicone-based). Fluids such as DOT 3 are hygroscopic and will absorb water from the atmosphere. This degrades the fluid's performance, and if allowed to accumulate over a period of time, can drastically reduce its boiling point can create sludge and rust.

Dot 5 can be used but you can not mix it with the other fluids. The Silicone base needs to be all Dot 5.

The difference in the 3-4 and 5.1 is boiling point and not much else.

sleeper

Dot 5 should never be used with ABS.

donbrew

One of my pet peeves has always been "topping the brake fluid off". The level in the reservoir is a gauge of brake pad wear! I do not know ANY reason to add brake fluid, except to bleed/replace it. I have had a brake mechanic ask me "where did the fluid go?"

I do sort of understand replacing the fluid, the moisture thing. Doesn't DOT4, or synthetic deal with that? It has something to do with an alcohol compound in the DOT3, I thought, is that the glycol, is that in synthetic?

Has any modern daily driver experienced boiling, or even overheated brake fluid? NASCAR changes the fluid all of the time, literally. But, the regular guy on the street?

As to master cylinder and wheel caliper/cylinders/fluid lines on cars sitting for YEARS point taken. That stuff can combine with water and corrode gold/silver/tungsten/stainless over time, it is a very awesome solvent/corrosive/lubricant. Almost like battery acid in the brake lines.

I need data! Question asked and statements made are for information gathering purposes only, please enlighten me!

hyperv6

That is why we have 5.1. The 5 was mostly for racers.