master cylinder?

[bagge72]

Hey guys,

I have a 2004 LS V8, and I had a problem last week where it seemed like my calipers locked up on me while driving twice, and I had to sit, and wait about a half hour for them to release. The first time it happened was when I was slowing down to pull in to a parking lot, so the car still would move, but it took a lot more power than normal for it to go, the second time it happend was when I came to a complete stop some where, and then I tried to drive again, and felt like the car was completely stuck. Both times this happened the check advanced track warning came on. Now since that day when this happened, It has not done this again, but then on Saturday while driving my car the brake pedal got real soft, and I had to push it pretty much all the way to the floor for it to work, and then after that I would pump the pedal for it to get back to normal pressure. Then if I waited longer than a couple of minutes to use the brakes again the same thing would happen the pedal would pretty much go to the floor with no effort. I haven't loss any brake fluid so I couldn't really think of what else this would be, then I thought maybe this was a master cylinder issue. So I was wondering if anyone on here had any suggestions?

 

[cammerfe]

For a variety of reasons, a certain amount of brake fluid will disappear over time. Your symptoms are close enough to lost fluid that I believe it's the first thing you should check. Please post back with any further information.
KS

 

[joegr]

Brake fluid doesn't disappear. It goes down for two reasons only.
1. There is a leak.
2. Wear on the pads and rotor causes the pistons to extend out more, thus requiring a higher volume of fluid.

Low fluid or a leak would not account for the brakes failing to release or self applying.


In addition to the master cylinder, the ABS module is suspect.

This is roughly the order that I would suspect possible causes.
1. ABS module.
2. Master cylinder.
3. Vacuum booster.
4. Brake calipers.
5. Brake hoses.
6. Electronic Braking assist solenoid or system.

 

[bagge72]

Thanks Joe, I will check those things out as soon as I get a chance! Unfortunately I work 2 jobs, and train for my fights 5 days a week, and have no garage so it's hard to find time to do diagnose everything. I'm going to have to see if my father will let me use his home garage either tonight or tomorrow night to check it. My father used to run a garage at a used car dealership, and I used to be able to take my car there anytime, because his best friend owned the dealership, but he now works for a new car dealership, and I no longer have those options

 

[Lincoln Jealous]

brake fluid doesn't disappear. It goes down for two reasons only.
1. There is a leak.
2. Wear on the pads and rotor causes the pistons to extend out more, thus requiring a higher volume of fluid.

Low fluid or a leak would not account for the brakes failing to release or self applying.


In addition to the master cylinder, the abs module is suspect.

This is roughly the order that i would suspect possible causes.
1. Abs module.
2. Master cylinder.
3. Vacuum booster.
4. Brake calipers.
5. Brake hoses.
6. Electronic braking assist solenoid or system.

+1

 

[FASTLLS]

+1

Yepper.. Sounds like the problem..

 

[cammerfe]

There is a certain amount of 'leakage' past seals that will be unlikely to leave any kind of stain or mark. Our family has a company that manufactures extra-quality hydraulic cylinders, and I've discussed the topic with the engineers. The reason that there is a refill provision is because of the likelihood of having to do some degree of refill during maintenance.Please don't make absolute statements. Most things that smack of 'always' or 'never' would tend to be suspect. I didn't suggest that low fluid was the only possible culprit.
KS

 

[joegr]

There is a certain amount of 'leakage' past seals that will be unlikely to leave any kind of stain or mark. Our family has a company that manufactures extra-quality hydraulic cylinders, and I've discussed the topic with the engineers. The reason that there is a refill provision is because of the likelihood of having to do some degree of refill during maintenance.Please don't make absolute statements. Most things that smack of 'always' or 'never' would tend to be suspect. I didn't suggest that low fluid was the only possible culprit.
KS

I stand by my absolute statement.
Brake fluid does not disappear. It does not defy the known laws of physics.
It either leaks out, or it fills the extra volume created when the pads and rotors wear down.

I'll also bet that you still haven't been able to run the gen II engine with working variable valve timing from the gen I electronics.

 

[SoonerLS]

There is a certain amount of 'leakage'...

..which would still be a "leak."

 

[joegr]

..which would still be a "leak."

Yes, I'm having trouble understanding the disagreement there too.

Also, different systems have different acceptable leak rates. For car braking systems, the acceptable leak rate is very close to zero. For tractor hydraulics, the acceptable leak rate is much larger. Caliper pistons only have to move back and forth an inch or so. Other hydraulics (like the backhoe I used to have) have to move back and forth a few feet. For that reason alone, they are going to leak some fluid. Maybe that's why the reservoir held gallons of fluid.
My rule-of-thumb for brakes is that you should be able to hold firm pressure on the pedal for several minutes without it sinking.

 

[cammerfe]

Easy does it

I stand by my absolute statement.
Brake fluid does not disappear. It does not defy the known laws of physics.
It either leaks out, or it fills the extra volume created when the pads and rotors wear down.

I'll also bet that you still haven't been able to run the gen II engine with working variable valve timing from the gen I electronics.

If it has gone, in ANY quantity, past a seal, and evaporated, it has functionally 'disappeared'. No one has suggested any disregard for a law of physics. If you've never experienced a necessity to 'top up' a MC in an otherwise working brake system, with no noticeable sign of leakage, you mostly speak to the depth of your own awareness.

I'd also strongly recommend that you re-read my earlier posts in regard to VVT. I've specifically stated that it's my intention to shut off the VVT in the four litre AJ engine I'm building, since it's an extra complication that even the factory seems to find unnecessary in 'boosted' applications.

WTF, WHY THE HOSTILITY, HORSE??? Lighten up!!
KS

 

[joegr]

If it has gone, in ANY quantity, past a seal, and evaporated, it has functionally 'disappeared'. No one has suggested any disregard for a law of physics. If you've never experienced a necessity to 'top up' a MC in an otherwise working brake system, with no noticeable sign of leakage, you mostly speak to the depth of your own awareness.

I'd also strongly recommend that you re-read my earlier posts in regard to VVT. I've specifically stated that it's my intention to shut off the VVT in the four litre AJ engine I'm building, since it's an extra complication that even the factory seems to find unnecessary in 'boosted' applications.

WTF, WHY THE HOSTILITY, HORSE??? Lighten up!!
KS

For the record, I've topped off plenty of master cylinder reservoirs. In all cases (so far) it was due to wear of the rotors and pads expanding the volume of fluid held in the calipers. If you've had to top off due to leakage, then you need to fix the brakes. I suspect, that you had to top off due to pad wear instead.

A leak is a leak is a leak. It does not become a non-leak just because you don't see where it is leaking to or at. My original statements stand. I see no proof offered of them being incorrect.

"Brake fluid doesn't disappear. It goes down for two reasons only.
1. There is a leak.
2. Wear on the pads and rotor causes the pistons to extend out more, thus requiring a higher volume of fluid."

Do you disagree with (1)? (Seems not, you yourself keep talking about leaking.)

Do you disagree with (2)?

Do you feel there are more possibilities that I am missing?
I guess that evaporation is possible, but I don't think that enough could evaporate to detect during the life of a car. Also, it's possible that the fluid level would rise instead. This is because of the moisture from the air that the brake fluid would adsorb.

Why the hostility? It was a long time ago, but you attacked first.

 

[lseguy]

I've had my LS for 8 years and 124k miles. I've NEVER had to top off the reservoir. Ever. In fact, I've never had a car that I've HAD to top off the reservoir.

 

[FASTLLS]

yep.. Brake fluid isn't like water.. Once it starts boiling, it doesn't just evaporate away. Even if it did, you would have to have some dragging brakes or tromping on the brake pedal to keep it boiling to evaporate a noticeable amount.. Not likely..

This is not the problem.. Like stated, leak or wear on the pads and rotor causes the pistons to extend out more, thus requiring a higher volume of fluid

 

[joegr]

I've had my LS for 8 years and 124k miles. I've NEVER had to top off the reservoir. Ever. In fact, I've never had a car that I've HAD to top off the reservoir.

Yeah, it depends on your driving style, driving conditions, and how closely you watch the reservoir.

I'm kind of hard on brakes, so I usually only get around 40/50K miles out of a set of pads, and about twice as much for the rotors. I top the reservoir off when I change oil if it is enough below the max mark to notice. If I waited till it went to the min mark or the light came on, I might not have to top off at all between pad changes. When changing the pads, I always bleed until fresh fluid comes out, so I replace all the fluid each time.

 

[cammerfe]

It's not uncommon, in racing, to use a set of brakes so hard that, in the dark, you can see the rotors glow red. Let me assure you that brake fluid will evaporate. The more severe the usage, the more evaporation you'll see.

I did my first brake job, during high school, probably in 1956 or so. I'll stand by what I've said.

Any fair reader will easily note that I have only made a simple suggestion of one possible factor in the problem outlined above. Your attempts to dis me by mis-stating my comments only tells others about you.

{EDIT}---I've removed my final remark here---It was a little much---Sorry!

Ken Sheffer