Potential brake issues I'm a bit scared

[Hoff Daddy]

So, I drive a 99 4dr LX f23a1 accord with a rear disk brake swap. That is the only thing I've ever done to my brakes and all that seems solid, my car stops pretty good, very smooth. What is scaring me is that even before my disk brake swap, my pedal feels solid as a rock in the cold. The fluid is full now, I've never had to add and it was flushed 10000mi ago for a front brake job and very recently for my disk brake swap. I've talked to a professional and he said that sounded pretty bazaar. I suspect it's the 3 old rubber brake lines being bad and contracting in the cold or something like that. The other problem is pretty recent... I found it out sliding backwards on my steep driveway on ice and I locked the brakes and spun myself around instead of sliding back into a tree. My brake pedal will start to hiss if you give it a lot of force and once it starts to hiss you could probably just push it straight to the floor. The car has no braking problems in normal weather under normal circumstances.

 

[RedRyder]

Inspect your lines and booster

 

[DarkSideAccord]

sounds like the brake booster acting weird, esp if u drained, refilled and bled the system

 

[james'99]

Inspect booster for sure.

 

[Hoff Daddy]

So I inspected the booster, did the 3 tests, it looks normal. The only thing I think is weird about it is that I can put the pedal straight to the floor. There's a lot of pressure at the end but you can definitely do it and it makes the hiss when you do it. With the car running I can't push the pedal to the floor, but it's really close. This just seems odd for having all new brake pads, but my rotors are close to minimal thickness, I know because I had the back turned. So, to my surprise, the booster is good, or it at least works. If there is a problem it has to be some sort of pressure leak. I should probably replace the rest of my brake lines, but would a leaking seal in the master cylinder be likely? If I let the car run and I stand on the pedal it doesn't move. I'm stumped, or everything is fine and I'm just crazy.

 

[xci.ed6]

with the car off, push and hold the pedal with constant force, does it sink lower?

if yes it leaks

or does it feel 'spongy'?

if yes it has air in it

 

[Hoff Daddy]

I didn't try with the car off I did it the same way as I found out the master cylinder leaks on my 72 Dodge dart, but it has manual brakes. I didn't think about that, the brake booster would make up for the lost pressure, sort of. So I can check the brake booster off the list. It's not spongey, when I said I've flushed the fluid I mean I wasted a ton bleeding the brakes 5-6 times.

 

[xci.ed6]

k, no air...

but it sinks, so there's a leak somewhere, sometimes out the rear master cylinder seal. Pop it loose from the booster, you don't need to pull the lines. You can pull out enough, barely enough, to see the back of the master, look for any fluid. I type this assuming you followed -EVERY- other line. From start, to finish.

As quickly as you make the pedal seem you should be loosing ~1 fl oz of DOT3 every time you press the brakes!

 

[Hoff Daddy]

k, no air...

but it sinks, so there's a leak somewhere, sometimes out the rear master cylinder seal. Pop it loose from the booster, you don't need to pull the lines. You can pull out enough, barely enough, to see the back of the master, look for any fluid. I type this assuming you followed -EVERY- other line. From start, to finish.

As quickly as you make the pedal seem you should be loosing ~1 fl oz of DOT3 every time you press the brakes!

I don't lose any fluid it all but I will definitely check. If it has a leak in the master cylinder it's probably just like my dart. The dart doesn't lose fluid but it loses pressure bad, if it had fluid leaking out I'd be screwed.

 

[xci.ed6]

well, any loss in pressure is a leak.

Any 'spongy' is air.

Think of a hydraulic system, it's basically a direct mechanical linkage. Air can compress. Hydro is direct.

I need a picture, I guess I can work on one later, but just to try to pass the message for now. Try to visualize it