cenozoite

What I'm noticing is that when driving at slow-medium speed, and then applying the brake pedal lightly/moderately, the car will begin slowing doubt as I'd expect it to. But then if I keep the brake pushed exactly at that same pressure, not letting up or pushing harder, then instead of eventually stopping completely as you'd expect, once the car has slowed down to a certain lower speed I can feel the brakes completely "let go" and the car starts rolling forward unrestrained again, even though the brake pedal is exactly where it already was before. And at that point I have to push it down even further in order to re-engage the brakes and force it to stop.

If I just keep the brake pedal where it already was initially to cause the initial slow-down, the car will keep rolling forward indefinitely until it either hits something or runs out of momentum. But the brakes never kick back in and grab the rotors again unless I push the pedal quite a bit further than it already was to start with. The brakes were very recently serviced by the dealership and they say everything is fine.

Does anyone know what might be causing this specific type of issue, assuming it's not normal?

Clutchless

Not knowing your year and mileage, I recommend you have a mechanic inspect your brake system as you do not want it to fail after you have had these warning signs of possibly impending vacuum assist, or master cylinder failure. Or maybe you are just low on brake fluid, or they need to be bleed. In any event, get it looked at before that day comes when they stop working on the second push. I would get a second opinion from another dealer or mechanic.

cenozoite

Thanks. It's a 2009 ES 350 with 96,000 kilometers on it. Funny thing is the dealership mechanics actually just did a full brake system diagnostic a week ago, and the only problems they found were a seized rear caliper (now fixed) and that the brake fluid was in fact *over* filled, so they flushed the whole system and cleaned it etc. I'd have thought anything major like failing components would have turned up in that inspection, but apparently not. I'm going to call them and see if they can recheck it again tomorrow to find the cause of this issue. Hopefully they'll have success. If they don't, I'll try someplace else for sure.

igzy

That's a good call to go back and have them reconfirm the system. This sounds as if there is some air left in the system when you have to re-pressurize it to work (possibly as a result of incomplete flush) or an internal booster leak...

Clutchless

I agree, I think the dealer left air in the system when they flushed the brakes.

cenozoite

Thanks guys.. I got an appointment for tomorrow morning at the same dealer and am going to mention specifically checking for leftover air from the last flush. In general I also have very low/little pressure from the brake pedal overall during the first 50% of its travel distance, and have to press it that far almost every time just to get *any* degree of real response when going at moderate speed. Thinking it's all related to the same issue, so will describe it all and ask them to recheck thoroughly. Fingers crossed it's an easy fix and will report back with findings afterward.

ESh

Clutchless

I bet they were sloppy and did not do a good job bleeding after replacing the brake caliper. Or did not bleed it at all...

cenozoite

So I went to the dealership on the weekend and they checked the brakes over and said everything was perfectly fine and functioning normally, no air or other problems found. That said, they did flush the brakes for me again at no extra charge, and the problem hasn't recurred again since then, so.. draw your own conclusions I suppose about the first time. Fingers crossed that's the end of it... thanks for all the suggestions.

ESh