So, I purchased a 2009 LX 570 with 120k miles a few weeks ago. While driving home today I noticed that the brakes were becoming soft at stops. Basically if I gradually press on the brakes the vehicle will begin to slow down but the pedal will continue to travel until it almost hits the floor. If I give the brakes a quick pump they will apply more braking force momentarily before beginning to fade again. Since I was driving on rural road, I accelerated and slammed on the brakes, the vehicle came to an almost immediate stop, but after stopping the brake pedal faded again. The brake reservoir is below max fill and is way above min, I have no lights on the dash, and I don't feel the vehicle pulling one direction under braking. I did a little research on the 200-series forum but didn't see where anyone had experienced similar symptoms. Am I correct to assume that my master cylinder is going bad? What should be my next steps?
LX 570 Soft Brakes
- Thread starter ARKginger
- Start date
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Maybe try bleeding the brakes first before you buy a master cylinder. Any leaks anywhere in the system? Master cylinder is not going to be cheap unfortunately. Let us know what you find out.
I have a similar issue with my 2009. I was in the mountains outside of Boise this summer and my pedal went to the floor several times on a descent. Pumping the pedal returned pressure. From my research the seals are going bad in the electric pump in the actuator assembly. I'm wondering if I can 'upgrade' to the 2015 actuator assembly; it has a different part number.
No, bubbles are not normal in the fluid reservoir.
You can find part numbers for ‘09 brakes here. Just confirm when ordering that LC and Lexus are interchangeable.
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- Thread starter
- #7
So I just tried to bleed the brakes, and it wasn't very successful. I don't think there was enough pressure in the master cylinder to move the fluid out of the calipers, but what I did bleed didn't have any air bubbles. I did drive it around some more to get a better diagnosis though. The vehicle will slow down normally when the brakes are pressed, but if you continue to hold down the brakes they will fade. So if I'm at idle or on a incline, I have to periodically pump the brakes to keep it from rolling. I'm not too familiar with how the brake systems on the 200s work, but does this sound like maybe the accumulator isn't holding pressure? I did hear the pump turn on quite often when driving. Has anyone ever replaced anything on one of these brake systems before?
Run a few searches on MUD using appropriate terms like brake bleeding, master cylinder, brake accumulator, soft brakes, etc. After you delve into the results a bit, you may have a better idea of what to ask. How did you bleed the brakes; did you use techstream?
- Thread starter
- #9
I attempted to bleed the brakes by having a helper put constant pressure on the brake pedal while I opened the bleeder. I don't have techstream so I wasn't able to use that. I've read that bleeding needs to be done while the ignition is on but not running, so I assume with a key less start in the LX you just press the start. My helper put constant pressure on the pedal but I was getting very little fluid coming out (different from my experience on other cars) and he told me the pedal was just sinking. Since I wasn't getting much fluid I didn't even attempt the rears. Truthfully, I probably could've tried a little harder, but I felt like the lack of fluid was odd.
So after researching into this some more I would like to say that the master cylinder is failing since I don't seem to be exhibiting the symptoms of a pump failure. I did see a rebuild for a 100 series master cylinder, but nothing for a 200 series (or parts for that matter). I guess I can attempt to bleed the system again tomorrow before taking it into a shop or throwing parts at it.
So after researching into this some more I would like to say that the master cylinder is failing since I don't seem to be exhibiting the symptoms of a pump failure. I did see a rebuild for a 100 series master cylinder, but nothing for a 200 series (or parts for that matter). I guess I can attempt to bleed the system again tomorrow before taking it into a shop or throwing parts at it.
gaijin
GOLD Star
With keyless start, with your foot off the brake, just pressing the Start button once puts the ignition in Accessory mode. To put the ignition in ON mode with the engine not running you have to press the Start button twice with your foot off the brake. In Accessory mode - which sounds like you had - pressure will never build in the brake system
HTH
What he said
- Thread starter
- #13
Bleed the brakes tonight. Went through about two quarts of DOT3. Brakes do feel a lot better. The brake fluid coming out was very yellow so I'm assuming it was dirty. Brakes do still fade slowly unfortunately. From idle and in drive it takes about 20-30 seconds now before the vehicle moves as opposed to previously where it took about 5 seconds. So definitely an improvement but I don't think it will be the long term solution. I'll probably bleed them again this weekend just to make sure
- Thread starter
- #15
Brakes started fading again all the sudden. I was driving around and the brakes were working fine and I made a stop to get some dog food, when I got back in and started driving the first stop I came to the brakes went to the floor and I barely got stopped. The only correlation that I can think of is that it was slightly raining both times this has happened. Is there some potential that there is water entering into the system and causing my problem?
- Thread starter
- #16
So the brakes have not completely faded here recently, but I would still describe them as soft requiring a second pump to brake as strong as I would like. I'm having a hard time finding a functional service manual for the 200 Series, could someone send me the pdf for disassembling the brake master cylinder? I'd like to change out the piston since that seems to help out the 100 series guys that have similar problems
There's a leak in the braking system somewhere. Likely in the master cylinder boost pump unit. Most don't try to fix this unit at the lower levels, rather just replace. There's used units available online.
It's time to get serious about fixing this rather than nursing it along as marginal brakes is a huge liability. While it's possible to DIY fix this, my opinion is it's time to let the pro's do their thing.
It's time to get serious about fixing this rather than nursing it along as marginal brakes is a huge liability. While it's possible to DIY fix this, my opinion is it's time to let the pro's do their thing.
Completely agreed. If you're able to source the right parts and have the ability to service it down to that level, that'd be a huge win. For yourself and the community if you can document the fix. Best of luck!
