Brake bleeding problem - one line will not bleed

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timsch

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Aug 24, 2011
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Brookside Village, Texas
I am trying to replace the brake fluid in my 2008 Sienna LE. I am able to crack the bleed fitting on three wheels and have fluid flow out the fitting as someone pushes the pedal to the floor, but on the right rear, there is something stopping the flow. I crack the fitting while my wife is pressing on the brakes and I get about two inches of fluid (VERY SLOWLY) into the tubing connected to the tubing before the flow stops. The pedal never goes to the floor no matter how hard she presses the pedal. I have verified that the fitting is not clogged.

I know on older cars that the proportioning valve could cause problems like this, but I don't know if that is still a possibility with modern vehicles.

It is curious that I get some flow initially and then it stops. Since it does flow, if nothing else is stopping it but some type of constriction, it should still slowly flow until the pedal hits the floor. So I wonder if there is not some other component that is stopping the flow.

Anyone else know about this issue?
 
Try bleeding both of the rear wheels with the ignition key in the on position in case there is an electric accumulator pump in the rear brake system.
 
Remove the bleeder, it may be clogged.

I don't think these cars require techstream for bleeding.
 
He said he verified the bleeder is not clogged.

If that's the case, I recommend removing parts until the blockage is identified and taken care of.

Start with removing the cylinder/caliper and see if the brake fluid flows through the brake hose. If you get flow, then take the caliper apart.
 
Yeah, I already tried bleeding with the bleed fitting removed. I was surprised that NO fluid flowed without the fitting installed. I thought perhaps there is a shutoff that closes when the fitting is removed on this vehicle. Again, I had slight fluid flow initially when the fitting was installed and cracked 1/4 - 1/2 turn.

I'll start removing components to diagnose soon, but I wanted to run this by the the forum gurus before overlooking some simple fix that is unique to these vehicles. I just got it a week ago, so don't know much about it yet, and I've never had a vehicle with ABS before.

edit: noted that this vehicle has ABS
 
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Try bleeding it with the car running, the vacuum booster will give you more pressure to blow out whatever is clogging it.
 
My money is on a collapsed brake hose. I'd bet a quarter, but with my screen name, not any more than that.
 
Originally Posted By: timsch
Yeah, I already tried bleeding with the bleed fitting removed. I was surprised that NO fluid flowed without the fitting installed. I thought perhaps there is a shutoff that closes when the fitting is removed on this vehicle. Again, I had slight fluid flow initially when the fitting was installed and cracked 1/4 - 1/2 turn.

I'll start removing components to diagnose soon, but I wanted to run this by the the forum gurus before overlooking some simple fix that is unique to these vehicles. I just got it a week ago, so don't know much about it yet, and I've never had a vehicle with ABS before.

edit: noted that this vehicle has ABS


Did you try it with the ignition on? If the system has a proportioning valve and electric accumulator pump (which some Toyotas have) then you need to activate the pump. 4 Runners do the same thing you are experiencing unless you turn the ignition on.
 
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Originally Posted By: tightwad
Originally Posted By: Kestas
He said he verified the bleeder is not clogged.

If that's the case, I recommend removing parts until the blockage is identified and taken care of.

Start with removing the cylinder/caliper and see if the brake fluid flows through the brake hose. If you get flow, then take the caliper apart.

My money is on a collapsed brake hose. I'd bet a quarter, but with my screen name, not any more than that.


+1 and hahaha!
 
Timsch, are the pads on that wheel worn equal to the pads on the wheel opposite it at the same end of the car? If these pads are worn less, you know that this brake isn't working as it must. If the pads are worn equally, you have a real head scratcher here. Pls let us all know what you discover.
 
Doog, I haven't gotten back to attempting to bleed it again yet. I'll try to bleed again this weekend with the ignition ON (engine off). If that doesn't work, I'll start taking things apart, checking pad wear, etc.

I'll let y'all know how this turns out. I have my fingers crossed that it is an issue with the ignition being off. That seems the most likely given the clues.
 
keep the engine running, otherwise you will be entering another topic "My car does not start; is it battery or alternator?"
 
My 26 cents is on the flex line. Seen it many times. If this is not fixed, sooner or later the caliper will freeze causing the caliper or cylinder (depending on disk or drum) to stick. They might not be collapsed, but the inside of the line will form tiny rubber balls which collect causing an occlusion of the line.
 
I finally got time to dig further into this. I did turn the ignition on and this did not make any noticeable difference. I pulled the calipers off and pressed the pistons back into the housing with a c-clamp. I did this on both the right & left rear calipers. I held the problem piston open with the clamp while my wife pressed the pedal. The good piston came out and the pedal went to the floor. I reversed my setup and when she pressed on the pedal, the piston hardly moved. She pressed harder with both feet, but it still hardly moved.

I should note that the problem side piston was very easy to push back into the housing with the c-clamp. This indicates that the blockage is only in one direction, which lends credence to Michael P's suggestion that it is possibly bits of rubber in the ID of the flex-line. The fact that I can bleed a small bit of fluid initially, but then no more after that is consistent with a somewhat flexible blockage.

I want to be pretty certain about what I'm doing before going further, because once I break open the lines any further, the car is not going to be driveable until I fix it.
 
make sure the brake hoses are not twisted.I cant see an 08 anything being wrong with the hoses.
 
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On older Tauruses the rear brake lines would clog shut where the metal clamp went around the hose and would cause this. Though they had a lot more years/miles on them

I always keep the engine running so I can use the vacuum boost like said above.
 
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