Hello,

I recently changed both rear calipers on my 2005 TL AT. At the time, I only had two jacks, so I only lifted the rear. After bleeding (1 person bottle method) the rear two brakes, the pedal was hard with the car off. With the engine on, the pedal was soft.

I got 2 more jacks, lifted all 4 wheels and bled all 4 calipers. Again, with the engine on, the pedal was soft.

Three years ago, I flushed all the brake fluid and bled the brakes with no problems. Pedal was firm and normal until I replaced the caliper. I've checked the lines, ABS module, master cylinder, and calipers for leaks.

Some questions

1. Could a defective new caliper (rockauto) cause a soft pedal?

2. Can air even enter the ABS system if only the rear was jacked. I could not measure exactly, but it seemed as though the high point on the jacked rear hard line was equal in height to the ABS module.

3. I made the mistake of turning the key to the 2 position when bleeding the first time (I did not turn on the motor). Could this have cycled the ABS and sucked air backwards?



Thanks for any ideas. I’ll probably try to gravity bleed brakes tomorrow, and tap on calipers to loosen any air pockets.

 

You should try re-bleeding the brakes and do a brake fluid flush at the same time.

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Thanks. This one has me stumped.

I've flushed over 40 ounces in the last several days. I've done the rear once alone via pedal method. Then did all four once via pedal method. Then today gravity bled all four. I've tapped the calipers to loosen any air pockets. I have an autel 808S due on Wednesday. I may wait until then and try the ABS bleed function, but I just don't understand how air could have entered the ABS module. If I had removed the front right caliper I could imagine how air entered the ABS module. I studied all the ups and downs of the hard lines today and cannot see how air would have made its way to the ABS module from the rear, especially as it was jacked up.

 

Think about the master cylinder?

 

Thanks for the reply.

The MC was my last item to investigate. Everything worked well before the caliper change so I figured the MC was good as well. I looked for leakage around MC and found none. I read the internal seals can fail, but I also used a wood block under the pedal to prevent too much movement of the MC (some posters claim pressing pedal to floor can damage the internal seals of the MC).

Before running the ABS bleeding function on my new computer, I figured I would remove the calipers
1. to check the pistons for leaks and
2. to bleed the calipers with the bleed screws at the very top.

I found brake fluid inside the caliper piston and running down the bottom the the piston.

I'm pretty sure fluid is not supposed to be there. Can anyone confirm?

 

You're not supposed to see any fluid anywhere.
While you're at it install these speed bleeders. It's the best one man bleeding system ever. And you don't have to explode your master cylinder and blow its brains out by pumping it up..
just press once, and the fluid comes out on each compression stroke. 1 stroke, 1 squirt. haha... simple.
you may have to e-mail them to get the correct part number..
Speed Bleeder Main Page