I replaced my front rotors on my 99 GS300 and brake pads today, i bled the system how i normally bleed my other cars; Have the wife turn the ignition to on and pump the brakes while i turn the bleeder but to release air. After doing this my rear calipers started leaking brake fluid. What im i doing wrong? This is my first Lexus , but ive owned a Infinity QX56 and bleed the system the same way and had no problems. Thanks.

I believe that my problem is that i turned on the ignition when i bled the fronts and thats what caused the rear to leak. I found this post and its very helpful. https://www.clublexus.com/forums/gs-...-bleeding.html

I don't see how turning ON the ignition will cause any to leak.... Sometimes I turn the car "ON" itself when I work on one. Why you ask? because, some ABS system do not open up. When the vehicle is "OFF" and you try to bleed the brake, you might not be able to bleed that particular line because the valve from the ABS is close preventing the fluid to go through that line.

turning the ignition to the ON position should activate the brake booster on the 2GS....you should hear a pumping sound....like a mini compressor under the brake fluid reservoir....so having your wife pump the brakes to bleed is NOT necessary.

having a leak in the rear caliper is a separate problem. see if you can locate where the leak if from....on the line itself...or at the connection. I suspect it may be a missing crush washer, a loose connection, or even the seals in the piston being worn and requires replacement with a brake caliper repair kit.

good luck.

I bought more brake fluid today and bled the fronts with the ignition off, went to the back and had my wife turn the ignition to on position press one time on the brakes while i bled the rear brakes. Im still leaking from the rear calipers piston seals. I guess its time to replace them, more money!

Glad you found the problem.. That certainly don't have anything to do with having the ignition ON or OFF buddy. It would/should leak even if the ignition is on OFF since your seals are worn out. The seals are cheap. Probably $20-30 and the rest will just be lots of time and labor. Hey, quality time working with your wife right? Priceless!!!!

Tell me about it! I seen the writeup to rebuild the caliper and it doesn't seem that hard. I'm going to the dealer tomorrow to get the kit.

Though you found the problem, your still bleeding it wrong..Im wondering how many pumps before your Booster locks without the ignition on.

Probably a goog idea to repair each caliper's seals....btw, make sure to lube the pistons well.

I replaced my calipers and im still having some issues. I bleed them like then link i posted( Start with the rear passenger with the igniton ON have someone press on the brakes while i bleed , next i did the drivers rear same as other rear, bleed the front passenger with ignition off and lastly drivers front with the ignition off) Im no longer leaking on the rear but the front calipers are sticking somewhat, i can hear them scraping the front rotors while i drive slow and i can feel the car slowing down when i releace the gas pedal. What im i doing wrong? Do these cars have to bleed at the dealer or what? Ive never had this problem, not even my s2000.Thanks

1. still bleeding it wrong

2.Bleeding has nothing to do with Sticking pistons, check ur calipers.

3.Can not compare a GS to a S2k. Specially the POS GS master cyl/abs/booster unit.

You've told me twice that im bleeding it wrong, but not once have you told me how to bleed it. Theres a few members sayign different ways to bleed the GS, the method i used seemed to be the one more comonly used. I really care less on what crappy brake system them s2k has , all i know its stops in a dime.

whos talking about S2k brakes? either way i will now exit your thread cause what do i know. Good luck

Thanks , your doing me a favor master mechanic.

He's talking about the crappy GSXXX's master-cylinder/ABS unit, not the S2000.