Strange brake pedal
02-14-14, 11:43 AM
#1
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Strange brake pedal
I have a '93 LS400 with 80,000 miles. Its in very good condition but has a strange problem with the brakes. If I hold it on the brakes - say at a red light - after around 10 seconds the brake pedal goes down slightly - 1/2". Apart from this the brakes are fine, I can't see any fluid leaks and the fluid level hasn't dropped in 2 months. Any ideas as I'm stumped?
02-14-14, 01:30 PM
#2
one of my 99's with 236894 miles , is in very good condition, and at a red light when stopped, will start creeping forward, and I have to mash the brake pedal down firmer to stop it, the other 99 with 182828, is also in good condition, and it does not do this. I just dont pay any attention to it. it has never been a problem.
02-14-14, 02:42 PM
#3
Bleed the brakes, could be an air bubble, or a slightly bypassing master, or could also be a small leak in the brake booster system somewhere.
If you haven't bleed to brakes before and don't have a record of when it was last done, you might want to start there. I like to pull at least 250mL through each caliper. I also suggest sucking as much fluid out of the master as you possibly can, before you start bleeding, and the. Fill the master with nice fresh fluid. If you can, remove the reservoir from the master and clean it if there is any crud or black stains/gunk in it.
Also, if there is a lot of black crud is the master reservoir, be very careful as that stuff can rip up your master seals and cause by passing and a crap pedal that no amount of bleeding will fix... You'll have to replace the master.
It's good maintenance to flush the brake fluid every 1-2 years, unless you live in a desert where you can push 3 years if the is zero humidity all year round.
With the brakes properly bled, with the car off, simulate the situation in the driveway. If the problem is gone with the car not running but comes back when running, then it's probably in the booster system somewhere.
But get the easy stuff out of the way first.
If you haven't bleed to brakes before and don't have a record of when it was last done, you might want to start there. I like to pull at least 250mL through each caliper. I also suggest sucking as much fluid out of the master as you possibly can, before you start bleeding, and the. Fill the master with nice fresh fluid. If you can, remove the reservoir from the master and clean it if there is any crud or black stains/gunk in it.
Also, if there is a lot of black crud is the master reservoir, be very careful as that stuff can rip up your master seals and cause by passing and a crap pedal that no amount of bleeding will fix... You'll have to replace the master.
It's good maintenance to flush the brake fluid every 1-2 years, unless you live in a desert where you can push 3 years if the is zero humidity all year round.
With the brakes properly bled, with the car off, simulate the situation in the driveway. If the problem is gone with the car not running but comes back when running, then it's probably in the booster system somewhere.
But get the easy stuff out of the way first.
Last edited by Shmee; 02-15-14 at 11:08 AM.
02-15-14, 04:17 AM
#5
Bleed the brakes, could be an air bubble, or a slightly bypassing master, or could also be a small leak in the brake booster system somewhere.
If you haven't bleed to brakes before and don't have a record of when it was last done, you might want to start there. I like to pull at least 250mL through each caliper. I also suggest sucking as much fluid out of the master as you possibly can, before you start bleeding, and the. Fill the master with nice fresh fluid. If you can, remove the reservoir from the master and clean it if there is any crud or black stains/gunk in it.
Also, if there is a lot of brack crud is the master reservoir, be very careful as that stuff can rip up your master seals and cause by passing and a crap pedal that no amount of bleeding will fix... You'll have to replace the master.
It's good maintenance to flush the brake fluid every 1-2 years, unless you live in a desert where you can push 3 years if the is zero humidity all year round.
With the brakes properly bled, with the car off, simulate the situation in the driveway. If the problem is gone with the car not running but comes back when running, then it's probably in the booster system somewhere.
But get the easy stuff out of the way first.
If you haven't bleed to brakes before and don't have a record of when it was last done, you might want to start there. I like to pull at least 250mL through each caliper. I also suggest sucking as much fluid out of the master as you possibly can, before you start bleeding, and the. Fill the master with nice fresh fluid. If you can, remove the reservoir from the master and clean it if there is any crud or black stains/gunk in it.
Also, if there is a lot of brack crud is the master reservoir, be very careful as that stuff can rip up your master seals and cause by passing and a crap pedal that no amount of bleeding will fix... You'll have to replace the master.
It's good maintenance to flush the brake fluid every 1-2 years, unless you live in a desert where you can push 3 years if the is zero humidity all year round.
With the brakes properly bled, with the car off, simulate the situation in the driveway. If the problem is gone with the car not running but comes back when running, then it's probably in the booster system somewhere.
But get the easy stuff out of the way first.
not too sure about "brack" crud
j/k
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