Question with brakes

[thibaut]

My brake master cylinder together with the pressure canister was replaced 18months ago with brand new parts. Braking was perfect after the job
After getting my car back from servicing, at idle while waiting at red light, foot on brake at equal pressure, the car started slowing moving forward. I had to apply more pressure to stop it. As I did, the pedal went slowly down towards the floor.
While running, the brakes are powerful and there is nothing untoward.

Servicing didn't involve the brakes as it was mainly routine and also changing steering rack silentblock.
I can't see any leak of brake fluid on the ground.

Any idea what the problem could be ?

 

[nissanh]

still got some trapped air in the system.

 

[Eicca]

With the car off, press the brake pedal firmly 40 times, no less. Get a stopwatch ready. Turn the ignition to ON, don't start the engine. Time your brake booster motor. If it runs longer than 40 seconds (including a few pauses), that's a definite indicator of air still in the system.

 

[thibaut]

Ok thanks. Will run the test. If it does run longer, how do i bleed the air off ?

 

[Eicca]

Ok thanks. Will run the test. If it does run longer, how do i bleed the air off ?

Search this forum. It technically should be done using Techstream software but it is possible to bleed old fashioned style. Just takes patience.

 

[2001LC]

You may have a leak. This could be from a bleeder plugs, ****brake line (flexible or hard line)****, piston seals of calipers or master. Low fluid would be a clue. But so often, fluid is not set properly. So fluid level must be set and watched for loss. Leaks are hard to find if not inspected as leaking. The fluid will dry up if you wait. Unless very bad doesn't show on floor of garage for long.

If brakes not service and this just started very likely a leak. Inspect the brake lines very closely during and after active braking.

Air gets in system one of two ways. System worked on or fluid allowed to get to low (sets off alarm). If fluid old (2 to 3 yrs) moisture builds in the fluid. This can lead to mushy pedal or brake pressure loss with active use. Flushing is the cure.

 

[thibaut]

ok will have a close look. DOT 4 fluid I guess ?

 

[2001LC]

Very Important too Read what is printed on the brake fluid reservoir. DOT 3 or 4 is fine! Toyota fluid is best.