Brakes got really soft last week & I found the rear passenger brake shield coated in oil.
When I removed the drum I found a black, gooey mess. I couldn't tell if the oil was brake fluid or axle lube since it was mixed with brake dust. The T4R has 233K miles so I drove over to my local Toyota dealer & bought a new inner oil seal for the axle.
I also ordered a set of brake shoes & wheel cylinders (always change in pairs) since I wasn't really sure where the leak was coming from and didn't want to take a chance on fouling the new set of brake shoes.
While I was waiting for parts to arrive I removed the axle and found a non-OEM inner axle seal that didn't have a steel shell, it was all plastic. I figured that this was a repair by a shop using off brand parts and the cheap seal just failed. So I R&R'd the seal & installed the axle.
When the parts arrived I cleaned everything up well, installed the new shoes & cylinders and bled the system with the
Allstar one man bleeder.
Then I ensured the drums were adjusted correctly using the parking brake fine tuning after the initial "just starting to drag" installation procedure of the shoes.
When I test drove it the brakes were soft and when stopped the pedal would easily go almost to the floor. If I pumped them up and held pressure on the pedal the pedal would get tight & then slowly collapse to the floor.
So I ordered a new
Advics (Asin) OEM replacement master cylinder from Rock Auto. When it arrived I bench bled it with
this kit at Amazon and then installed it with a new Toyota gasket and then bled each corner with 40 pumps.
On the test drive I found the pedal to be somewhat soft although the sinking pedal of the 27 year old original master cylinder was cured so I took it to a dirt rode and activated the ABS about 10 times to purge old fluid and possibly trapped air - brakes back to normal.