Is it definitely my master cylinder?

[IanB]

Did you use an OEM MC when you replaced it? Symptoms definitely point to a bad MC if there's no fluid loss, sounds like fluid is making its way past the seals. It's entirely possible you got a bad MC, or damaged the seals by pumping when dry, pushing the pedal down too far when bleeding, or something stupid like that.

 

[dgoll75]

Did you use an OEM MC when you replaced it? Symptoms definitely point to a bad MC if there's no fluid loss, sounds like fluid is making its way past the seals. It's entirely possible you got a bad MC, or damaged the seals by pumping when dry, pushing the pedal down too far when bleeding, or something stupid like that.

DING DING DING...we have a winner! I picked up the FIRST new MC from Advance Auto friday. When I got back to the project today I rechecked my work which seemed fine and then decided to take the MC back off and exchange it. Well after an argument with the clerk about an not wanting to give an even exchange and paying the difference because I got a 20% discount by ordering on-line, he finally did an even swap. He explained that they have this problem often. On my ride home I called their 800 number to see why the stores can't give/honor the same discounts as on-line ordering they explained the system is being updated and gave me a $30 credit. Sweet. Makes up the cost of the wheel cylinders that I probably didn't need after all. So now everything is done. And I have learned my lesson about not paying extra for better OEM parts in the first place. I certainly will next time.....

 

[LittleCaesar]

Good to hear! Box store replacements parts even considered new aren't always such out of the box.

 

[mccar349]

02 4Runner Master Cylinder Leak

Just wanted to throw some self disclosure out there in hopes one day it will help someone out. Issue I had was my 02 developed a small seep around the master cylinder area. It was almost impossible to track down the source. I would clean the area up, actuate the system and would find nothing. My wife would drive it around, park it in the garage and I would have a puddle the next day. I ended up pulling it out to rebuild the master cylinder and change every seal I could find the P/N for. After rebuilding the master cylinder I noticed one of the reservoir seals was unseated. The reservoir is held on by 3 screws which allows it to pivot just enough to unseat when force is applied. I replaced the valve cover gaskets last week and I'm sure it occurred when I was reconnecting the Coolant Temp Sending Unit connector. So, if you have a leak and performed maintenance recently, it might be worth looking at before you plan a full rebuild.

 

[toverturf]

I'm having this same issue. Pretty much have to put my brake pedal to the floor for it to start braking which isn't the best feeling in the world. I've bled the brakes plenty of times with no air coming out. I just replaced my rear brake drums, shoes, and 1 of the cylinders. Made sure it was all properly adjusted. Only other thing I can think of is the master cylinder. Think it's better to get the rebuild kit or should I spend the the extra $140 and just get a whole new OEM MC.

 

[3bears]

I'm having this same issue. Pretty much have to put my brake pedal to the floor for it to start braking which isn't the best feeling in the world. I've bled the brakes plenty of times with no air coming out. I just replaced my rear brake drums, shoes, and 1 of the cylinders. Made sure it was all properly adjusted. Only other thing I can think of is the master cylinder. Think it's better to get the rebuild kit or should I spend the the extra $140 and just get a whole new OEM MC.

Brakes are one area I dont go cheap...I would go OEM..it will last you another 20 years Im sure you read above where The op was going nuts trying to figure out problem and had a faulty yet new aftermarket. Rebuildling using toyota stuff could work as well. I have rebuilt many ( but not on a 4runner) yet one issue can be is that the bore can get worn over time and new seals will either not seal well, or not last long.

your lucky your master cylinder is so cheap....my new to me 2001, the master cylinder assembly is over 1500...one of the drawbacks of the 2001 and 2002

 

[toverturf]

Brakes are one area I dont go cheap...I would go OEM..it will last you another 20 years Im sure you read above where The op was going nuts trying to figure out problem and had a faulty yet new aftermarket. Rebuildling using toyota stuff could work as well. I have rebuilt many ( but not on a 4runner) yet one issue can be is that the bore can get worn over time and new seals will either not seal well, or not last long.

your lucky your master cylinder is so cheap....my new to me 2001, the master cylinder assembly is over 1500...one of the drawbacks of the 2001 and 2002

Yea I decided to go with a new OEM MC just so everything is new. Didn't want to go cheap and have issues like OP was having.