Hey quick question I have a 1988 Toyota pickup with an aisin master cylinder. I'm wondering if you guys know what size/thread block off plugs it takes?

Thanks, Andrew

 

I am not real sure just what your talking about.

Just what are you trying to do??

 

Trying to determine if my master is bad or if I have air trapped in the lines. I want to use two little block off plugs that screw in where the brake lines screw into the master. This way ill know if I have a hard pedal my master is good. If the pedal still drops low the seals are blown.

Just trying to figure out thread size I read some where they are two diffrent sizes!

Thanks, Andrew

 

Why don't you just try bleeding all the lines?

 

I did multiple times the first time I let the master run dry. I have bled them so many times since. Two person method, gravity, and vaccum bleeding with no help. Even went back to bleed master cylinder on its own. Im thinking there is a chance I ripped a seal in the master doing all the bleeding? Certainly a learning experience..

Low soft pedal every time I bleed. Thought I may aswell check to make sure master is OK

 

If you can`t find the plugs I just silver solder two nuts closed

 

For future reference if any one searches this topic its M10-1.0

When I blocked the two ports on the master I had a nice high and stiff pedal. I continued to bleed the master on the car with the return lines going to the resivour. No matter how many times I pumped the pedal air kept coming through.

So I pulled the master and attached some photos of what I found! When I then went to bench bleed the master no more air was being introduced?? Should I replace the master?

***Note the booster has been dry there was no signs of a leak. The fluid you see was what spilled out while bleeding. There was all the gunk and some fluid though