Master cylinder bench bleeding

I purchased new master cylinder and while bench bleeding as soon as I poured the brake fluid into the reservoir it drains out the front weep hole. I performed step 1 in the instructions but I cannot proceed to step 2 because it won't hold fluid. Back story...I purchased 2 from advanced and returned them because they did the same thing, thought maybe it was a bad lot. I am on my third one, this one is Raybestos brand. Are the instructions missing a step?

 

It's very odd that two of these units were defective . . .
I can't imagine what you could have done wrong in this situation.
Keep us posted with your results.

 

Weep hole you say? Is that the little hole at the very end? Maybe you have pushed the piston too far when bench bleeding. It doesn't need to go all the way in.

When I did mine last year I did the bench bleed at a bit of an angle with a hose going from each port back to the reservoir. I didn't push the piston very far but after a few pumps no more air was seen.

 

It is a little hole on the piston end. We never touched the piston though, took the cap off, put fluid in the reservoir and it came straight out the weep hole. it was the same on all of them. I have attached a picture. The first two it was at the 3 o'clock position (different manufacturer)

 

It is missing the Cylinder Sub assembly. That hole feeds it.

 

Here is a thread about it.
https://www.tundras.com/threads/im-at-my-wits-end-master-cylinder-issues.39933/

 

Oh no, you have the painful one. Thats a horse of a different color.

 

So is the no answer, answer to bench bleed those 2 parts together then attach to booster? Or "bench" bleed it on vehicle using 3rd chamber?

 

The sub cylinder assembly is only available is you buy it with a new master cylinder and brake booster from Toyota. I dealt with this earlier this year. I bled it all together because that's how it comes from Toyota. I threaded some plastic nipples on the holes in the master cylinder, attached clear tubing to them, routed the tubing back up into the fluid reservoir, and pumped the rod (grabbed it with pliers) coming out of the back of the booster back and forth until all the air bubbles were out of the clear tubes. I then installed the whole assembly on my truck, reconnected the brake lines, and then bled the brakes after that.