Brake master cylinder
 

Recently had squishy brake pedal, Bleed system and good for a couple miles and back to squishy. Inspected system and no leaks visible, so with no further testing bought MC and replaced. The MC I am replacing is an Aisin and does not appear old, it is older then the 3 years I have owned the vehicle, but of unknow age.

Replaced MC, bleed and everything seems ok. But out of curiosity I pulled the old MC apart. The first piston came out with no issue, the 2nd one would not budge. I drilled a hole in the end of the MC and had to beat the 2nd piston out with a rod and hammer, did not come easy.

I don't think that the MC just froze up, that it was good one day and not the next, could be wrong?

My question is if the MC was frozen for some time, why did I not notice anything and is there anyway to check for this condition? Expiring minds need to know.

This is a 93 V6 Cab and Chassis, automatic with a Sea Breeze RV attached to it.

93 Toyota replacement fuel tank issues.
 

Ended up in wrong place and do not see how to cancel?

Yes, thank you. Did not look like it interfered with piston?