There is a clip that holds this all together if it blew out the clip failed or it over pressurized. If you search the topics here most will tell you they bench bleed these before installation it should help avoid what you encountered. I bench bled mine in the truck by bending a temp steel line that I put in the discharge fitting and then bent around to the fill reservoir I then slowly pumped the pedal while slowly adding fluid until I had all the air out of the MC. Removed the line hooked up to the system line and then bled the brakes beginning with the farthest from the cylinder in line distance. Never had one blow out like that on me. I am sure others will comment but it may be worth a search.