what kind of pressure vacuum breaker did you have? I know the good (expensive) ones do not do this, but the homedepot ones do, example: TORO. Iam assuming that the blowout tee is before the PVB. What kind do you have? You could unscrew the top and check that everything inside is lined up. Let us know!
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers