03 lq4 out of 2500 pickup, motor is on stand . was doing new patriot dual valve spring when i put 65lbs of air to last cyl on driver side , air is leaking out exhaust port . what is the cause of this . on another site peaple say bad head gasket ,any one have this issue. thanks kevin

 

dirt in the valve seat, same thing happened with some sbc heads i have