I always wanted one and got one a while back i havent had it out of the box till this week. I was testing a gas v6 that they think has a burnt valve and or seat. One cyl i put 100 psi in and it held it one of the others i started turning up the presser i got to 30 psi and it all the sudden dropped from holding 30 to 0 . I let off the presser and started over agin but it wouldnt hold any thing and was leaking air into the intake . I am pulling the head off anyway but why did it start to hold then wouldnt hold anything?