Help with RMK 700 coolant system pressuring up

[Stickyfingers]

hi my friend just rebuilt his 1998 rmk 700 motor and got it all back together and now when he runs it he says it pressures up the coolant system? he says he bled the coolant system properly. any other advice to give him hes getting pretty fed up with it.

 

[papajake]

lift the front of the sled about 2feet off the ground and run sled at about 2500-3000 rpm. sounds like you have a air lock in the rear heat exchanger