I'm having a head removed on my 2004 5.4 3 valve ford f 150.My mechanic told me I should just put another engine in it because of millage an he has to take the whole front of engine apart to put on another head. I've taken care of this truck changed oil like I'm supposed to it uses no oil between changes. I feel no need to put another engine in if this one is not using oil it does have a ticking on the side I'm replacing I was told it was the cam phaser should I replace it while its tore down . Also my mechanic says the book calls for 16 hours labor to do the job does this sound right Thanks for your help