possible lpop diagnosis question
any help would be appreciated with this. 2003 6.0 excursion. hpop replaced at 140k along with oil cooler and new egr valve. fresh injectors from warren diesal at 180k. otherwise stock. truck now has 225k and in the past month developed a popping noise in the front end at the air intake. this truck has been virtually trouble free other than these issues. the popping noise seems to be air being expelled back into the intake as if an exhaust valve is not opening thus forcing air back out the intake. the truck starts with no problem. the engine runs fine after it gets warm. the engine needs about a 10-15 minute warmup before hitting the road which has never been necessary prior to this situation. btw, i am in south florida. this thing needs to warm up even after it has been 70 plus degrees overnight. mechanic has had a hard time diagnosing this popping sound. the truck runs too good to throw the right code apparnetly but is obviously not running properly. he thinks that the lpop is beginning to fail and that the lifters are not liking the loss of pressure resulting in valve, lifter, rocker arm malfuction, resulting in the popping. this sounds reasonable to me. this particular mechanic has solved many problems for friends of mine that others could not solve. he admits this issue is a difficult one to diagnose. what do you guys think?