2001 Gmc Safari Knocking

There Is A Hard Knock Coming From The Engine Until It Warms Up. I Am Starting To Think That There Is A Lifter Or Valve Problem. Has Anyone Messed With The Lifters(hydraulic-I Suppose)? Oil Pressure Looks Ok. Read Some Comments That A Check Valve Might Be Required In The Oil Filter.

Can Lifters Be Serviced Without Removing The Head?

The lifters can be taken out without removing the heads. You have to take the intake off, the pusrods have to be removed, and the lifter keepers have to be pulled, and your there. If you think its a sticky lifter, do a good engine flush, and use a bottle of GM oil supplement when refilling the oil. The oil supplement will quiet the lifter(s) for sure, as long as thats your problem.