I have a 2003 svtf150 with 75000 miles.But i notice a knocking noise coming under the hood when it's cold and also when I keep the revs at almost 2000 rpm that's cruising speed.I talk to a mechanic and told me it was the lifters need to be replace.I'm been running the truck like that just from home to work for almost a year( its a round trip of 15miles 5 days a week)I don't run the truck hard but I concern about the damage with the lifters not working properly.I'm trying to find a alternate way before I drop the big money on it,any suggestion hopefully will help.Also some friends told me to use additives in every oil change or use motor flushes, in occasions some people told me to use transmission oil,marvel oil,1qt of diesel,etc.

 

is it a "knock" or a "ticking" noise? Lower end or top end noise?

 

It's probably just piston slap which is pretty common if you only hear it upon start up and it goes away when warmed up. In most cases it's nothing to worry about.

Mine did it when I changed to M1 oil and continued until I changed back to MC oil a couple of years ago.


http://www.pistonslap.com/