I have a 99 4.6 and when starting up cold around 2200 rpms i get a knocking noise not very loud but i know its there.. some ford guys at the dealer said 4.6 and 5.4 had this piston slap problem from the factory??? does any 1 else here have the noise?? it goes away when it warms up a bit! will it get worse? is there anything i can do to fix it?? is it normal on the 4.6 mustangs?? pls help this is really bothering me!!!

 

I've never heard of piston slap from the factory. I have a "engine builder" fvck my motor up because it built it too loose and I ended up with piston slap. Needless to say I'm in the process of redoing my motor, at my expense.

 

I have a 2000 Silverado 4.8L Vortech and has had "noise" since I bought it at 44kmi. Everyone says it's piston slap and that Alum blocks distribute more sound than cast. I disagree. The sound is ridiculous at start up....Like marbles shook around in a coffee can..seriously...Then after 2 or 3 seconds it quites down but never goes away.. I have made my desicion and it is Cam./lifter tap not piston slap like dealer says...Biggest copout of building a ****ty motor.
I think you may be experiencing sticky valves. At 2200rpms, they aren't moving fast enough to notice, but at the same time aren't moving slow enough to not stick and notice. I would reccomend putting some Marvel mystery oil in your crank case and your gas. split the bottle in half for each!

 

Sometimes there is a noise that comes from the timing chains or pistons.to figure out which one it is do the following:
hold the gas pedal to the floor and crank the engine.This shuts off the injectors so don't worry about the engine revving to redline.
Continue cranking the engine until you see an indication of oil pressure on the guage.
Quit cranking the engine and let off the gas pedal and start the engine normally.
If the noise is still there it probably is piston slap,If it's gone,it's more than likely the timing chain/s.
The reason behind this is,cranking the engine until oil pressure shows,pumps up the tensioners (and lifters BTW) but doesn't do anything for the pistons.The pistons will still make noise but the oil fed parts will quiet down.

 

i heard that noise when i first bought my car about 8 months ago and it would be a slight tap right around the same rpm 2200-2500 but now having the car for 8 month i forgot about it cuz i havent heard it. not sure if it has anything to do with synthetic oil i changed twice already. i dunno

 

does this really work?