I've got a '02 SCrew 5.4 that seems to have the "Piston Slap" mentioned in here, although it's only supposed to apply to 2000 and earlier if I read correctly.

It started when it was relatively new, less than 10k. It's got 24k now.

Anyway, it does it on start up when cold, and continues for a few minutes until up to temp. After extended driving, it can be heard again when idling.

It has been given regular maintenance, uses Mobile 1 synthetic oil, and has a Motorcraft oil filter.

Anyone else have this on a newer 150?
What can be done about this?
Will a motor w/ no P.S. have more power than mine?

Thanx,
Vince

 

Okay...When an object is cold, what happens? It tends to shrink. That is, the molecules pull together. When an object is hot, it expands. That is why people use torches to get off a stubborn bolt. It expands the housing of the bolt, making less resitance on the bolt itself. Same issue here. In cold, the piston shrinks. When you fire up the engine, It's cold as well, so You'll have slap until it gets warm, which is when everything expands. Basically, Piston slap is the walking of a piston up and down the cylinder. When it gets warmer, the rings and piston expand, and bammo...The slap is gone. I'd say it's normal, but i'm no expert! Just an apprentice!
Good luck!

 

I've got an '02 supercab 5.4L that I noticed making this noise one cold morning last fall. You'd swear the thing had a diesel! The truck had about 5k miles when I took it to the dealer cause the tires were out of balance and a couple other minor things. Left it over night and picked it up on the way to work the next morning so I could show them the noise while it was still cold. Well, I started it up and no noise. A few days later I realized the error. It makes this noise mainly after putting it in gear upon a cold start.

Few weeks later I left it over night in their parking lot and in the morning went there and clearly demonstrated the noise after putting the thing in gear. They checked it out and when I picked it up claimed that Ford called it a low load phenomenon that goes away after warm up. I replied "duh!" They also claimed that Ford said that it won't affect longevity.

I plan on taking it back again in the fall when it gets cold and insisting on having their diagnosis and the claim that it doesn't affect longevity put into in writing.

 

I have 97 F150 5.4 and I started getting the noise you are describing at about 20k miles. I also took it to the dealer (make that 3 dif. dealers) requesting the problem be fixed and all I got was that motor makes that noise when cold. I now have 165,000 miles on the F150 with the same noise as it did at 20k miles.

 

my 01 F-150 had the slap and valve noise. The GT with the same block 4.6L purrs like a kitten. It isn't normal, but I haven't heard of an engine failing because of the irritating noise.

 

Hey, my dad is having similar problems with his Trans Am, except his sounds like a valve tapping. He's been to 2 different dealers a total of three times and they all say that's normal for that engine and it won't hurt it, but you can't help but worry. We just carried it today again. Does piston slap sound anything like a valve tapping? Does anybody know of a good site for Trans Ams. I've looked for him, but can't find anything like the great sites we FORD truck guys have.