Piston Slap

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tvlunn

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I have a question regarding piston slap in first generation 5.4 liter engines?

My 1998 Expedition was purchased new in 1998 and has had the engine oil changed at very regular intervals. On average the oil has been changed about every 3000 miles and the truck now has only 118,000 miles.

I'm guessing I heard the first signs of piston slap when the Expy had approximately 90,000 miles on it. The piston slap only occurs when it is cold outside (maybe 50 degrees and below) and only last for approximately the first 2 or 3 miles of driving after which it goes away. Now that it is summer and very warm outside, there is no indication of piston slap whatsoever ……………… but, it will be back later this fall.

Is this fairly normal in the 5.4 Expeditions?

Is this harmful to the engine OR merely a sign of normal wear and tear?
 

Killer Ride

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I have had 4 Triton motors in 3 vehicles 120,000, 267,500 and 200,000 including my new to me '98 Expy with 172,000 mi. Never had piston slap in any of them. One of the motors is out of a '02 Lightning putting out close to 500hp at 200,000mi.

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1955moose

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Unless somehow one of the skirts got cracked, I too haven't heard of this on the 4.6/5.4 motors. That's not to say it isn't possible. Was the motor overheated badly? That will usually cause it. The more common problem is the cam chain guides breaking down, causing a slapping sound. Either way your looking at tearing into motor if you want to find out.

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tvlunn

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Thanks!

truck has never been overheated. Actually it has been babied from day one and all maintenance has always been done early.

You mentioned: The more common problem is the cam chain guides breaking down, causing a slapping sound. I would imagine this would cause a slapping sound at all times, not just when it was first cranked in cold weather - is this a correct assumption?
 

1955moose

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True, but you'd be surprised how many things cause noise. Question is are you going to tear into motor? Or just fishing for now? Noises usually don't go away. For now keep oil level up, and during the winter take it easy. The heat from expanding is quieting things down as the metal expands. Years back when I repaired and drove two stroke single and twin cylinder Yamaha's, Suzuki's, etc, piston slap was common. Back then pulling a top end apart, and having the cylinders bored, was cheap enough. But these days, pulling apart a 5.4 Ford motor and going through it is the retail price of the Expedition. It may be time to trade or sell the old gal, and move up to a newer low mileage example.

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tvlunn

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Thanks Moose!

I also have a 2008 Expedition I purchased new as well. It runs fine. For some reason I have always liked the 98 Expy and it continues to be well maintained. It really does look almost new on the inside and outside ……………….. never wrecked, no dings, no rust, etc!

From what I've read (whether true or not) an auto with piston slap can run for many years like this. I was simply hoping to get confirmation from someone here with the same issue.
I guess time will tell.
 

1955moose

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As long as the slap is not from a crack in the piston, you'll be fine. A heavier weight oil, say 10/40 might quiet it down some. I know what you mean about liking one vehicle over an almost identical one. We had 2 black town cars back in 2011. Even though the 08 was nicer than the 01 model, the seat was so much better in the older one, that I liked driving the 01 so much more. You'd think the newer 08 should be better, but it wasn't. I guess if the noise gets bad, you'll have to make a decision. For now, just keep an ear out.

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1955moose

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Cracks don't get smaller that's for sure. Piston slap is when theirs too much clearance between a piston and the cylinder wall. It causes a rocking or slapping at the skirt of piston. Sometimes a crack in a piston can go for a while, sometimes not so much. Theirs no real time clock to tell how long or short this problem can go. But like our bodies, if you neglect a problem, say like a bad stomach hurt, or chest pain, the result will rear it's head eventually. Same with your motor.

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I think I have experienced this issue with my 2001 4.6. I can't even call it a problem because it drives fine, and uses no oil, but at times I have noticed a "rattle" when the engine is still cold, but once it warms up it is quiet. I currently have 191k on this and it has really led a very easy life so I'm skeptical that anything is broken.
 

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