Piston Slap

[tvlunn]

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]

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]

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]

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]

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]

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]

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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[tvlunn]

You stated: As long as the slap is not from a crack in the piston, you'll be fine.

This has been going on for about 7 years now. If it were a cracked piston, wouldn't it have already gotten worse by now OR done other damage? Just curious .........… thanks!

Also found this: https://www.f150online.com/forums/v8-engines/8747-piston-slap-information-summary.html

 

[1955moose]

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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[01ExpeditionXLT]

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.

 

[Machete]

You really don’t know the noise is pistol slap. This could many items related to oil, oil pump, pulleys, etc.

What viscosity oil have you been using?
What oil filter?
Oil level proper? Between dots? Top dot? Bottom dot?

 

[tvlunn]

Duplicate

 

[tvlunn]

Duplicate

 

[tvlunn]

You really don’t know the noise is piston slap. You're correct, I don't know for sure what it is. But from a little online research and listening to several videos showing what piston slap sounds like, I feel it is somewhat likely that is what I have. It ONLY does it when it's cold outside and has been sitting several hours and then it completely goes away once the engine has warmed up (maybe 2 or 3 miles of driving). It NEVER make this sound at all if it is warm outside (say 60 degrees and above).

What viscosity oil have you been using? Pennzoil 5W30 from day ONE (and I purchased it new)

What oil filter? Motorcraft FL-820-S from day one also

Oil level proper? Between dots? Top dot? Bottom dot? When I change the oil, I fill it to the top dot. It has never used oil between changes ……...……. that's not to say the oil level hasn't dropped a little when I go to replace the oil, but the level hasn't dropped but just a very, very small amount; basically negligible! ON the flip side, this vehicle has never gone over 4000 miles between oil changes either.

 

[Machete]

Yup but the reason I have a hard time w it being piston slap is the length of time you’ve said you had this noise but no catastrophic failures or worsening of performance.

If it was piston slap you’d have damaged the piston such and scored the cylinders such that you would be losing compression and have significant blow by resulting in smoke and oil consumption eventually fouling the plug etc but you would definitely feel a performance degradation Imo.

 

[tvlunn]

Thanks Machete!

Did you happen to view the link I provided in one of my earlier messages? The following piece of info came from that report:

Will it affect the expected life of my engine?

# Ford claims that the problem will not affect the life of the engine. They claim they have thoroughly tested engines with PS ("hundreds of thousands of miles" according to one source) since the issue arose and have had no failures. One F-150 member has over 100,000 miles on his PS engine and it works just fine. No failures from PS have been reported by members and Ford claims they have had none either.

The more I research this, the more evidence I find from owners of vehicles with piston slap that this may very well be the case in many instances. But, I'm sure it isn't in all cases. I'm just trying to educate myself ………………. and be prepared for what may eventually occur.