Dealer describes "Piston Slap" as a "Normal" characteristic of the 5.0 V8

[ice445]

This is my first V8 so I'm getting used to what the engine sounds like. The noise was not present prior to 400 miles. However, I do acknowledge that it is colder now than when I got it in October.

It was always there, trust me. You just didn't notice it until then. With these motors, seems like it's easier to blow it up then get anything that may be wrong with it fixed in advance. I suspect the dealers are extra averse to noise complaints, since they can have a tech waste tons of hours on it just to not fix it. Plus Ford doesn't want to pay anymore until it's knocking or blown up anyway.

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[Pittpa]

So I had my GT into the dealer yesterday for engine noise. I provided the bulleted information below to the dealer describing what I hear, when it occurs, the conditions for occurrence etc. The technician stated, "That the noise is normal and all GTs have them." When I asked what causes the noise, he specifically stated that it was "piston slap" and that "occurs with all 'high-performance' engines."

So when the dealer wrote up the ticket for the service visit, they first put, "[Tech] spoke with customer and salesman. Compared to 2 other new mustangs and it is a normal characteristic of the vehicle."

I asked them to rewrite the ticket to specifically state, "Noise described to customer as piston slap".

Ford then rewrote to state, "Lower end piston slap noise."

So this is a semantics game on my part, but "Lower end piston slap noise" is not quite the same as "Lower end piston noise described to the customer as piston slap."

Any thoughts on this?

When I look up articles discussing piston slap, they all tend to state that it is something that should be corrected by the dealer.

• Starting approximately 1700 rpm, there is a “rapping” sound that can heard. It sounds almost like a hammer hitting a metal plate very rapidly.
• Sound generally present around 2K rpm and when cold (i.e. not at full operating temperature), the sound can be heard up to almost 3K RPM.
• Sounds like it is coming from the passenger side of the car.
• Sound occurs when going from no throttle up to low throttle (about 1 quarter pedal movement).
• Sound also occurs when coming down off the throttle and transitioning through the low throttle to no throttle.
• I can make the sound at will, meaning if I hold “maintenance” throttle to maintain speed or adjust the throttle to a certain point, the sound can be heard.
• The noise isn’t as apparent at higher throttles, but it can still be heard.
• After the car has warmed up (that is, when at normal operating temperature) the sound it a bit more intermittent, meaning it sometimes does not seem as apparent, but other times it is present when at operating temperature in the noted rpm ranges.
• Oil appears to be at the normal level on the dipstick.
• Sound has been present when using either 87 octane or 93 octane with no apparent change in the sound.
• The “rapping” noise as described began at just over 400 miles and was not present prior to then.
• RPMs were kept relatively low (less than 5K) and was not redlined during the break-in period. (miles at drop-off were 1177.)

Here is mine FWIW

 

[StangTime]

Here is mine FWIW

Is that happening around 2K RPMs? If so, then this is what's known as the 2K rattle.

 

[gmupatriot]

Is that happening around 2K RPMs? If so, then this is what's known as the 2K rattle.

Yes. I have 53,000 miles on my GT and have heard this sound from since I bought it new.

No idea if there is damage to the engine because of this though.

 

[Pittpa]

Is that happening around 2K RPMs? If so, then this is what's known as the 2K rattle.

It is the 2K rattle. I’ve been meaning to change the title of the clip.

 

[EFI]

I've talked to a couple of other techs and its not uncommon for the 5.0's to break pistons and skirts apparently.

How the heck do you break a piston skirt?? Thing those techs just like to hear themselves talk.

 

[Pittpa]

How the heck do you break a piston skirt??

Ask these guys.

https://duckduckgo.com/?q=Mustang+5.0+broken+piston+skirt&ia=web

 

[Angrey]

Are the gen 3 pistons forged or hypereutectic?

 

[Garfy]

I agree. The dealer service tech also stated it was piston slap. So their statement that it was "normal" doesn't seem to be correct.

I guess what the tech meant is that if it is piston slap, then it's "normal" in that it's exactly how piston slap sounds like. But it's NOT normal to have that sound in your engine. BTW, I've only got 3800 miles on my engine but I've NEVER had the "2K rattle" in my engine, though I've heard the "tick-tick" noise that's probably coming from the DI injectors when they actuate because it sounds like every other DI engine I've heard, from Honda "Earth Dream" engines (all DI) and Hyundai/Kia models as well. Of course I don't hear it all the time as they don't operate all the time (I don't know when the PCM activates the DI or port injectors under what operating conditions.) Due to the very high fuel pressures in DI systems, the injectors are very loud compared to conventional port injectors that run between 30-50 psi (old models vs. newer port models).

 

[paulm1]

Pistons slap has been going on for decades on Gm engines and has not been detrimental to longevity
I had a 8.1 that sounded like a diesel when cold

Nissan vq40de also. 2005-2021

 

[ice445]

Are the gen 3 pistons forged or hypereutectic?

Hypereutectic alloy. Rods aren't forged either but they are dimensionally pretty stout, and the crank might as well be bomb proof lol

 

[Angrey]

Hypereutectic alloy. Rods aren't forged either but they are dimensionally pretty stout, and the crank might as well be bomb proof lol

That pretty much eliminates piston slap unless they built them at the factory with bad clearances. Piston slap almost universally comes from thermal expansion and contraction of the pistons inside the less expanding/contracting bores.

 

[ice445]

That pretty much eliminates piston slap unless they built them at the factory with bad clearances. Piston slap almost universally comes from thermal expansion and contraction of the pistons inside the less expanding/contracting bores.

I definitely agree. I remember someone on here argued that the plasma coat cylinder liners are the problem and are somehow expanding too slow in relation to the piston, or simply not enough, creating excessive tolerance while warmed up. However, I find that hard to believe. Simply because while the PWTA liners may be a fancy way to apply it, at the end of the day it's still just iron. Simple iron, no different than a classic style sleeve other than in thickness and hardness. There shouldn't be any real differences in rate of thermal expansion. It's not some magic molecule.

Most cars also make the 2K rattle stone cold as well as hot, I know mine does. The GT350 also uses the same type of cylinder walls and doesn't have this problem, so....

 

[RalphK]

I had piston slap many years ago and ford replaced the engine. Believe me you will know when you have piston slap it is nothing like the 2K rattle. Intensity increases with RPM and is VERY loud when cold, warmed up not too bad.

 

[Entreaken]

I guess what the tech meant is that if it is piston slap, then it's "normal" in that it's exactly how piston slap sounds like. But it's NOT normal to have that sound in your engine. BTW, I've only got 3800 miles on my engine but I've NEVER had the "2K rattle" in my engine, though I've heard the "tick-tick" noise that's probably coming from the DI injectors when they actuate because it sounds like every other DI engine I've heard, from Honda "Earth Dream" engines (all DI) and Hyundai/Kia models as well. Of course I don't hear it all the time as they don't operate all the time (I don't know when the PCM activates the DI or port injectors under what operating conditions.) Due to the very high fuel pressures in DI systems, the injectors are very loud compared to conventional port injectors that run between 30-50 psi (old models vs. newer port models).

I agree that this shouldn't be considered "normal" that the piston is making unwanted contact with cylinder wall and I told the Service Director as much. But now Ford seems to be playing games with me when I tried to schedule a follow-up, I was directed to talk to the service director first. Hmmm, waiting for his call this afternoon.

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