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Piston slap (not to be confused with detonation or pre-ignition) is most likely to be heard in an engine that has forged pistons or one that was set up with the wrong piston to bore clearance or flat worn out. If they have the wrong clearance they can make noise from the get-go. Which one of these fits the bill? Just sayin'
So if I’m hearing that sound just in cold start, the 2.7 uses forged pistons I think, so there’s the answer.
 

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I wouldn't even venture a guess without listening to it firsthand. No guarantees without looking at piston skirts and then measuring the pistons and bores. I'm not suggesting this but bearing knock and piston slap can also sound like one another at first. Worn rod bearings soon get a very distinctive sound and are most often noticed at a lower RPM. The second video in this thread was hard for me to hear what I wanted to hear except in one certain spot. It sounded to me like it had some top-end noise (valve-train) but from underneath I could hear a noise that I couldn't distinguish.

Years ago, I was building 400 Ford engines with 351 Cleveland parts. These were real runners they'd put down 500 usable street HP. These engines would really run with large port, big valve, closed chambered heads on them. We tried parts from several manufacturers including cams pistons etc. We had one that was running a TRW Forged Piston/Piston Ring pack.

This engine was built as well as human hands could put it together following parts manufacturers very closely. It developed a noise (later confirmed as piston slap and beyond) very early in its street life, just a couple of thousand miles. I saw serval of these go beyond 70,000 miles (that was respectable back then for a forged piston engine), including my father-in-law's F150 4X4. It had been broken in properly. Its cylinder-to-wall clearance was perfect according to TRW's specs.

This engine was disassembled it had literally broken the skirts in two cylinders but the break (upside-down triangle break) was such that the skirt was still going up and down with the piston. The cylinders were undamaged. After many discussions and mailing some parts back and forth, TRW re-designed this piston including additional skirt ribbing and a "thicker" ring pack. We ended up using custom Mahle's after this happened. I don't know if the problem was resolved. :LOL:

I'm telling a long story here but the thing is you could barely hear this noise at first and it ended up literally being broken pistons. Without revving it to a couple of thousand RPMs and backing out, most simply couldn't hear it. I couldn't hear it at a sustained RPM. It got louder but it wasn't like it was just slapping one day and broken the next, very subtle over a few weeks' time. These noises don't go away, they'll get louder. I'm sure that's more than any of you wanted to read. ;)
 

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I wouldn't even venture a guess without listening to it firsthand. No guarantees without looking at piston skirts and then measuring the pistons and bores. I'm not suggesting this but bearing knock and piston slap can also sound like one another at first. Worn rod bearings soon get a very distinctive sound and are most often noticed at a lower RPM.
I don’t hear any odd sounds while driving around. It’s just at startup. For all I know it could just be the timing chain a little dry for a few seconds till oil lubricates it.
 

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Discussion Starter · #24 ·
Piston slap (not to be confused with detonation or pre-ignition) is most likely to be heard in an engine that has forged pistons or one that was set up with the wrong piston to bore clearance or flat worn out. If they have the wrong clearance they can make noise from the get-go. Which one of these fits the bill? Just sayin'
Both of my motors have done this under these exact conditions, under no other conditions is there the typical piston slap that I am accustomed too.

.
Perfect on start up cruising, driving , beating on it ,
No knock , etc..

The only thing that sticks out logically to me is the pistons floating with no load @ over 2500rpm. Under this rpm it won't do it.
( thinking of down shifting and letting the motor slow you down , then putting just a touch of input on the peddle . This is the only condition it does it in.


It has everything to do with holding the gear with light throttle.
Most notable in 1-2 gear .
Maybe there in the others as well but can't pick it out with all the additional noise.
 

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Discussion Starter · #25 ·
I wouldn't even venture a guess without listening to it firsthand. No guarantees without looking at piston skirts and then measuring the pistons and bores. I'm not suggesting this but bearing knock and piston slap can also sound like one another at first. Worn rod bearings soon get a very distinctive sound and are most often noticed at a lower RPM. The second video in this thread was hard for me to hear what I wanted to hear except in one certain spot. It sounded to me like it had some top-end noise (valve-train) but from underneath I could hear a noise that I couldn't distinguish.

Years ago, I was building 400 Ford engines with 351 Cleveland parts. These were real runners they'd put down 500 usable street HP. These engines would really run with large port, big valve, closed chambered heads on them. We tried parts from several manufacturers including cams pistons etc. We had one that was running a TRW Forged Piston/Piston Ring pack.

This engine was built as well as human hands could put it together following parts manufacturers very closely. It developed a noise (later confirmed as piston slap and beyond) very early in its street life, just a couple of thousand miles. I saw serval of these go beyond 70,000 miles (that was respectable back then for a forged piston engine), including my father-in-law's F150 4X4. It had been broken in properly. Its cylinder-to-wall clearance was perfect according to TRW's specs.

This engine was disassembled it had literally broken the skirts in two cylinders but the break (upside-down triangle break) was such that the skirt was still going up and down with the piston. The cylinders were undamaged. After many discussions and mailing some parts back and forth, TRW re-designed this piston including additional skirt ribbing and a "thicker" ring pack. We ended up using custom Mahle's after this happened. I don't know if the problem was resolved. :LOL:

I'm telling a long story here but the thing is you could barely hear this noise at first and it ended up literally being broken pistons. Without revving it to a couple of thousand RPMs and backing out, most simply couldn't hear it. I couldn't hear it at a sustained RPM. It got louder but it wasn't like it was just slapping one day and broken the next, very subtle over a few weeks' time. These noises don't go away, they'll get louder. I'm sure that's more than any of you wanted to read. ;)

I read it .
It was valuable information.
.

this also helps to clarify to me this isn't the form of slap I am seeing here.
I am familiar with the sound of slap from to much clearance, this is only under" piston float conditions".
Something that these automatic f150s don't typically see.
By float I am referring to the exact point where it's not accel. Or decal, just holding rpm with no load.
 

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Discussion Starter · #26 · (Edited)
I wouldn't even venture a guess without listening to it firsthand. No guarantees without looking at piston skirts and then measuring the pistons and bores. I'm not suggesting this but bearing knock and piston slap can also sound like one another at first. Worn rod bearings soon get a very distinctive sound and are most often noticed at a lower RPM. The second video in this thread was hard for me to hear what I wanted to hear except in one certain spot. It sounded to me like it had some top-end noise (valve-train) but from underneath I could hear a noise that I couldn't distinguish.

Years ago, I was building 400 Ford engines with 351 Cleveland parts. These were real runners they'd put down 500 usable street HP. These engines would really run with large port, big valve, closed chambered heads on them. We tried parts from several manufacturers including cams pistons etc. We had one that was running a TRW Forged Piston/Piston Ring pack.

This engine was built as well as human hands could put it together following parts manufacturers very closely. It developed a noise (later confirmed as piston slap and beyond) very early in its street life, just a couple of thousand miles. I saw serval of these go beyond 70,000 miles (that was respectable back then for a forged piston engine), including my father-in-law's F150 4X4. It had been broken in properly. Its cylinder-to-wall clearance was perfect according to TRW's specs.

This engine was disassembled it had literally broken the skirts in two cylinders but the break (upside-down triangle break) was such that the skirt was still going up and down with the piston. The cylinders were undamaged. After many discussions and mailing some parts back and forth, TRW re-designed this piston including additional skirt ribbing and a "thicker" ring pack. We ended up using custom Mahle's after this happened. I don't know if the problem was resolved. :LOL:

I'm telling a long story here but the thing is you could barely hear this noise at first and it ended up literally being broken pistons. Without revving it to a couple of thousand RPMs and backing out, most simply couldn't hear it. I couldn't hear it at a sustained RPM. It got louder but it wasn't like it was just slapping one day and broken the next, very subtle over a few weeks' time. These noises don't go away, they'll get louder. I'm sure that's more than any of you wanted to read. ;)
I stand corrected.
This is starting to sound more like poor piston to bore clearance.
Sweet. And with only 250miles on it!!
🤦🏻‍♂️
I tried attaching a video so you could here and confirm but it says I don't have allowed extension.
 

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Upload video to YouTube and then post the "share link" in your post here.
The videos you see on this forum aren't actually hosted on the forum.
 

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Discussion Starter · #28 ·
Upload video to YouTube and then post the "share link" in your post here.
The videos you see on this forum aren't actually hosted on the forum.
Awesome input,
Thanks for the proper method to use.
 
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Discussion Starter · #29 ·
I wouldn't even venture a guess without listening to it firsthand. No guarantees without looking at piston skirts and then measuring the pistons and bores. I'm not suggesting this but bearing knock and piston slap can also sound like one another at first. Worn rod bearings soon get a very distinctive sound and are most often noticed at a lower RPM. The second video in this thread was hard for me to hear what I wanted to hear except in one certain spot. It sounded to me like it had some top-end noise (valve-train) but from underneath I could hear a noise that I couldn't distinguish.

Years ago, I was building 400 Ford engines with 351 Cleveland parts. These were real runners they'd put down 500 usable street HP. These engines would really run with large port, big valve, closed chambered heads on them. We tried parts from several manufacturers including cams pistons etc. We had one that was running a TRW Forged Piston/Piston Ring pack.

This engine was built as well as human hands could put it together following parts manufacturers very closely. It developed a noise (later confirmed as piston slap and beyond) very early in its street life, just a couple of thousand miles. I saw serval of these go beyond 70,000 miles (that was respectable back then for a forged piston engine), including my father-in-law's F150 4X4. It had been broken in properly. Its cylinder-to-wall clearance was perfect according to TRW's specs.

This engine was disassembled it had literally broken the skirts in two cylinders but the break (upside-down triangle break) was such that the skirt was still going up and down with the piston. The cylinders were undamaged. After many discussions and mailing some parts back and forth, TRW re-designed this piston including additional skirt ribbing and a "thicker" ring pack. We ended up using custom Mahle's after this happened. I don't know if the problem was resolved. :LOL:

I'm telling a long story here but the thing is you could barely hear this noise at first and it ended up literally being broken pistons. Without revving it to a couple of thousand RPMs and backing out, most simply couldn't hear it. I couldn't hear it at a sustained RPM. It got louder but it wasn't like it was just slapping one day and broken the next, very subtle over a few weeks' time. These noises don't go away, they'll get louder. I'm sure that's more than any of you wanted to read. ;)

Ok figured out how to transfer information 😆.

I had to use the echo from the building to hear it.

It is only noticeable under the certain criteria I laid out for ya folks.
I have yet to be able to recreate it while driving it like a normal automatic.
And even free revving like I did in this video,I still needed to feather the throttle
If I were to blip it, it won't do it.
 
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So if you drive it normally no noise?
Sounds like an easy fix…
 

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Discussion Starter · #32 ·
So if you drive it normally no noise?
Sounds like an easy fix…
LOL!!

Yep,
As long as it's in automatic drive I cant seem to recreate it.

Although, it kinda defeats the reasoning dumping $25k into a truck you can't drive the way you want.


This has made a lot of questions rise for me.

Why did the old motor "seem" to do the same thing?

Is this what originally grenaded my old motor?

Is this something that can be tuned around. ?

Can others recreate it in their trucks?

The list goes on,
It's an interesting issue to find a solution for .
 
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Discussion Starter · #33 ·

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Just throwing this out there. Something loose in the cats? Hope it’s not in the new engine. Bad tolerance or not perfectly rebuilt correctly, the engine usually lets you know fairly soon. Happened to me once on my 67 fastback 289. Started knocking 250 miles. Feel like it’s got to be something in common with the old engine that you swapped onto the new one.
 

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Just throwing this out there. Something loose in the cats? Hope it’s not in the new engine. Bad tolerance or not perfectly rebuilt correctly, the engine usually lets you know fairly soon. Happened to me once on my 67 fastback 289. Started knocking 250 miles. Feel like it’s got to be something in common with the old engine that you swapped onto the new one.
Torque converter?
 

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Discussion Starter · #36 ·
Torque converter?
If you haven't done so yet,
Give a listen to the video I attached and tell me your thoughts.
I put it on gear heads reply thread, but I'll stick it here as well.
Not sure if the video only pops up to him, or if it shares it with the whole thread.

As for the torque converter, it's solid, no issues that I'm aware of. I am not familiar with torque converts making the piston slap sound, but that doesn't mean much, if you have any links to a T.C vid. making that sort of sound I'd gladly compare it.

I had questioned it having something to do with the trans for a moment due to it only presenting it self in manual mode.
But after playing around learning how to recreate it.
I have my mind set on piston slap , perhaps due to crummy piston to bore clearance, or ..

As long as i don't the the Revs float it doesn't seem to happen, soooooo. Turn the snails dumpers up ta 22lbs. And dial the timing up to 20° and send er.!!??
🙃🤔


Idk, it's an interesting thing.
I'd love for it to be something else,

I have another 100miles left then I'm gonna put proper oil in it and see how much shiny we have in the old oil.
Not seeing any on the dip stick, but we'll see.
 

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Discussion Starter · #38 ·
Cracked flywheel?
I did give it a once over, but I didn't go over it with a fine tooth comb.

Your ears don't register it as piston slap?

This is an oddity .

I have to put it in a make shift echo chamber, i.e next to a wall or another car, garage etc..something for the sound to bounce off of and come back to my ears for me to even hear it, and even then it had to be @ the exact conditions mentioned.
As I fine tune my understanding of it I am realizing it comes on @ 2300-2500rpm and the clatter grows louder as the rpm goes up ( BUT, it has to be a no load condition) .
Like .15 -up to .35 .load, then as soon as a load ( in either direction is achieved it goes away).

In my mind I picture the piston rocking back and forth under the no load condition, kinda being floppy. ( this would be creating the slap )but as soon there is a load applied( and fuel and air, or the force from decel, it puts pressure on the piston, the piston then tilts putting pressure on the skirt to side wall and the slap goes away.


I have adjusted my driving style up, so that while I'm driving in manual mode I up shift quicker and keep the cruising( light right foot input ) rpm @ or under 2k. ( this and automatic driving keeps the slap away )

This experience has me questioning if it was my driving habit that stressed the old motor which weakened it leading up to the observation port being installed..


Thanks for your feedback,
It is greatly appreciated.
 

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I might hear piston slap but on an engine that new, I would think the noise would basically disappear when it got warm as clearances get tighter unless there were something broken. It's tough to diagnose when it's right in front of you but audio clips are really hard for me.
 

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