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The all mighty piston slap. 3.1's get it too?


tornado_735
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It seems like piston slap affects vehicles that live in a colder climate for half the year. I noticed the Canadian members all have piston slap, and some of the guys in the States where it gets cold.

 

 

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I have had piston slap in the monte since i got it 2 years ago. It will not go away untill the car is warmed up and driven, And when it's really pissed it has to be warmed up, driven, And after it's up to temp, A 1st gear WOT run. :willynilly:

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I remember an Alero I has with the 3.4 sounded like the top end was coming apart.

 

I think I already said that though.

 

Mine is generally gone within the first few minutes of driving.

 

What I am concerned about now is this whine I think is coming from the alternator.

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Rachel's Regal has it. I actually forgot how loud it was, since I haven't driven a GM in a while, until just the other day. Holy hell! It was gone after a few minutes.

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so piston slap comes from the factory or does it happen over time?

Generally gets worse over time; 'cause if you heard the knock before you signed the papers...you'd buy a different car.

 

That's not to say that the problem doesn't BEGIN with the assembly of the engine; just that it's "usually" not noticeable right away.

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  • 4 years later...
you wouldnt be able to see the difference between a regular piston and a collapsed one, its that little of a change but just enough so it can rock back and forth in the cylinder bore.

 

I've been experiencing what I thought was spark knock, then it sounds like upper engine valve train noise and now I see here, it may be piston slap.

 

This paragraph was added hours after this original post. I was wondering if the rattle could be Roller Lifters? This video shows that this engine has roller lifters. I remember the Boss 351 with roller lifters and the cool mechanical sound of them but I don't remember them rattling like this. Here is the video marked just where they mentioned this.

 

Whatever it is, it sounds like it's going create a lot of wear real quick. Though diesel engines make a lot noise and miraculously last for years.

 

Under various circumstances, turning with light acceleration, it sounds as though the engine is being starved of oil flow as if the pickup tube assembly is not submerged in the oil. Then it quiets right down after I straighten out. It's also noticeable during light acceleration while in 2nd or third gear where there isn't a lot of RPM.

 

It's as disturbing as finger nails scraping a chalk board to my ears.

 

It makes me want to pull the oil pan to make sure it's all OK with the pickup tube assembly.

 

Totally quiet under certain circumstances. If I turn left and lightly push on the gas it's very noticeable.

 

Maybe if I turn right, it may not be as noticeable.

 

It's difficult to accept that much noise isn't going to cause eminent engine failure sooner than later.

 

Can anyone put my mind as ease and offer suggestions of things to look for?

 

Thanks

 

PS

You're right about not being able to see (with the naked eye) the difference between a normal and collapsed piston. I remember in high school auto mechanics vocational school, being amazed at how fast the piston moves yet little wear occurs allowing this to go on for 100,000 miles or so.

 

Also, it made me acutely aware of letting the engine idle for a time before driving, especially when it's cold.

 

The piston being aluminum and the cylinder being steel have different rates of expansion. So engineers have to take this in to consideration or the piston will expand so fast it will lock up in the cylinder. So there has to be ample room for expansion until the steel cylinder has time to expand.

 

What's amazing is that much movement is even possible and is why I cringe and am wary when I hear that much rattling coming from the engine yet I'm told it's not a big deal.

Edited by wolga
typo, changed 2 to 2nd and changed quite to quiet
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My old Euro did it. It was very pronounced, but brief; usually lasting only about ~30 seconds when cold. The '92 Z34 on the other hand has a duller rattle to it that lasts upwards of ~5 minutes it seems. It could be partially lifter since it more "tick" like in sounds. Oh well.

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