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Seriously...Odd Piston Slap Starting.

galaxy

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So check this one out. Pretty sure I literally just started getting piston slap. I’ve got a rattle that meets all the descriptions I’ve found—starts around 2,500 rpm-ish, adding or removing throttle stops the rattle, cannot repeat in the garage listening under the hood, only driving down the road, etc, etc. uuugggg!!

But here’s two kickers that are totally messing with my head...I’ve had a dead silent engine and this decided to start at 3,6XX miles. Does that typically happen? Seems most I’ve read about started darn near new. I didn’t change driving habits, no oil change recently, nothing odd. Just smack out of the blue.

Here’s the other mental block...this just started inside a 100 miles of putting my Borla exhaust on. Now, logically I know there’s no darn way the two are related. But dang what are the odds? Sure seems weird. It’s bugged me so bad, I’ve thought about putting the stock exhaust back on to check it and see. But there’s just no way that’s related. Has to be coincidence. Sure is suspect though.

Any thoughts on these two questions; the late start and the exhaust?
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5.2 VooDoo

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Sure it’s not an exhaust leak?
 

Demonic

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Sure it’s not an exhaust leak?

Yeah if it's soon after installing the exhaust I'm wondering if it's something rattling or leaking on the exhaust.
 
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galaxy

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So I’ve scowered the exhaust system for loose items and rattling and can’t find anything. I didn’t think of a leak, but doesn’t seem logical. It doesn’t sound like a leak. Exhaust system fit great! It’s solid. Would be nice if it was repeatable in the garage. I could get under and listen. But it’s not repeatable at any rpm or throttle setting while sitting still and just reving.
 

tlisotta

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If it is knocking sound I would have the dealer look at it. That could be a precursor to engine failure according to my mechanic. I am no expert - just passing on a comment he made about hearing pistons knocks like you describe may be something to check on
 

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Socalrugger

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This sounds like how my piston slapping started, almost exact mileage...I’ve had no engine troubles whatsoever.... my slapping goes away after the engine warms up a bit

So check this one out. Pretty sure I literally just started getting piston slap. I’ve got a rattle that meets all the descriptions I’ve found—starts around 2,500 rpm-ish, adding or removing throttle stops the rattle, cannot repeat in the garage listening under the hood, only driving down the road, etc, etc. uuugggg!!

But here’s two kickers that are totally messing with my head...I’ve had a dead silent engine and this decided to start at 3,6XX miles. Does that typically happen? Seems most I’ve read about started darn near new. I didn’t change driving habits, no oil change recently, nothing odd. Just smack out of the blue.

Here’s the other mental block...this just started inside a 100 miles of putting my Borla exhaust on. Now, logically I know there’s no darn way the two are related. But dang what are the odds? Sure seems weird. It’s bugged me so bad, I’ve thought about putting the stock exhaust back on to check it and see. But there’s just no way that’s related. Has to be coincidence. Sure is suspect though.

Any thoughts on these two questions; the late start and the exhaust?
 

torque124

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Yep, mine started around 2600 miles, right after I got the car. It became as loud as it is now at around 3000 miles. I am at over 10k miles now, no problems, rattle has not gotten worse... Just cope with it.
 

montreal ponies

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Mine’s still very present, even after 4K on the odo. I just drive the car and don’t pay attention to it , well try to anyways. :)
 

Demonic

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So I’ve scowered the exhaust system for loose items and rattling and can’t find anything. I didn’t think of a leak, but doesn’t seem logical. It doesn’t sound like a leak. Exhaust system fit great! It’s solid. Would be nice if it was repeatable in the garage. I could get under and listen. But it’s not repeatable at any rpm or throttle setting while sitting still and just reving.

I do remember another guy having a rattle sound shortly after installing headers, and he had difficulty diagnosing it because it was only when the exhaust was hot, at which point the movement and expansion of the hot headers was causing just enough movement to make contact with a bolt and the engine vibration then created a rattling sound. When he'd get back under the car with the system cold though, it was no longer close enough to contact. Just something to consider on the differential diagnosis.
 

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wildcatgoal

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The aftermarket exhaust may not be leaking, but the factory parts that remain could certainly be.
 

nastang87xx

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Ever drive a C6 ZR1?

Find yourself an empty coffee can. Then find a pebble. Insert said pebble into coffee can. Shake coffee can. Boom, gachya-selph a ZR1. :lol: :thumbsup:

I'd rest easy to be honest.
 

Austinj427

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My engine has been rattling for as long as I have owned it. It goes away when warm though.

Nature of those super light forged pistons I guess.
 

Deca

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same here - just puzzles me that some have it and others don't...if it is because of the components..how come some don't have it (or are they deaf)
 

johnny1

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Had new a 16 GT350 and 17 GT350
I had a 16 I traded for a 17 and neither one of them had/have it. I had a new 2005 GTO and in the winter I always drove slow about a block when first started for the day cause it was so loud I was afraid I was going to throw a rod. But as soon as warmed up a bit, completely gone till sitting over night then same thing all over again. Drove car a long time and never had any engine problems.
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