Clacking sound

746 Views 14 Replies 7 Participants Last post by jtda7thfigga, 11 d ago

jtda7thfigga

Discussion Starter · 15 d ago

as of this past saturday my ss started making a clacking sound when reved or wot from dead stop, it only does it for the small period of time. car runs and drives normal, seen no difference in performance. i checked cats(weak ass cali) to make sure no baffle broke, pulled belts and started car to see if it was any pulleys, used a stethoscope on valve covers all sounds normal to me(will be pulling valve covers and inspecting). does sounds like it is coming from top end. i do have small amount of shavings in oil which from experience is somewhat normal do to wear and tear on parts. motor only has 38k miles on her. rotofab intake and two tunes from can loader. To me does not sound like rod knock but im no expert. in video around 10/11 seconds and 16/17 secs you can hear the clacking. any help or suggestions is much appricated. Thanks in advance.

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2016 chevy ss clacking sound

when reved engine clacks

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SaberOne

· #2 · 15 d ago (Edited)

My ears are pretty well shot from the military, but it doesn’t sound like it’s in the engine. Gunning the throttle and releasing abruptly, can cause a backlash/slack in accessory drive. I thrown the accessory belt in one case. There is a decoupler in the Alternator, and the idler(s) can dance around and get rackety momentarily. 🤔

jtda7thfigga

Discussion Starter · #3 · 15 d ago

SaberOne said:
My ears are pretty well shot from the military, but it doesn’t sound like it’s in the engine. Gunning the throttle and releasing abruptly, can cause a backlash/slack in accessory drive. I thrown the accessory belt in one case. There is a decoupler in the Alternator, and the idler(s) can dance around and get rackety momentarily. 🤔

So i pulled belt to check because i thought it was coming from idler pulley so only thing that was spinning was balancer and it still made that sound

. thanks for the response

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15SuperSport

· #4 · 15 d ago

Unable to watch video right now, but I can say that I have never considered metal shavings in the oil to be normal. If it was my car, I would be parking it before something that may be small turns into something big, and expensive. Hope this works out and you get to the bottom of it sooner rather than later.

Reactions: 4

SS WOT

· #5 · 15 d ago

Sounds to me like a lifter has excessive lash "aka. Loose". Rocker or lifter going out.

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jtda7thfigga

Discussion Starter · #6 · 15 d ago

15SuperSport said:
Unable to watch video right now, but I can say that I have never considered metal shavings in the oil to be normal. If it was my car, I would be parking it before something that may be small turns into something big, and expensive. Hope this works out and you get to the bottom of it sooner rather than later.

I hear ya it doesn't sound right or normal but from what I've read small amounts are ok they say it from parts wearing thus were the oil filter comes in to play. so for comparison i went to my wife cadi that has ls3 as well in it and sure enough small amount as well and she just had oil changed 2 months ago. for now its parked going into shop next tuesday when my mechanic can look at it. hopefully something simple. thanks

jtda7thfigga

Discussion Starter · #7 · 15 d ago

SS WOT said:
Sounds to me like a lifter has excessive lash "aka. Loose". Rocker or lifter going out.

thanks, ill be checking that this week

willy92

· #8 · 15 d ago (Edited)

I've found that on an aluminum block/head engine, a rod starting to knock sounds a bit like a lifter. But, a rod starting to rattle rattles most under no load, like just before a shift. But, the way that the op describes it as a noise while at the lowest oil pressure then reduces with rpm sounds like a lifter to me.

IMHO

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jtda7thfigga

Discussion Starter · #9 · 15 d ago

willy92 said:
I've found that on an aluminum block/head engine, a rod rod starting to knock sounds a bit like a lifter. But, a rod starting to rattle rattles most under no load, like just before a shift. But, the way that the op describes it as a noise while at the lowest oil pressure then reduces with rpm sounds like a lifter to me.

IMHO

thanks

wilkin4

· #10 · 15 d ago

The gunk on the dipstick is bad, something got chewed up, could be a bearing or a lifter, possibly a broken spring.....

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jtda7thfigga

Discussion Starter · #11 · 14 d ago

aight fellas got it figured out found out thanks to a friend, ol lady put good old weak cali 87 octane in her causing piston slap. drained and put in 91 with octane booster, all good

Reactions: 3

15SuperSport

· #12 · 14 d ago

jtda7thfigga said:
aight fellas got it figured out found out thanks to a friend, ol lady put good old weak cali 87 octane in her causing piston slap. drained and put in 91 with octane booster, all good

That's not piston slap you are hearing, that's detonation. Piston slap is a result of loose tolerances, short skirts and cold metals, detonation can be caused by the lower than recommended octane as in your case, among other things. Hopefully the metal in your oil is coincidental and not a result of damage from said detonation. Note that in the link below it mentions detonation at throttle tip in, much like your video. Glad you found the issue, hopefully KR wasn't affected by tuning out the knock sensors on one of your tunes.

www.motortrend.com

What Is Detonation and 8 Ways to Stop It!

If you have engine knock when accelerating, you are experiencing detonation. We explain what engine detonation is and reveal 8 ways to stop it.

www.motortrend.com

Reactions: 5

wilkin4

· #13 · 14 d ago

I believe in our cars the computer reacts very quickly, and in most cases, you won't hear any knock, the computer pulls timing very quickly to correct it.
Worst case the computer defaults to the factory low octaine tune, assuming the programming is stock, and no sensor, or electrical issues.
Change your oil and filter, and hopefully no more issues.

Reactions: 2

36thEVACVet

· #14 · 12 d ago

wilkin4 said:
I believe in our cars the computer reacts very quickly, and in most cases, you won't hear any knock, the computer pulls timing very quickly to correct it.
Worst case the computer defaults to the factory low octaine tune, assuming the programming is stock, and no sensor, or electrical issues.
Change your oil and filter, and hopefully no more issues.

From the OP: “motor only has 38k miles on her. rotofab intake and two tunes from can loader”
Those tunes must defeat the ability to run that 87 octane swill. I have run that grade in my 2016 (bone stock) with no ping-knock-detonation audible. Mostly on day long highway runs, but I have gone WOT to pass PeePaw. Engine still sounded mormal.

Reactions: 4

jtda7thfigga

Discussion Starter · #15 · 11 d ago

15SuperSport said:
That's not piston slap you are hearing, that's detonation. Piston slap is a result of loose tolerances, short skirts and cold metals, detonation can be caused by the lower than recommended octane as in your case, among other things. Hopefully the metal in your oil is coincidental and not a result of damage from said detonation. Note that in the link below it mentions detonation at throttle tip in, much like your video. Glad you found the issue, hopefully KR wasn't affected by tuning out the knock sensors on one of your tunes.

What Is Detonation and 8 Ways to Stop It!

If you have engine knock when accelerating, you are experiencing detonation. We explain what engine detonation is and reveal 8 ways to stop it.

www.motortrend.com

makes sense. thanks

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