Bad gas or low octane gas is the first thing I thought too.
Engine knocking when AC is on.
Thread Starter
Burning Brakes
Joined: Jan 2010
Posts: 863
Likes: 78
From: Walnut Creek CA
Engine knocking when AC is on.
Not sure what this could be but it started happening about 3 months ago and it just getting worst.
On a hot days and AC on, my engine makes this pronounced knocking noise every time I accelerate in 1st, 2nd and 3rd gear at 3000 rpm and higher. So when I put pressure on the engine rpm’s , engine knocks.
But when I turn AC off, knocking goes away and it runs fine. Yesterdays it was so bad that I couldn’t run AC.
Anyone else had this issue?
On a hot days and AC on, my engine makes this pronounced knocking noise every time I accelerate in 1st, 2nd and 3rd gear at 3000 rpm and higher. So when I put pressure on the engine rpm’s , engine knocks.
But when I turn AC off, knocking goes away and it runs fine. Yesterdays it was so bad that I couldn’t run AC.
Anyone else had this issue?
Retired & lovin' it!
Joined: Mar 2005
Posts: 4,475
Likes: 549
From: Jackson NJ
Not sure what this could be but it started happening about 3 months ago and it just getting worst.
On a hot days and AC on, my engine makes this pronounced knocking noise every time I accelerate in 1st, 2nd and 3rd gear at 3000 rpm and higher. So when I put pressure on the engine rpm’s , engine knocks.
But when I turn AC off, knocking goes away and it runs fine. Yesterdays it was so bad that I couldn’t run AC.
Anyone else had this issue?
On a hot days and AC on, my engine makes this pronounced knocking noise every time I accelerate in 1st, 2nd and 3rd gear at 3000 rpm and higher. So when I put pressure on the engine rpm’s , engine knocks.
But when I turn AC off, knocking goes away and it runs fine. Yesterdays it was so bad that I couldn’t run AC.
Anyone else had this issue?
Thread Starter
Burning Brakes
Joined: Jan 2010
Posts: 863
Likes: 78
From: Walnut Creek CA
Are you sure it's an engine knock? If you're only getting the noise when the AC is on, I would first suspect a loose AC pulley, the AC clutch or something in the compressor itself. Raise the hood & listen with a stethoscope or short length of hose to pinpoint where the noise is coming from.
I tried to listen with the hood up but dont hear anything, it knocks only under pressure over 3000 rpm's.
Race Director
Joined: Apr 2007
Posts: 16,025
Likes: 1,656
From: Toronto, Canada
C7 of the Year - Unmodified Finalist 2021
Not sure what this could be but it started happening about 3 months ago and it just getting worst.
On a hot days and AC on, my engine makes this pronounced knocking noise every time I accelerate in 1st, 2nd and 3rd gear at 3000 rpm and higher. So when I put pressure on the engine rpm’s , engine knocks.
But when I turn AC off, knocking goes away and it runs fine. Yesterdays it was so bad that I couldn’t run AC.
Anyone else had this issue?
On a hot days and AC on, my engine makes this pronounced knocking noise every time I accelerate in 1st, 2nd and 3rd gear at 3000 rpm and higher. So when I put pressure on the engine rpm’s , engine knocks.
But when I turn AC off, knocking goes away and it runs fine. Yesterdays it was so bad that I couldn’t run AC.
Anyone else had this issue?
Thread Starter
Burning Brakes
Joined: Jan 2010
Posts: 863
Likes: 78
From: Walnut Creek CA
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Burning Brakes
Joined: Nov 2002
Posts: 1,018
Likes: 52
From: Deltona Fl.
Just a guess but a cheap fix. Put a can of Seafoam in the tank. You may have carbon buildup.
Drifting
Joined: Jun 2011
Posts: 1,823
Likes: 2
From: Anthem AZ
I might have the same problem/sounds (2012 GS Mannual). I live in AZ so AC is almost always on. I will have to take it out on my lunch break and see if I get the same thing.
I don't hear very good but what I hear does not sound like metal on metal. It's more like someone had a small hammer and was tapping a pine board. Only when accelerating and between 2500 - 3500 RPM and the frequency changes with the RPM's.
I don't hear very good but what I hear does not sound like metal on metal. It's more like someone had a small hammer and was tapping a pine board. Only when accelerating and between 2500 - 3500 RPM and the frequency changes with the RPM's.
Team Owner
Joined: Oct 2004
Posts: 27,420
Likes: 64
From: San Clemente CA
Thread Starter
Burning Brakes
Joined: Jan 2010
Posts: 863
Likes: 78
From: Walnut Creek CA
I might have the same problem/sounds (2012 GS Mannual). I live in AZ so AC is almost always on. I will have to take it out on my lunch break and see if I get the same thing.
I don't hear very good but what I hear does not sound like metal on metal. It's more like someone had a small hammer and was tapping a pine board. Only when accelerating and between 2500 - 3500 RPM and the frequency changes with the RPM's.
I don't hear very good but what I hear does not sound like metal on metal. It's more like someone had a small hammer and was tapping a pine board. Only when accelerating and between 2500 - 3500 RPM and the frequency changes with the RPM's.
Same car as yours, 2012 GS manual
Thread Starter
Burning Brakes
Joined: Jan 2010
Posts: 863
Likes: 78
From: Walnut Creek CA
Melting Slicks
Joined: Aug 2009
Posts: 2,529
Likes: 3
From: Arlington VA
Id run some Seafoam or Techron to clean it out and see if it gets better.
Drifting
Joined: Jun 2011
Posts: 1,823
Likes: 2
From: Anthem AZ
I am sure the the chevy dealer would just tell me it normal. If it is thats fine I just wish that the dealer/anyone could tell me what it is that makes this normal noise. Please don't tell me it's the engine. That much we have figured out.
OP, how many miles on the car? Mine has 20400.
Thread Starter
Burning Brakes
Joined: Jan 2010
Posts: 863
Likes: 78
From: Walnut Creek CA
Mine also started slowly and is a little more pronounced.
I am sure the the chevy dealer would just tell me it normal. If it is thats fine I just wish that the dealer/anyone could tell me what it is that makes this normal noise. Please don't tell me it's the engine. That much we have figured out.
OP, how many miles on the car? Mine has 20400.
I am sure the the chevy dealer would just tell me it normal. If it is thats fine I just wish that the dealer/anyone could tell me what it is that makes this normal noise. Please don't tell me it's the engine. That much we have figured out.
OP, how many miles on the car? Mine has 20400.
it just seems too loud of a knocking for pinging. it even scared my girlfriend.