V6 Discussion and questions about the base carbureted or MPFI V6's and the rare SFI Turbo V6.

engine knock...

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Old Mar 14, 2011 | 05:34 PM
  #1  
evilemokid94's Avatar
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From: Elwood, IN
Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
engine knock...

Hey gues im having a werid engine noise, it sounds like a knock but it only happens at low idle, around 600 RPM or when its coming down from WOT..i cant really pinpoint it but i know its under the plenum, i think its more on the driver side..
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Old Mar 14, 2011 | 05:45 PM
  #2  
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From: Jacksonville FL
Car: 1988 camaro
Engine: cammed 3.1
Transmission: 700r4
Axle/Gears: 10 bolt 3.42
Re: engine knock...

I had an 89 rs that made knocking like noise at idle and when decelerating and the whole issue was a bad exhaust manifold gasket. It sounded like it was coming from the top end of the engine too. I have an 86 fiero gt with rod knock and it sounds like its coming from up top till you get underneath it, you can hear that here http://www.youtube.com/watch?v=0eGvzuA1yXs
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Old Mar 14, 2011 | 07:36 PM
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evilemokid94's Avatar
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From: Elwood, IN
Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
Re: engine knock...

Originally Posted by firebird904
I had an 89 rs that made knocking like noise at idle and when decelerating and the whole issue was a bad exhaust manifold gasket. It sounded like it was coming from the top end of the engine too. I have an 86 fiero gt with rod knock and it sounds like its coming from up top till you get underneath it, you can hear that here http://www.youtube.com/watch?v=0eGvzuA1yXs
are these hard to fix? also i do have a couple gaskets going out on my exaust, like my donut gaskets but from my cat back its all new, ill replace those manifold gaskets, how hard are they to replace?
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Old Mar 14, 2011 | 07:41 PM
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evilemokid94's Avatar
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From: Elwood, IN
Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
Re: engine knock...

it doesnt sound like that fierro in the video, hoping its that gasket!!
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Old Mar 14, 2011 | 09:58 PM
  #5  
evilemokid94's Avatar
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From: Elwood, IN
Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
Re: engine knock...

maybe its lose tourqe converter bolts? i know my engine moves alittle so maybe this is it?? hopefully?? HELP PLEASEEEEEE
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Old Mar 15, 2011 | 10:23 AM
  #6  
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From: Jacksonville FL
Car: 1988 camaro
Engine: cammed 3.1
Transmission: 700r4
Axle/Gears: 10 bolt 3.42
Re: engine knock...

Exhaust manifold gaskets aren't too difficult to replace it's getting them off without breaking bolt's that's the fun part. You could inspect around the manifolds to see if there's any carbon from where the exhaust gasses leak out if you don't see anything I would just leave em alone.
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Old Mar 15, 2011 | 04:29 PM
  #7  
evilemokid94's Avatar
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From: Elwood, IN
Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
Re: engine knock...

okay, anything on the loose converter bolts?
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Old Mar 15, 2011 | 05:39 PM
  #8  
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From: Florida
Car: 1989 Camaro RS
Engine: LH6
Transmission: T56
Axle/Gears: 3.42 Auburn Posi
Re: engine knock...

Originally Posted by evilemokid94
maybe its lose tourqe converter bolts? i know my engine moves alittle so maybe this is it?? hopefully?? HELP PLEASEEEEEE
Check your tranny mounts. My Dad's old 89 RS with a 305 had a bad tranny mount and the back of the motor would come up because of it.
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Old Mar 15, 2011 | 05:54 PM
  #9  
evilemokid94's Avatar
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From: Elwood, IN
Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
Re: engine knock...

guys over at camaroforum think its one of my lifters, any input?
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Old Mar 15, 2011 | 07:03 PM
  #10  
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From: LeRoy, NY
Car: 2003 Hyundai Tiburon GT
Engine: 2.7L V6
Transmission: 6-speed
Axle/Gears: 4.41
Re: engine knock...

Only way to tell is to listen to the bottom end... More than likely it is pretty serious. I had several people tell me my 2.8's noise was a lifter or "piston slap". A couple months later, the #4 connecting rod blew itself into 4 pieces and took out a good portion of the driver's side of the block. The #4 rod will almost always go first since that is usually the first to lose oil pressure when there is a problem (just like the #3 in a Chrysler 4 banger).
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Old Mar 15, 2011 | 07:21 PM
  #11  
evilemokid94's Avatar
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From: Elwood, IN
Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
Re: engine knock...

im taking it to my mechanic tomorrow so he can look at it..
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Old Mar 15, 2011 | 08:18 PM
  #12  
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From: Mesquite, Texas
Car: 89 rs, 86 Trans Am
Engine: RS-V6... Trans Am-LG4
Transmission: RS-T5... Trans Am 700r4
Re: engine knock...

Originally Posted by evilemokid94
im taking it to my mechanic tomorrow so he can look at it..

that's a good idea. I will tell you I had a grand am that had a worn motor mount, and the vibration of the engine at idle made it sound terrible. give it a little gas, things smoothed out and it was fine
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Old Mar 15, 2011 | 08:21 PM
  #13  
evilemokid94's Avatar
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From: Elwood, IN
Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
Re: engine knock...

yeah iv had several ideas, exhaust manifold gaskets,valves,lifters, loose torque converter bolts, injectors, push rods, conector rod, ect im lost..
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Old Mar 31, 2011 | 12:03 PM
  #14  
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Joined: Nov 2010
Posts: 325
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From: Sylmar, So-Cal
Car: 89 firebird bone stock for now
Engine: 2.8L V6
Transmission: 700R4
Axle/Gears: B.W 9Bolt 3.27 Posi
Re: engine knock...

thats what mine were. i had a knock also and when my uncle took apart my 2.8 he noticed that my torque converter bolts werent on properly....well 2 of them. i think he said the bolt was too long or something like that but he said when it was at low rpms it would rattle or actually wobble in this case and cause the noise. at first he said it might be the intake manifold or exhaust manifold i cant remember much but in the end it was the bolts
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