loud engine knocking
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Joined: Mar 2008
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loud engine knocking
its a 2.8l v6 when the engine is running its fine but when the gas pedal is pressed the loud knocking noise starts the lifters and valves are fine your can hear it from the air intake
Joined: Sep 2005
Posts: 27,899
Likes: 2,437
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: loud engine knocking
Do a compression test.
Don't forget: remove all spark plugs, block the throttle wide open, make sure the motor is fully cooled down, keep the battery HOT (like, keep a charger on it constantly) so that the engine spins the same speed on all cyls, spin the engine long enough on each cyl until the gauge quits going up. Maybe 6 or 7 compressions or thereabouts.
Post the numbers you get if you don't know how to interpret them. YOu should see smoething like 160ish psi in all cyls, with no more than about a 15 psi variation from highest to lowest.
I'm betting you'll find either 2 adjacent cylinders with low pressure (like, 30 psi or less), or one cyl with VERY HIGH pressure (like, 40-50 psi more than the others).
Don't forget: remove all spark plugs, block the throttle wide open, make sure the motor is fully cooled down, keep the battery HOT (like, keep a charger on it constantly) so that the engine spins the same speed on all cyls, spin the engine long enough on each cyl until the gauge quits going up. Maybe 6 or 7 compressions or thereabouts.
Post the numbers you get if you don't know how to interpret them. YOu should see smoething like 160ish psi in all cyls, with no more than about a 15 psi variation from highest to lowest.
I'm betting you'll find either 2 adjacent cylinders with low pressure (like, 30 psi or less), or one cyl with VERY HIGH pressure (like, 40-50 psi more than the others).
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Joined: Feb 2007
Posts: 805
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From: anderson ,sc
Car: 89 formula/00 z28
Engine: carbed 350/ls1
Transmission: 700r4/ a4
Axle/Gears: 3.23 posi/ 3.73 posi
Re: loud engine knocking
Do a compression test.
Don't forget: remove all spark plugs, block the throttle wide open, make sure the motor is fully cooled down, keep the battery HOT (like, keep a charger on it constantly) so that the engine spins the same speed on all cyls, spin the engine long enough on each cyl until the gauge quits going up. Maybe 6 or 7 compressions or thereabouts.
Post the numbers you get if you don't know how to interpret them. YOu should see smoething like 160ish psi in all cyls, with no more than about a 15 psi variation from highest to lowest.
I'm betting you'll find either 2 adjacent cylinders with low pressure (like, 30 psi or less), or one cyl with VERY HIGH pressure (like, 40-50 psi more than the others).
Don't forget: remove all spark plugs, block the throttle wide open, make sure the motor is fully cooled down, keep the battery HOT (like, keep a charger on it constantly) so that the engine spins the same speed on all cyls, spin the engine long enough on each cyl until the gauge quits going up. Maybe 6 or 7 compressions or thereabouts.
Post the numbers you get if you don't know how to interpret them. YOu should see smoething like 160ish psi in all cyls, with no more than about a 15 psi variation from highest to lowest.
I'm betting you'll find either 2 adjacent cylinders with low pressure (like, 30 psi or less), or one cyl with VERY HIGH pressure (like, 40-50 psi more than the others).
Member
Joined: Sep 2005
Posts: 483
Likes: 0
From: maine
Car: 1986 iroc z
Engine: vortec 383
Transmission: th350
Axle/Gears: 3.73 moser 12 bolt true trac
Re: loud engine knocking
valve seats, head gaskets, cylinder rings...
Last edited by rjt76; Mar 2, 2008 at 10:27 AM. Reason: more info
Joined: Sep 2005
Posts: 27,899
Likes: 2,437
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: loud engine knocking
2 adjacent low: blown head gasket
1 high: rolled exhaust lobe, broken exhaust rocker, etc.
1 high: rolled exhaust lobe, broken exhaust rocker, etc.
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iTrader: (2)
Joined: Feb 2007
Posts: 805
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From: anderson ,sc
Car: 89 formula/00 z28
Engine: carbed 350/ls1
Transmission: 700r4/ a4
Axle/Gears: 3.23 posi/ 3.73 posi
Re: loud engine knocking
my car has the same loud knocking noise. running better then it ever has. well till the trans went out yesterday. made a pass with a 1.77 60ft and 12.940 1/4. but it would of been better if i had not shifted it at 4000 in to 2nd gear. but i have 3.73 and about 100 lbs heavier than last yr.
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