Terrible Engine Rattle
Thread Starter
Instructor
Joined: Mar 2006
Posts: 140
Likes: 0
From: Houston TEXAS
Terrible Engine Rattle
I have a loud mettalic rattling sound coming from the engine bay. It is hard to locate the exact source of the sound, but appears to be in the front around the pullies. The exhaust note sounds normal and there are no other abnormal sounds/movements. Any ideas on what this could be? I read some past post and from what I can gather, it sounds too loud to be engine knock (I use 93 octane), could it be tensior (sp?) pulley or the idler pully, please help. The sound it not a sqeak.
It sort of sounds like a centrifigal supercharger from the videos I have heard. The whole "marbles in a jar".
Car Stats
97 A4
Engine: Stock Shortblock, TSP LS6 Heads, G5X3 @ 112, FAST 90, LS2 TB, LG Pro LT, B&B PRT Catback, Halltech Stinger, Vig 3200 Stall, Z06 3.42s,
It sort of sounds like a centrifigal supercharger from the videos I have heard. The whole "marbles in a jar".
Car Stats
97 A4
Engine: Stock Shortblock, TSP LS6 Heads, G5X3 @ 112, FAST 90, LS2 TB, LG Pro LT, B&B PRT Catback, Halltech Stinger, Vig 3200 Stall, Z06 3.42s,
Burning Brakes
Joined: Jul 2007
Posts: 881
Likes: 2
From: hill billy hell
Take your belts off and see if it goes away.
Eliminating all accessories is the first step.
Could be a bad bearing in your alternator or waterpump.
Actually sounds like what you are describing is a bad A/C clutch.
Can not hear it so I am guessing
Eliminating all accessories is the first step.
Could be a bad bearing in your alternator or waterpump.
Actually sounds like what you are describing is a bad A/C clutch.
Can not hear it so I am guessing
Cruising
Joined: May 2007
Posts: 13
Likes: 0
From: Gill MA
I just had a similar problem. Sounded like a bad idler pulley, replaced it and the arm as well- nothing. Took it to my dealer and it turned out to be the tranny lines rattling against the bottom of the car! Just pulled them away and problem solved...
Thread Starter
Instructor
Joined: Mar 2006
Posts: 140
Likes: 0
From: Houston TEXAS
Thanks for the help / ideas. The sound was kinda stong by the alternator, so that might be it. I'll see what happens when the belts are off.
Racer
Joined: Sep 2006
Posts: 280
Likes: 0
I have a loud mettalic rattling sound coming from the engine bay. It is hard to locate the exact source of the sound, but appears to be in the front around the pullies. The exhaust note sounds normal and there are no other abnormal sounds/movements. Any ideas on what this could be? I read some past post and from what I can gather, it sounds too loud to be engine knock (I use 93 octane), could it be tensior (sp?) pulley or the idler pully, please help. The sound it not a sqeak.
It sort of sounds like a centrifigal supercharger from the videos I have heard. The whole "marbles in a jar".
Car Stats
97 A4
Engine: Stock Shortblock, TSP LS6 Heads, G5X3 @ 112, FAST 90, LS2 TB, LG Pro LT, B&B PRT Catback, Halltech Stinger, Vig 3200 Stall, Z06 3.42s,
It sort of sounds like a centrifigal supercharger from the videos I have heard. The whole "marbles in a jar".
Car Stats
97 A4
Engine: Stock Shortblock, TSP LS6 Heads, G5X3 @ 112, FAST 90, LS2 TB, LG Pro LT, B&B PRT Catback, Halltech Stinger, Vig 3200 Stall, Z06 3.42s,
I had a similar noise like a deep metallic grinding sound especially at idle - it sounded really bad. Turned out to be the alternator AND water pump.
While I was in there, I swapped out the belt tensioners & put on Goodear Gatorback belts and ............ SILENCE, PURE SILENCE.
In fact, a co-worker commented how quiet the car ran !!
Thread Starter
Instructor
Joined: Mar 2006
Posts: 140
Likes: 0
From: Houston TEXAS
Thanks again guys!
Got some more info, it is def RPM related b/c when I rev the motor the frequency picks up, but then goes away? Maybe aroudn 2 - 2.5K. Is this thing safe to drive anywhere, or is it a do not touch until fixed?
Also how exactly do you loosen your belts? How long can you run the motor with the belts off and not damage anything? When putting it back on, do you need to torque it to a certain spec?
Can you tell I'm new to a lot of this stuff?
Got some more info, it is def RPM related b/c when I rev the motor the frequency picks up, but then goes away? Maybe aroudn 2 - 2.5K. Is this thing safe to drive anywhere, or is it a do not touch until fixed?
Also how exactly do you loosen your belts? How long can you run the motor with the belts off and not damage anything? When putting it back on, do you need to torque it to a certain spec?
Can you tell I'm new to a lot of this stuff?
Burning Brakes
Joined: Jul 2007
Posts: 881
Likes: 2
From: hill billy hell
Also how exactly do you loosen your belts? ?
How long can you run the motor with the belts off and not damage anything?
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Melting Slicks
Joined: Mar 1999
Posts: 3,210
Likes: 167
From: Rochester Hills Michigan
I think I have a bad AC clutch....bad rattle at idle, but when I turn on the AC or defrost, the loud sound goes away. Anyone else ever have this?
Last edited by RedC5; Dec 6, 2007 at 09:11 PM.
Safety Car
Joined: Dec 2004
Posts: 3,526
Likes: 17
From: Santa Fe TX
Is your crank pulley wobbling? Maybe its bad enough to hit. if you still hear the sound after your remove the belts, you may have the infamous seperating harmonic balancer
edit -- after reading the above post, the only way mine could be true is if the AC puts enough strain to slightly stop the wobble.
Most likely AC clutch/bearing.
edit -- after reading the above post, the only way mine could be true is if the AC puts enough strain to slightly stop the wobble.
Most likely AC clutch/bearing.
