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Metallic rattling


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Hey all,

 

For the past couple days I've noticed this kind of metallic rattling that is random when driving down the road. It doesn't seem to be coming from the engine but the engine bay. Its a very high pitch metallic rattling that only last for a couple seconds then goes away. I haven't noticed any performance issues and I vaguely remember my first 720 making the same noise. Anyone know what it could possibly be? It is going from the driver side of the engine bay and it is not consistent. Sometimes it happens in second for a couple seconds and sometimes in the same gear it doesn't happen.  

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Does it happen when accelerating or stepping on the gas?

When you let off the gas and coast?

 

If random keep track of what and when this happens.

 

It won't be the valve lash as it remains constant unless either hot or cold.

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1 hour ago, datzenmike said:

Does it happen when accelerating or stepping on the gas?

When you let off the gas and coast?

 

If random keep track of what and when this happens.

 

It won't be the valve lash as it remains constant unless either hot or cold.

 

It happens sometimes when I am accelerating but then when I step on the gas a bit more it goes away after a couple seconds

It sometimes goes away when I let off the gas and sometimes it doesn't 

 

It usually happens when I am accelerating between 2,500-3,500 RPM but it doesn't happen every time. 

 

It seems to be coming from the driver side of the engine bay. It sounds like something shaking and making a rattling high pitched metallic sound. I tried to record it last night but my phone couldn't pick it up.  

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1 hour ago, bigleagueteague said:

Check for any play in your exhaust system. Sounds a lot like loose mounts/heat shield...

 

Yea, I was thinking it could be that because, my exhaust system is fucked. The tailpipe is basically hanging on by a thread and when it is warming up that is all you hear is the muffler just shaking like crazy. Once it warms up it doesn't shake as much but I know I need to get a whole new exhaust system. Just been looking at junkyards for the proper exhaust system. 

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The engine will torque over when accelerating and decelerating and the exhaust pipe with it.

Is the air filter loose or rubbing anything? the snorkel or the stove pipe from the exhaust manifold?

What about the AIS (air injection system) the metal tube from the exhaust manifold to the air filter housing?

 

Does the 720 have a heat shield on the under side of the down pipe to and maybe around the catalytic converter???? These rust away and move around and can be a major source of rattle..

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1 hour ago, datzenmike said:

The engine will torque over when accelerating and decelerating and the exhaust pipe with it.

Is the air filter loose or rubbing anything? the snorkel or the stove pipe from the exhaust manifold?

What about the AIS (air injection system) the metal tube from the exhaust manifold to the air filter housing?

 

Does the 720 have a heat shield on the under side of the down pipe to and maybe around the catalytic converter???? These rust away and move around and can be a major source of rattle..

 

I have a heat shield around the catalytic converter for sure and it is very rusted lol I'll tighten everything down and see what is happening. I know its not a big deal as I don't see a single shred of performance issue. Just trying to allevate the sound as its annoying than all hell. Almost as annoying as this damn shifter shaking like crazy  

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So many things could make that noise.

 

- loose carb or choke linkage

- cracked heat shield or loose bolt holding heat shield

- loose air cleaner housing or lid

- whatever that valve in the air cleaner is could be humming

- cracked or broken alternator adjuster bracket

- bottom portion of bellhousing cover plate not secure

- anything under light spring tension

- EGR tube loose or cracked, or even the EGR valve itself

- any VSV, PCV, EVAP solenoid or even a radiator cap can make that noise

 

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