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Discussion Starter · #1 ·
I have a 1970 240z with a '77 280z motor with stock fuel injection. Whenever I decelerate from about 2800 rpms, there is a high speed rattling noise from the engine compartment. It doesnt seem to affect perfomance, but it sure doesnt sound good! Is it my cam chain? Transmission? I dont know. Help save a Z.
 

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Front muffler?

Maybe your front muffler is shot. The higher the rpm's, the more exhaust flowing through it, so the more noise. Get underneath your car and punch the front muffler (wait till its cooled!) and it will rattle if shot.
 

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Re: Front muffler?

Might also want to check clearances around the fan/radiator/rotating accessories on the front. Engine mounts ok? On accel engine will torque one way on decel it twists the other way sometimes a 1/4" clearance on a rotating device becomes zip in a hurry.
 

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Re: Front muffler?

thanks for the responses. The rattle only appears at 2800rpms when decelerating from above that. It goes away when the rpms get to 2700. the noise happens in any gear under these conditions. I dont think it does it when the clutch is in. thanks again for the help!
 
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