Rotational/rocking noise from engine when lifting off from accelerator

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Apr 20, 2006 | 06:27 AM

deserTTcruiser

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Rotational/rocking noise from engine when lifting off from accelerator

I once complained about an identical noise <a href="https://forums.audiworld.com/tt/msgs/984996.phtml" target="_blank">here</a> (in Dec, 2003).

I never managed to properly identify the noise previously or solve it despite switching to a Forge DVR, but I wasn't overly concerned since it was intermittent and never became any worse.

However, it is suddenly happening even at standstill and when the gear is in neutral. It seems that I have to rev it to at least 2.5K to be able to hear the noise, and the noise is louder at higher engine speeds.

The dealer seems to think it is the turbo, but I don't buy that at all. Does the turbo even spin with no load? If it is the turbo, why can't I hear it under acceleration? Note that the performance of the car does not seem to be any worse.

Also, the dealer has checked the exhaust and downpipe for any movement that may be causing the noise and found nothing.

One other thing, I have also recently noticed that the car now emits a honk of sorts under strong acceleration. This is probably due to a torn diaphram or loose clamp/hose - right?
Could the two noises be related?

Thanks in advance for your help.

Apr 20, 2006 | 07:00 AM

kodeTT

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Joined: Jul 2001

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check your motor mounts...and also your pendulum mount as well.

if you still have the OEM mounts in...the rubber may be cracked there in one of the three spots, causing the noise.

i took my pendulum mount out after 15K miles and one of the bushings was torn. alot of stress there from the motor.

Apr 20, 2006 | 07:08 AM

deserTTcruiser

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Switched to Powerflex about 6 months back and it didn't effect the noise at all...

And I just had them check at the dealer and they say the mounts are fine. Any other thoughts?

Apr 20, 2006 | 08:04 AM

deserTTcruiser

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Correction...

I just took another drive and the sound I reported back in 2003 is not the same as this new sound as I am able to hear both if I listen closely.

The original sound from 2003 was more mechanical/metallic sounding whereas this new sound has more of a breathy quality.

I am still unsure of what is causing either though.