The Red October

Here's the full version....

Quite a long time ago, with maybe 20K miles on my car, I noticed it was making a rattling type noise when driving in first. The noise was RPM dependant, the frequency of the rattle would increase as speed went up. But it would only make the noise when the car was in gear, and I was giving it enough gas to maintain speed or accelerate. Coasting in gear it would not make the noise. Noise could only be heard with the windows down in an area where sound would reflect back off the walls.

I mentioned it to the dealer, they said they could not reproduce it. It did not seem to have any negative impact on the car, so I let it go.

Now at 75K miles, I think it has gotten more noticeable. I can now notice it with the radio off and the windows rolled up. Its faint, but there.

A few weeks ago, I was listening to my engine idle while in the car with the windows down, and I was hearing a rattling type sound, but not with a regular frequency. This is not a even rattle like the first one, it is more irregular. I push the clutch in, and I notice the noise went away. Clutch out, it comes back. This is parked in my garage, real easy to hear the sound off the walls. When I push the clutch in, it does take a sec or two for the rattle to dissapate.

If I rev the engine with the clutch out, I can hear the rattle increase in frequency, but it is still irregular. It is very easy to hear this rattle when I put my head down towards the wheels and the ground, but it is kind of masked from above by the engine noise.

I have a 2004 1.8tqms 6 speed. No rattle in gears 2 thru 6.

Thanks for your help with this...

MikTip

along with a clutch & flywheel change.

The gearbox has to come out to do.

While its out, the clutch will often be found worn. Along with the pressure plate &amp; a flywheel resurface. With this, the rear-main seal should be changed, as well as the gearbox input shaft seal.<ul><li><a href="https://forums.audiworld.com/a4gen2/msgs/1067300.phtml">https://forums.audiworld.com/a4gen2/msgs/1067300.phtml</a</li></ul>

diagnosticator1

Based on the specific conditions described. If the DMF siezes up, or otherwise fails, the crankshaft torsional vibrations the DMF normally absorbs, will cause the gears in the trans to rattle within the free play of the gear tooth lash that exists.

For comparison, when a throw-out bearing is going bad, it usually will only make noise when the clutch pedal is pressed, and the clutch is released, and quieter or noise free when the pedal is not pressed, with the clutch engaged, because the throw-out bearing is only "loaded", when the clutch pedal is pressed and the clutch is released, not the other way around as in your case.

In your case, the noise takes a few seconds to stop AFTER your press the clutch pedal down, that is consistant with the DMF/Clutch pressure plate releasing and the torsional vibrations from the crankshaft no longer being sent through to the trans.

The Red October

Is there anything I can do to unstick it? Will a hard launch do it?

diagnosticator1

As long as it doesn't get worse.

MikTip

Audi had problems with B5 S4 DMFW's, ya'd thinks they'd improve'm on the B6...