99 strange noise - 3k+ RPM, foot off the gas

[merlin]

'99 g20t, 5 spd

Developed a strange noise where at 3k plus RPM when you let off the gas to coast, the car makes sort of a strange pulsing sound. That's really the only way I can figure to describe it. By pulsing I mean it comes and goes in a a reasonably quick frequency. Clutching in immediately ends the sound. Clutch is good and not slipping at all. All fluids are topped up and good.

Anyone have any thoughts as to what it might be?

[polg20]

is it just the sound or can you feel it thru the clutch pedal?

[merlin]

Thanks Polg20 for the response.

I do not feel it through the clutch pedal at all. It's mostly just the noise.

The noise does significantly decrease as the car gets warm and has been driven for a while. It happens in all gears but is most noticable in 2nd or 3rd at higher RPM's. If I clutch in, the noise immediately ends.

[javcrodgz]

A few things to narrow down the search is to figure out whether it's RPM related, speed related or a combination of both. Try revving it up at a stand still with and without the clutch depressed. Also try to listen for it and see if the sound is attributed to the speed of the vehicle or the number of revolutions of the motor. This will help pin point the problem.

[merlin]

Thanks! I did try revving it at a standstill, but not only in neutral without the clutch depressed. Let me try that and get back on this thread.

[merlin]

I tried revving clutched in and not. I really can't recreate the noise while the car isn't in gear with or without the clutch pedal depressed.

It's a very strange noise, can't really figure it out. It's louder when the car is cold and decreases as the car heats up. It's most noticeable at high RPM's in 3rd and 4th gear but can be heard in all gears. The other strange thing is that when going over bumps I can hear the noise as the suspension flexes. Could this be an exhaust issue (flex pipe?)

[roblop04]

throwout bearing..