996 turbo slight noise in 1st / 2nd gear

[sy247]

I can hear a very slight noise when accelerating in first in and second gear at low revs. It is very quiet, you can't hear it with the radio on for example but I can detect it. It was intermittent but seems pretty consistent on a long journey I made at the weekend. I would guess its a gear box problem, perhaps a worn bearing or something. Its going into an indie on Monday for a MOT / 48k service so he is going to check it out. Anyone want to hazard a guess as to what it might be?

[sportsandclassic]

Hi,

It could possibly be the main input 4 point contact bearing, not the biggest bearing in the world. We have done plenty of them.

Obviously it could be other things but that springs to mind.

Mike

[Maersk]

Spinning wheels, probably..................................

[Moosh]

sy247, what kind of noise is it? wine, whirling, rattle...............

[sy247]

It sounds a bit like the noisy diff on my 944 but it is not on the over run like the diff, just 1st / 2nd when accelerating at low revs.

Thanks for the useful 'engine' and 'spinning wheel' comments guys, that's really heplful.

[Moosh]

Not sure what a noisy diff sounds like so cannot be of much help, sorry. I had a rattle last year that happened when I was under 2000 revs, turned out to be one of the heat shields. It had lost one of its screws (a bit like me), an easy fix.

[Maersk]

Glad you appreciated the whimsy................

Could be the first stages of an input bearing going as it will be exacerbated by the torque in 1st and second. Are you sure it is not there in the upper gears as well, but you just can't hear it due to other background noise?

Diff noise is very 'groany' in its delivery and very specific to that application, consequently if it is similar............ also depending on what the diff is doing the noise can either be loud on the overrun as the pinion is pulled into the crown wheel, or noisy on acceleration as it is pushed out of perfect mesh. Just depends on the configuration of the diff and its bearings and, of course, which one is grumbling.......