Gearbox whine

Hello I have search everywhere something similar to my problem but hard to find out... I bought my car some times ago I didnt hear the sound first because of the supersprint loud exhaust but... When Im cruising at 3000 rpm or 4000 the car have a strange weird sound like is supercharged the sound come in 4 gear at 50km h and we can hear it a bit only when the car is loaded nothing on neutral... Its a 2006 2.7 cayman with 161 000 km or like 90 000 miles I think I have change the gear fluid with my mechanic the sound was reduced alot but it's always here... Some say it's a gearbox bearing or some say not it's diff bearing what is youre advice please because to open the gearbox is not that cheap I can try share video later.

It's much more likely to be come component involved with the accessory belt drive (aka serpentine belt). Simple test - take off the serpentine belt and run the engine briefly - max of 60 seconds. Noise gone? Now you know where to start looking. IF that's not the case - some amount of gear-noise is always going to be found in a transmission. If it is a gearbox bearing - chances are - that's not the only worn part in the gearbox/differential.

I dont hear any sound coming of gearbox if I dont drive it so that why I didnt do the serpentine belt test. The sound is like my car is supercharged at certain amount of rpm higher rpm are more quite is, at 4 k rpm we can hear the noise but above 5 k the noise is likely gone... I think the sound come when the car is heavy loaded.. At Porsche they said is the differential bearing but not with certitude... Need to open to see

I'd tend to agree with Porsche - without opening it up ($$$$$) diagnosing the problem is simply guessing. The reason I suggested the serpentine belt is you're referring to the noise being RPM related, not speed/gear related. The only way it would be only RPM-related would be if it was the input bearing in the transmission. Anything else will be speed related or gear related.

Ho ok then my problem is speed / gear related then i will see if anyone come in the topic and got the same problem. But i think i will open the gearbox later ... hope she can survive ... but i think this problem is on this car since long time and most of owner dont do anything...

Just curious - what brand/weight/type of oil are you using?

Gear oil right not motor?? its belgium brand well reputed for track and more

I asked a very specific question for a specific reason. When/if I get the answer to that question I'll comment on it.

For motor oil porsche specialist add me castrol helix , for gear oil it was Ardeca gear oil.

Ardeca gear oil - they make 6 synthetic gear oils, 3 semi-synthetic gear oils and 7 mineral based gear oils. 16 different gear oils. Your answer is still lacking precision. And engine oil isn't of any interest in this case. The reason I'm asking - different oils can have drastic differences in transmission noise levels.The noise you describe is more likely gear whine than bearing noise. Porsche 's statement "differential bearing" (but unsure) is worthless since there are probably about 8 different bearings in the differential alone, and another dozen or so in the actual gearbox. From personal experience - transmission whine can be changed drastically depending on the oil being used, even when the oil was specified by it's manufacturer as being suitable for use in the particular transmission. This is a case where it might be worthwhile trying oil supplied by the Porsche dealer. It MIGHT make a difference - or it might not.

Ho ok sorry then for my mistunderstanding the question and if you want to know the gear oil is the fully synthetic one 75W90 LS this one oilproducts The be more precise about the change of my gearoil , ive seen the old gear oil in the gearbox it was not good at all alot of little gold particle in.... realy realy black oil.... never changed in 14 years pretty sure.. that why my mechanic tell me to come when he change the oil... The gearbox seems fine because i dont have any problem at all for changing gear, just the second gear sometimes is bit hard to change when cold but i think its normal... no grind at all.... the stick dont move alone or downshift by itself when i full throttle or anything else. Thanks for help buddy.

No problem. The gold looking particles could be synchro ring wear on your 2nd gear. Nothing fatal for the gearbox, but eventually you may have to double-clutch to upshift into it when the gearbox is cold. Most people live with it until it starts popping out of gear on it's own. Good luck with it!

Thanks man, yes the second gear on sport car we know... haha, i will record when i drive it pretty sure you will hear the sound.

I post reply because ive uploaded a video where you can hear the sound its the thing like my car is supercharged you can only hear in low rpm with loaded gear... sometimes it makes the sound in higer rpm but depend how the gear is loaded... we dont hear so much motor sound i was very low rpm. You can hear it at 14 sec +-

I also heard it around 24 seconds after you shifted.. in that case it is likely input bearing noise, or some engine noise of some type. It seems related to RPM, not car speed.

Ho ok and do you think its alarmfull ? i think the car got this since some times. The car have been test by porsche center 8000 miles ago i have it in the car service book i wonder it was for sell... I think i will live some times with this problem and next 6 months open the gearbox i think depend if i keep the car for long or not what you think. Last question why a gearbox oil change or affect the sound if its a input bearing or anything else its on oil?

Sorry for this late reply , gearbox exploded during accident , a bearing was bad but everything broke off suring accident making it impossible to rebuild

Thanks for the followup, even if a bit (5 years?) delayed..

Yes sorry about that was realy busy these years had alot of problems , i still jave the car btw always great