Query on new noise?

[Giles_Paul]

Hi again guys,

So after a week or so of blissful driving with actual oil pressure (see other post for details on these shenanigans!) the car has now decided to become a fighter jet.

I am getting some horrendous transmission noise through the tunnel and rear of the car. Im pretty sure its not the torque tube bearings, but not sure if its the gearbox? It whines like a banshee on acceleration and deceleration and is slightly quieter on neutral throttle. I replaced the gearbox oil and its at the correct level. It had new CV’s on both ends when I did all of the work. The gearbox mount looks tired but not awful, and this noise is definitely something worse. I can only liken it to being sat on the fuselage of a Jet Fighter. Any pointers?

Thanks in advance!

 

[Waylander]

Does it go if you depress the clutch while in motion,

 

[Giles_Paul]

Yep, silence.

 

[Waylander]

Could well be the clutch release bearing, not a fun job

 

[JC]

does the pitch of the noise rise and fall with engine or road speed

 

[Giles_Paul]

The clutch is brand new along with the release bearing, probably only done 500 miles.

The noise does vary with speed yes, from a reasonably quiet whine to a jet noise. The syncros on the gearbox are loud too. In fact it reminds me of a straight cut gearbox noise...

 

[scam75]

Did you use the correct gearbox oil? A 75/90 synth or the like? It sounds like bad bearings or gears in the gearbox. However this would have manifested over time and not been turned on like a switch, if this indeed happened. Incorrect gear oil may cause that.

Is it in all gears or just some?

Stuart

 

[Giles_Paul]

Did you use the correct gearbox oil? A 75/90 synth or the like? It sounds like bad bearings or gears in the gearbox. However this would have manifested over time and not been turned on like a switch, if this indeed happened. Incorrect gear oil may cause that.

Is it in all gears or just some?

Stuart

Yes used correct gearbox oil, and it has worsened over time but now seems to have just plateaud at a certain level. The gearbox is a 12 code which I think means it has a LSD? I did wonder if this could be the issue. I might look for a used box off the dreaded eBay and fit that whilst I investigate mine. Can replace the fuel lines at the same time too, theyve been on the shelf for a few weeks and really need doing!

 

[944Turbo]

What colour was the oil that came out? some are good at quietening down a noisy box (swepco for instance - blue). And unlikely but did you remove the boot carpet at the same time? that makes the gearbox seem noisy!

Not sure where you are located but these seem a good bunch https://www.hardyengineering.co.uk/ I used to do my paper round past them 35 years ago (they had been in business a good few years already then) and had a vw polo gearbox built by them around 8 years ago. I also remember a Titanic lister (Steve Cox) getting a quote from them that was reasonable for a 944 turbo box rebuild, but that was probably 20 years ago too! I don't think he had it done in the end and I think his car was broken in Scotland and some of it may have ended up in Cumbria with some posters here!

Tony

 

[944Turbo]

Oh and if it was a factory fitted LSD you should have code 220 on the options sticker (in the boot or on the service book)
Tony

 

[JC]

The noise does vary with speed yes, from a reasonably quiet whine to a jet noise. The syncros on the gearbox are loud too. In fact it reminds me of a straight cut gearbox noise...

Well, if the pitch changes with road speed and not engine speed, you can rule out the clutch and torque tube, is there a change when going around corners, if so, then it would point to a wheel bearing

 

[Tizzy]

Paul

Mine makes a similar noise. My local specialist says it’s the gearbox pinion bearings, apparently a very common issue with 944’s and he says some of them started doing it from as little as two years old when he worked on them in an OPC. We’ve changed the gearbox oil in mine and whilst that did quieten it a little, it’s certainly very much still there. I’m advised that theres no significant risk of failure so it’s a case of living with the noise (which isn’t constant) until I bite the bullet to get it done. Cavendish advise that it’s quite a labour intensive job, as the gearbox etc all has to be dropped out. So as I’ve spent rather a lot recently on having it resprayed and the cylinder head gasket replaced, I’m going to live with it for now.

Cheers

Chris

 

[turbo jonny]

Can i join the noise reduction party ?!
Mine makes a mild scraping / bearing noise only on the overun. It will go if the clutch is depressed.
As with the OP it had a clutch replaced just a couple years ago. Also had a gearbox rebuild at the time and recently my OPC changed the gearbox oil and came to the conclusion it ”might be " the thrust bearing. My feeling is that its within the realms of normal , but i would like to know exactly where its coming from.

 

[Tizzy]

Sounds like the same noise mine makes, only quieter!

 

[scam75]

Clarks Garage (RIP) list all the gearbox types. An LSD would be very rare on a non turbo. I believe the pinion bearing is about £400 from Porsche! I used the better of my 2 used ones in my rebuild and it's fine. I replaced all the other bearings with new.

All 944's have transmission noise to some extent but the boxes are tough and normally only oil starvation kills them which happens to a lot of boxes with the poorly designed external factory oil cooler.

Stuart