Propshaft removal
 

Hi guys.

Still trying to chase this small noise I have on going with my xc90 2011.

'Noise from 40 to 60mph very faint whine or humm from rear BUT only there if you have light throttle only and sounds like its from rear?'

I have been in contact with a diff rebuild incase it's my bearing on it's way out.

I wanted to see if the prop shaft could cause this noise?

I was thinking to remove the prop shaft to trail this but I want to know car I run the car with no prop shaft?

Can I remove the prop shaft (REMEMBER MINE IS R DESIGN WITH BIGGER EXHAUSTS) with out dropping exhaust?

Hi There, yes a worn joint on the propshaft can cause this noise.

On the non R-Design cars with single exhaust I think you can remove the prop by disconnecting the exhaust front joint only - but after that removing the full exhaust is quite easy (the rear hangers bolt on). That said this method relies on being able to move the exhaust to one side which will be more tricky on the twin exhaust.

You can drive the car without the prop but keep in mind that the stability control systems expect to use AWD in a sticky situation and your insurance company might have a dim view of it.... so if you do so I would suggest for a short period for diagnostic purposes only.

Thank you very much for the reply.

Do you know if I had a diff bearing on it's way out would I still get this noise with no prop shaft connected?

As my noise is only with light throttle etc

Diff bearings turn when the wheels turn.

So a bad bearing making noise will still make noise when wheels turn.
It may sound a bit different when no prop shaft connected and the rear diff is not under load.

O right, does this rule out a faulty diff nose bearing then?

The only way I can describe the noise is a a faint whine hum (have to have radio off to hear) at speeds how ever if I take my foot OFF the gas pedal the noise goes away.

If I just breath on the gas pedal (touch as light as I can)noise will come back...

I dont want to send diff off if no issue with diff..

Does this sound more like a prop noise?

Am I right in saying if it was a diff bearing the noise would be there all the time as wheels are turning?

Can I just ADD to the above description.

When I state the faint hum is there when driving and when I take my foot off the gas the noise goes, when I state it comes back with light throttle I mean so light that you do not feel the car pull or any thing, so minor that it is like a signal input etc??

How is the haldex driven??

The haldex is driven by the propshaft which is permanently "live".

Noises like this are difficult to diagnose, but I would also suggest removing the prop is the first place to start as if you can do that yourself, it costs nothing.

I had a similar noise once on my 2003 D5 XC90 which was the propshaft front joint. It got especially worse when the torque converter locked around 55 mph.

I was thinking more of:

The prop shaft is driven live and so is the haldex unit but only the front end, when you apply throttle the haldex then locks to convert to awd?

Think you guys might be right to remove prop first..

Will drop exhaust and prop today guys and I will update.

Anything to look out for on the propshaft that can cause this noise?

Play in the front or rear joints. If you grab the shaft whilst still installed and there is any up/down or left/right movement or rotational lash then they’re likely to be worn. If that’s the case you need to remove the joint and count the drivesplines as there are two types.