Whirring / Grinding noise but goes when clutch in

[1835harri]

Hi all,

I have a BMW 318i that makes a grindy / whirring noise when driving that only seems to go away when the clutch is depressed. It has done 207k Miles.
When it was at the garage last, they said it was the rear diff and to diagnose it properly, they would have to send it away to get looked at ??
Any further recommendations to that ?

[Riggie]

Does it change with vehicle speed? Does it do it with the gearbox in neutral whilst still moving? Diff noise may change whether under power or on the overrun.....

[1835harri]

It does it in all gears, it also quietens down when the accelerator is pressed

[iSore]

What year is it?

[1835harri]

iSore said:

What year is it?

2006 mate

[Riggie]

If the noise reduces when you accelerate but is louder on the over run (off the throttle) it's probably pinion bearings....... Take it to a gearbox specialist.

[1835harri]

Riggie said:

If the noise reduces when you accelerate but is louder on the over run (off the throttle) it's probably pinion bearings....... Take it to a gearbox specialist.

Thanks buddy, having had a google of pinion bearing problems, i think your possibly right. Quite expensive fix though from what i can see

[Locknut]

1835harri said:

It does it in all gears, it also quietens down when the accelerator is pressed

That could also be something like an engine mount.

[Riggie]

1835harri said:

Thanks buddy, having had a google of pinion bearing problems, i think your possibly right. Quite expensive fix though from what i can see

Depends if its just the bearing, at that mileage the pinion and crownwheel gears will be worn as well. Probaly cheaper to get a diff from a breaker if you can find one.

[iSore]

It's done well to last that mileage. The crown wheel and pinion last okay - it's the planet gears that also wear out as the case hardening goes.

There's place in Somerset called Gear Change who do rebuilds. About £600 to replace all the bearings and seals. You're pretty much wasting time with used ones are they're all shagged out.

[1835harri]

Sorry for bringing this back up, but i've decided to purchase another diff and get a garage to do a replacement.
I know the easiest way to find the correct part is to crawl under the car, but i rarely see it these days as the wife drives it around, so i've gone to the part website and id like someone to just confirm i have the right number if poss.

It is a 05/2006 E90 318i, right hand drive, manual.

Ive got part number : 33107524318, 3:23.

No idea if thats right of not.

[iSore]

The problem you will have is getting another diff that's any good. These 318i/320i diffs are just crap and a good used one will set you back £4-500 and a 207'000 mile 2006 E90 is worth what, £1200?

3.23 is the right ratio, but the 3.64 from a 320i will work fine as well. This diff was also used in the 116i, 118i and 120i.

[1835harri]

iSore said:

The problem you will have is getting another diff that's any good. These 318i/320i diffs are just crap and a good used one will set you back £4-500 and a 207'000 mile 2006 E90 is worth what, £1200?

3.23 is the right ratio, but the 3.64 from a 320i will work fine as well. This diff was also used in the 116i, 118i and 120i.

Thanks.

To be honest, i am just looking for something to make the noise go away so i can sell it now. It has its MOT next week so hopefully will fly through.

[iSore]

I'd sell it as it is. Early leggy E90's are selling to the kind of folk who aren't overly bothered about noise. 'Slight wheel bearing noise, £1495 ono' etc.