(T) Grande Punto Grinding/Rubbing When Accelerating

Hi all,

I have a Multijet Sporting 1.9 with 6 speed (M32 gearbox i assume), 56 plate with 75k on it. For about a year now there has been a metallic grinding/rubbing noise when accelerating. It sounds like a bearing has failed and is rubbing; i say this because whatever is making the noise sounds like it is spinning. As my revs increase the speed at which this mysterious faulty part rotates also increases.

It occurs in all gears, but sounds louder in 1st 2nd and 3rd, especially when cold (i think it could simply sound louder as there is less road noise at lower speeds.) If i rev in neutral the noise is still there but less noticeable.

Stationary, when i depress clutch and engage 1st, there is a small and slight clunk as the gear is engaged (noticeable by sound and feeling through gear stick). If i return to neutral, release clutch pedal, then re-depress the clutch and select a gear again (any gear) the clunk occurs again (95% of the time, and sometimes louder and more obvious). When i depress the clutch and slowly move the gear selector into a gear, there is a small position along that travel where if i hold the gear stick in that position (almost halfway into the gear selection), the noise disappears completely and all i hear is the engine tickover.

If i accelerate at full throttle the noise disappears once the turbo kicks in, the noise is loudest and most obvious when i accelerate at a low-medium rate (half throttle for example)

I have seen many threads about M32 bearing problems etc, however i had all the gearbox bearings replaced in November 2016, as well as the clutch and flywheel replaced December 2016, and the noise did not go away after these repairs.

Sorry for long post but ive been trying to work this out for a while and this is all the info ive collected from driving with the issue. I would appreciate any input on this post, and thanks for reading, its a very very odd problem i just cannot find a solution for anywhere.

Kind Regards

Ben

Is the pitch (frequency) of the sound related to the road speed or the engine speed? More explicitly, if you change gear while maintain the same speed, does the pitch change (engine speed related) or stay the same (road speed related)? Knowing this will allow isolation to the input side of the gearbox (including bearings, clutch, engine components) or output side (including bearings, drive shafts, wheel bearings, brakes).


Robert G8RPI.

It is related to engine speed. E.g. the frequency at 2500 rpm in 1st is the same frequency as the frequency at 2500 rpm in 4th.

That to me doesn't sound transmission related. There's a possibility it could be the rear engine/gearbox mount that is either worn out, or failed completely causing metal on metal contact which is giving you the noise, and makes sense when you say there's a clunk engaging gears, and the frequency of the noise is the same in all gears.

This is what you are looking for, the rubber bushing is probably shot:
http://www.ebay.co.uk/itm/Engine-Mou...cAAOSwImRYOTMS

Thank you very much brickfoot. I remember looking at this mount a while ago but almost cast it aside in my head as i doubted that would cause such a noise.I was probably wrong to do so, I will look into this. Any idea how easy/difficult changing these mounts is? Id much rather do it myself than pay a garage (naturally).

Thanks again

2 bolts to remove, so can be done DIY. If you can, get the front end on axle stands, then you should be able to see the condition of the rubber bush on the mount. If it's crumbled, or allowing excessive movement, then replace it.

You may need a pry-bar to fit the new one, on order to move the engine and allow the bolt holes to line up.

Will get the car in the air tonight and have a look, hopefully you're right! Thanks again for your help.

I'm hoping it will be, and a cheap fix if so.

The symptoms seem to fit IMO, fingers crossed

Hi I've got a video of me moving the mount a little with my hand I'll link it in the next reply if you could take a look and advise please

Thanks

If you can move it by hand until the metal parts touch I'd say it needs replacing, even if it's not the source of the noise.

Robert G8RPI.

If there's movement back and forth too (you may need to try and rock the engine for this), then it will be shot.

Okay so my theory is that the rear mount is shot, causing the gearbox to be misaligned. So I'm guessing there will be damage to my input shaft and input shaft bearing. I raised the front end and let the car idle in 2nd gear and the noise was replicated somewhat. I took the front right side wheel off as I heard the loudest noise coming from that end. The O/S (driver's side) driveshaft bearing (between the long shaft and the shorter shaft down to the O/S hub) was making a horrendous knocking/ticking noise as it rotated. As it turned, I pushed down on the driveshaft right next to the bearing and the noise went away (it was turning at >1Hz thanks to my diff so I was able to do this safely). I videoed under the car as I started it and accelerated (with the wheels in the air) and the rear mount looked pretty loose. As well as the noise from the driveshaft I heard a quieter noise from around the join between gearbox and engine. So I'm thinking I'll need to replace:
Rear mount
Input shaft
Input shaft bearing
Long Driveshaft (again)

Anything else you think might be damaged?

Any links to these parts would be great fully received, I'm having trouble finding a long driveshaft replacement.

Ah the sweet smell of money combusting

The rear mount won't have caused misalignment of the input shaft, unless the gearbox-to-engine bolts were not tight when you had your clutch replaced.

Best go for the mount first, and see if that's made any improvement. It's the cheapest fix to start with

All that should be considered as a rigid block: engine, clutch, gearbox and intermediate semi-shaft, suspended in the "engine" (I'd prefer powertrain) mounts to keep it (when in good condition) in place while filtering the vibrations.
The flexible junction to the wheels is realized by the CV joints that allow both angular and axial movements up to a certain limit.
If it is noisy, your intermediate shaft bearing needs replacement; your gearbox should not have suffered from any misalignment unless -as Brickfoot said- it was loose...

BRs, Bernie