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Discussion Starter #1
My 159 diesel makes a strange cyclic drubbing sound at low to medium revs while driving. It's difficult to describe but sounds like something rotating out of balance. The frequency increases with revs but is only noticeable at low revs. It comes from the front of the car so I assume it's engine, transmission or a driven component like alternator, pump etc. The car drives fine and there is no vibration at all. Since this is the only 159 i've driven lately I don't know if it's a normal 159 sound or not.

Does anyone know what it could be and should I be worried? the car has only done 19500 and is still within warranty.


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Bignige
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I had exactly the same problem on my Ti at 19k...it was the driveshafts. Had both (yes both!) replaced under warranty. Apparently a fairly common problem on 2008 159's, I think the replacements are an uprated part.
 

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Check tyres first. The blocks can wear unevenly so that at the end of the tyre life they start to get this sound. If it is, I would expect the noise to be worse under braking. A good test is to find a steep hill and coast down while applying the brakes. Also change front to rear to see if the noise alters.

Driveshafts will vary their noise on or off power.
 

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Its driveshafts bignige7. But i have had mine replaced and they are still making the noise!!!!

I took it back and the techy said the driveshafts are out of alignment. (Well thats what he thinks)
Its booked to go back in for a wishbone also so I'll let you know what the outcome is.

I know what you mean though.....low revs.....low speed...it drones as though its a wheel bearing gone etc.
 

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I had the drive shafts done on mine too - 2008 model, 1.9. I was told it was the intermediate joint in the o/s shaft that can run dry and become noisy with a womp-womp-womp noise as you roll up to traffic lights for example. There is also a theory that this resonant sound only became a nuisance on MY2008 cars or later, which changed to hollow anti roll bar at the front for weight reduction.

It wasn't a complete cure and the noise was coming back and sold the car in the end so not sure if later drive shafts completely cure the problem.
 

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Discussion Starter #6
Hmmm, thanks guys....mines an 09, based on your comments i'm going to take it in and have it looked at. Will advise outcome. :)
 

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Yes that seems to be the noise. Chief culprit is the offside driveshaft which has an intermediate joint which goes dry and actually rusts. That might be the cure although it wasn't 100% successful on mine. The noise was drastically reduced but seemed to be creeping back a few thousand miles later. Others reported a complete cure. There is a lengthy thread on the subject.
http://www.alfaowner.com/Forum/alfa-159-brera-and-946-spider/132090-constant-rubbing-noise.html
Depending on the mileage you can also suspect the wheel bearings - some have failed prematurely.

Slightly more rare was a theory that it was a resonance from the diesel pump which is mounted near the bulkhead - that should be easy to isolate because it will be engine speed related instead of road speed related.
 

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Still would eliminate tyres first. My off-side rear was getting low but before I changed it I increased the pressure and cured it.

Your sound is the Wah Wah I had but it's difficult to hear through the sound layers in your recording. Would be better rolling down a hill with the engine off.
 

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Yes, manual. I tried going downhill with engine stopped as suggested by old engineer ...could'nt reproduce the sound. Also there is even a semblance of the sound when stationary just above tick over. Very puzzling.
 

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Mine does this (09 1.9 ti)
Western tech apparently said it's just a noise they make, now I dont know if he's maybe meaning the point someone mentioned above about MY08 and later cars with the weight reduction, but I can say it definitely is more prevalent in 1st and second gear up to 2k rpm, stops in 3rd gear and above 2k, and stops when you take foot off accelerator in all situations described above.

So I thought driveshaft, I'm gonna ask about this tomorrow again 'cause I dont want my warranty up in June then it goes bang or something, although I can say that I've done almost 8k miles in it since last June (was making the noise then) and nothing has gone wrong, so maybe it is just a thing it does?! dunno..
 

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Looks as if you need to look to the engine for the sound.
Next thing to try is a long screwdriver to the ear to act as a sound amplifier. Try it on various parts of the engine and see if you can hear the worrying sound.
 

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... but I can say it definitely is more prevalent in 1st and second gear up to 2k rpm, stops in 3rd gear and above 2k, and stops when you take foot off accelerator in all situations described above.
Mine's 2.2 JTS manual, and is making the sound in situation above. The other thing to note is that the sound will only starts to appear after the engine is warmed up.
 

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Yes, manual. I tried going downhill with engine stopped as suggested by old engineer ...could'nt reproduce the sound. Also there is even a semblance of the sound when stationary just above tick over. Very puzzling.
Maybe back to the fuel pump theory - or a resonance from the power steering pump? Can you isolate the revs that make the noise loudest?
 

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Let's try to isolate the source, the sound appear under the following conditions:-
- after warmed up
- when moving low speed ~10~20mph
- on both diesel (jtdm) and petrol (JTS) engine cars
- manual gearbox
- when accelerating (load), no sound when throttle is lifted or on free gear rolling

Hence, it is unlikely to be caused by:-
- fuel pump, unlikely both diesel and petrol generate same sound
- power steering pump, otherwise there will be sound when car not moving with engine running

I think the source is from part/parts where jtdm and jts has in common, such as gearbox, clutch, flywheel and drive shaft.

I am suggesting the dual mass flywheel because it could be due to the spring and damping mechanism of the dual mass transiting from one state to the other at lower rev accelerating. At higher speed the damping state is constant hence sound is gone.

The sound appears only after warmed up because the flywheel mechanism expanded and come in tight contact.

What do you think?
 
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