Engine Whine Identification

[Yooj]

Hi,

I have a 2007 Doblo 1.9 Diesel Multijet, and this morning I noticed a distinctive whining noise coming from the engine.

Other than the noise, it is running spot on, very smooth, no smoke, no loss of fluids and no other strange noises etc.

I recorded the noise when I was driving (See here - http://www.youtube.com/watch?v=EAfJNa6rCvY&feature=youtu.be it is most noticible from around half way through the clip), and I can only describe the noise as a transmission-type whining noise, though it happens whether it is in gear or not, and the pitch of the noise increases with revs.

I took a quick look under the bonnet to see if I could get an idea where it was coming from, and it seemed to be from around the belt area, though it might of just been noise reverberating around the engine bay due to engine covers etc.

I feel that it is either aux belt or turbo, but if there is anyone with any ideas of what it could be, and possible ways of tracking down the noise, then I will be most appreciative.

Thanks

Yooj

 

[Yooj]

Weekend bump.

 

[s130]

Not the turbo. This noise an engine speed groan/whine.

Sounds like the noise is there when the engine is idling in neutral. If reving in neutral (ie no wheel / gearbox / driveshaft rotations) then the nois is definately engine and not drive chain.

Could be aux belt devices (alternator, aircon, tensioner, pulley, etc) or could be cam belt devices (fuel pump, water pump, tensioner, pully, etc)

Taking the aux belt off is easy. Simple ring spanner is all that is required to move the sprung loaded tensioner back and slip the belt off. Putting the belt back is easy except a 2nd pair of hands my be required just to help guide & hold the belt over the components at the top of the engine.

Before taking belt off note the path over the pulleys/drives on a piece of paper and also chalk a running direction arrow on the belt so when you put it back it is running in the same direction.

This is also the best way to check the condition of a poly v belt. Any wear or cracks are readily visible.

With the belt off you can hand spin all the drives & pulleys. You could even fire up the engine to see if the noise has gone.

If the noise is still present then we are almost certainly looking at something on the cambelt path. If this is the case then I would get it looked at as soon a possible!!!!!!!!

 

[alicavi]

I would say its aux belt whine or steering pump whine i had same prob with alfa made same sound found out later it was power steering low on oil sounds very like a pulley and not a turbo whine

 

[Yooj]

Thanks s130 and alicavi,

I took the aux belt off and the noise went. Giving the tensioner pulley a spin, and it appeared to have a bit of noise, so I thought this was the culprit, and so I got a new tensioner and tensioner pulley and belt and installed these.

However, the noise is still present with the new parts, so it must be one of the other parts.

There are four pulleys in total - two large and two small. I have already replaced a small one (tensioner pulley), and the other small one is the alternator pulley. One of the large ones is the crank pulley, (with the rubber damper), but I do not know what the other large one is.... can anyone shed any light what this pulley is for?

Thanks,

Yooj

 

[s130]

Itmes / services normally run off the aux drive (on a modern car) are:

alternator (driven)
hydraulic power steering pump (driven)
air conditioning compressor (driven)

crank pulley (the drive source)

belt tensioner (free rotating)
one or more other pulleys (free roating & often refered to as stretch or guide pulleys)

These additional pulleys help ensure a decent belt wrap is obtained on the crank and driven load pulleys to stop belt slippage under load.

 

[Yooj]

I have had a chance to have another look. I reckon it is the alternator or the clutch pulley on the alternator.

Will keep you all posted on any progress.

Yooj