Metal grating/rattling noise when accelerating only. What is it ? Video included

[DIYspanner]

Stethoscope test!

Get a thin length of stick such as garden cane, get someone to sit in and rev the engine or do so off the throttle linkage if you can manage. Touch the stick to stationary points on the engine until you pin point the noise source. When you hold the other end of the stick close to your ear, you hear the sound loud and clear.

Extreme caution!!!

 

[Rightboy91]

When you start the car up, there is a large electrical load on the battery.
Therefore, the alternator has to work hard to provide enough electricity to charge the battery up again....its under full load for a few minutes and takes a lot of energy to turn it.
At this point, if the alternator drive belt is slack it will squeal for a while as it slips over the pulleys - a faulty alternator pulley does the same, unfortunately which is a real bore! The squeal is more prevalent in the low gears as the engine is revving hard.
If your tensioner is new, then the suspicion must lie with the alternator pulley. Do the test with the drive belt off, then come back!
The good news is, nothing is going to immediately fail so nothing to panic about!
John

Hi Burnerman,thanks for that interesting information.

So I removed the drive belt today and revved up the engine yet the noise is still present. I assume this grating /rattling isn't related to the alternator or drive belt pulley s then ?

It's still squealing which is a separate issue so that's something to do with drive belt pulleys or the alternator possibly

 

[Rightboy91]

Stethoscope test!

Get a thin length of stick such as garden cane, get someone to sit in and rev the engine or do so off the throttle linkage if you can manage. Touch the stick to stationary points on the engine until you pin point the noise source. When you hold the other end of the stick close to your ear, you hear the sound loud and clear.

Extreme caution!!!

Thanks for that information. I took off the drive belt today and the noise is still there so it can't b due to those. Do you have any idea as to what it might be ?

 

[troutybrown]

Possibly Dual Mass Flywheel on the way out

 

[Rightboy91]

Possibly Dual Mass Flywheel on the way out

It sounds to be coming from the driver side area not the gearbox side area
The flywheel and clutch were replaced about 2 years and 4 months ago (almost 50,000 miles ago)

 

[troutybrown]

It sounds to be coming from the driver side area not the gearbox side area
The flywheel and clutch were replaced about 2 years and 4 months ago (almost 50,000 miles ago)

Get someone else to rev it while you listen under the bonnet.

 

[Rightboy91]

Get someone else to rev it while you listen under the bonnet.

I will try thanks. What would be your best guess atm as to what this sound might be ?

 

[DIYspanner]

Get the engine revving at a speed the noise is audible and do the stethoscope search. Should take a minute or so to identify it. From the video, it does sound like it occurs when the revs start to die off so perhaps some kind of noise caused by resonance such as a loose metal shield/cover.

 

[Burnerman]

Fine, that rules out any item that is driven by the auxiliary belt......good move.
Now we turn to the timing belt. The only thing that can really give that sort of noise are the tensioner(s) incorporated.....the water pump won't rattle, neither will the diesel pump or camshaft.
What sort of history do we have there?
Also, are there any heat shields in the exhaust pipe area that could be loose and vibrating, especially those around the catalytic converter?
John

 

[DIYspanner]

If its of any interest, regarding my suggestion on the stethoscope method of search, this!

 

[troutybrown]

If its of any interest, regarding my suggestion on the stethoscope method of search, this!

Or a long screwdriver to the ear

 

[Rightboy91]

Fine, that rules out any item that is driven by the auxiliary belt......good move.
Now we turn to the timing belt. The only thing that can really give that sort of noise are the tensioner(s) incorporated.....the water pump won't rattle, neither will the diesel pump or camshaft.
What sort of history do we have there?
Also, are there any heat shields in the exhaust pipe area that could be loose and vibrating, especially those around the catalytic converter?
John

Thank you Burnerman. I had the timing belt and water pump replaced on it at 151,800miles. The car is almost at 204,000 miles now so that's approximately 52,000 miles it has done since the timing belt and water pump were replaced.

There is a lot of stuff being said about these 1.9 CDTI fiat engines ( same engines that Alfa Romeo, Saab, Astra's and many other cars have ) that the timing belt should be replaced every 40 k due to bad water pump design shredding and taking out the belt with it. I am sure that even the repair manual states that the belt s interval is 100,000 but it's wise to replace at 40,000.


I don't think there are any heat shield on it I'll check to make sure though

Do you think this might be timing belt noise ? How can I find out without getting the belt replaced that might not be necessary yet

 

[Burnerman]

You may get somewhere by removing the timing belt top cover and running the engine - maybe the stethoscope method could get you somewhere.
Also have a listen around the rocker cover area, listening for rustle from the valve gear. At this range your video - although very good - doesn't allow us to accurately determine where the noise is coming from.
Sorry I have no knowledge of the engine being particularly hard on belts, and find it hard to believe that a water pump design could contribute to its demise!
John

 

[DIYspanner]

Just a thought!

Do the stethoscope test with a stick/long screwdriver and make a video with the phone mic close to the stick so it can pick up the noise as you close in on it.

Get someone to rev the engine while you focus on recording the noise.

 

[troutybrown]

Just a thought!

Do the stethoscope test with a stick/long screwdriver and make a video with the phone mic close to the stick so it can pick up the noise as you close in on it.

Get someone to rev the engine while you focus on recording the noise.

And depress the clutch see if the noise goes