Technical Name that noise

[crosstown]

The car is a 2008 Fiat Bravo 1.4 90 bhp.



I have the car since 2015 and as long as I have it, it's been making this noise. The latter part of the video where I rev it up and down is the most apparent and the cab is actually the best place to hear the noise - earphones might help.

It's pretty quiet and only present at idle once hot. It's quiet enough that me and the mechanic that inspected the car missed it. I did notice it the day I picked the car up and it's I assumed it's a bearing noise. I had the timing belt (the whole kit) changed immediately after buying the car but nothing changed. It doesn't change whether the aircon is on or off or if I press the clutch.

I've asked a couple of mechanics about it and never gotten the right answer. One former mechanic I know told me it sounds like an over tightened timing belt but I don't know. I've been waiting for the noise to 'develop' to become a little clearer but at this stage it's just driving me mad and I want it fixed.

Just to be clear, the noise is a soft lug-lug-lug-lug-lug-lug-lug type noise rather than the classic bearing chatter noise but there is a kind of whirring noise present above idle too.

 

[jackwhoo]

Remove auxillary belt run engine and listen for noise. If noise gone then you know is something driven by aux belt.
Does noise go when clutch pedal depressed.

 

[jackwhoo]

Does car have climate control?

 

[crosstown]

It just has aircon and pressing the clutch makes no difference.

Could you explain is there any trick to remove the aux belt tensioner in my car? I actually haven't removed too many belts and I really felt I was hanging off it but it wouldn't move. Thanks for the suggestion.

 

[jackwhoo]

If it is spring loaded tensioner use spanner on nut/bolt in center of roller to take tension off the belt and remove belt.

 

[aurick86]

Could be a bearing going bad, does sound like a dry bearing....anything driven by the auxiliary belt... possibly in the alternator.... does the noise change a little if more/less load is put on the electrical system?

It is strange that it comes back only at idle... could be a tappet.. but the frequency doesn't seem right for that.

Was it well maintained?(regular oil changes)

I've had an old Bravo MK1 with the 1.4 12v engine.. that had a tendency to clock the oil passages to the cam shaft..l. and would eventually make a similar noise.. at low idle.... one the rpm got higher there was enough oil being thrown around to stop the noise.

 

[crosstown]

Electric load had never made discernible difference but today I ran it without the alternator belt and there was no change in the noise whatsoever. Am I right in assuming that a faulty crank pulley would quieten down when not under load?

I remember when I picked the car up after getting the belt done last time is he made a point of showing me the water pump for no particular reason. I thought it was odd tbh. I asked my buddy who works in the parts shop he uses if he buys whole kits or mixes and matches, he told me he would normally get complete kits.

The noise was there before I got the belt done last time and when it didn't disappear after getting the belt done, I brought it back to the guy who promptly placated me (I actually forgot to mention the noise to him on the phone and didn't get to speak to him when I dropped it off - honestly, I thought the noise would just disappear as I made it clear I wanted the whole kit changed).

 

[MikeG20]

When i heard this noise first tought was water pump.
Simislar sound, that is not so loud, and you hear it also frome engine bay.

Other thought, clutch plate (loosen springs on it) it can be heard more in cabin than from engine bay


It si hard to determine like that

 

[crosstown]

I’ve just been asked by PM if I ever resolved this… and I did.

Subsequent to shooting this video, my uncle who is a FIAT whisperer replaced the timing belt once again using the same kit. This time he timed the engine from scratch. Maybe you don’t know this but the cam sprocket is not keyed to the shaft, it needs to be adjusted precisely and then fastened to the shaft.

Once the belt was replaced and engine timed correctly, the noise was gone. It must have been mis-timed historically. The belt also had not been over tightened.

 

[YeYe]

Thanks for that update. I've had the very same noise since having the belts changed. In my case, however, I doubt it's a timing fault as the engine runs very smoothly and is not short of power.