Technical Whats this noise......! (engine under load)

[BurntMarmite]

MY20 160ps 2.3

If the engine is being strained a bit, e.g. trying to use low down torque rather than revs, then there appears to be a noise which sounds somethng like a shot NSF wheel bearing, slightly metallic grindy or hollow rattily. It does sound like its emanating from the NSF location but noises travel, but would guess mid/lower side of near side of engine bay.

If the torque is decreased (e.g. revs increase) the noise goes - so it definitely isn't wheel bearing (but could be gearbox?).

Happens in any gear even 6ths on motorway going up hill.

But no other unexpected engine noises

Any suggestions?

 

[Crossingkeeper]

A random suggestion based on you mentioning that the noise is similar to a wheel bearing: near-side drive shaft/CV joints?

However if the code 'MY20' is the build year this is unlikely unless you've done a huge mileage

 

[Mike1alike]

When you here it next, press the clutch pedal. If the noise stops it means it's coming from inside of the gearbox and it probably is caused by a bearing.

 

[BurntMarmite]

Thanks for your replies

When you here it next, press the clutch pedal. If the noise stops it means it's coming from inside of the gearbox and it probably is caused by a bearing.

The noise would stop as its only when high torque is demanded, so stops as soon as throttle is decreased or revs rise - so as soon as clutch was depressed or throttle (torque) reduced the noise would go. Downing a gear (more revs, less torque) and the noise would go.

A random suggestion based on you mentioning that the noise is similar to a wheel bearing: near-side drive shaft/CV joints?

However if the code 'MY20' is the build year this is unlikely unless you've done a huge mileage

Yes, MY20 build year, I've had since new from July 2020. Its on around 6000 miles of road driving, no curb bumping/mounting and has been there pretty much since new.

Could well be gearbox bearing, or gearbox, or drive shaft. Or it could even be turbo/EGR (?) - no idea where they are located or what noises they are capable of!

 

[Mike1alike]

Yes, it could be the turbo. Google it to see how it looks like and where it is located on your car model, then listen to it, using a listening tube or wood (I assume you don't own a mechanic's stethoscope).

 

[Anthony489]

Hi BurntMarmite

That's quite a new van, is it not still under warranty ?

From your description, this noise appears when you are asking the engine to produce high torque i.e. wide "throttle" opening, and is present (at least it's more audible) at lower RPM. The maximum torque is usually controlled by the ECU and is fairly flat (constant) from typically 1500 to 2500 RPM, after which it drops. Engine torque is multiplied by the gearbox, progressively more as you go down from 6th through to 1st gear. So if the problem is on the output side of the gearbox (drive shafts, wheel bearings, engine mounts etc) it will tend to be worse in lower gears. However, as you still have the problem in 6th gear, this suggests to me that the problem is much more likely to be associated with the engine/flywheel/clutch or gearbox input shaft.

I'm a bit dubious about the turbo causing your described noise, as given the very high speed they spin at any noises will tend to be more of a high pitched whine.

Is the noise more noticeable before the engine warms up ? My 2008 engine gives a faint tappety rattle if I give it too much throttle (e.g after changing to 6th a bit too early) whilst still cold. I presume this is because of some mechanical clearances being a tiny bit wider under these conditions

 

[camionpilot]

Get it into a dealer ..!!

 

[oigle]

Excessively low revs with throttle applied will cause vibrations. Any motor driven at low revs with throttle will vibrate, suggesting you might like to change to a lower gear. You didn't indicate how low the revs were.
Ian.

 

[BurntMarmite]

Thanks for your replies, interesting reading. Hard to be precise on speed/rpm/conditions - I'll try and note next time I'm out in the van. Also hard to record noises - I'll try but the engine and road noise may over power it. Maybe its me (I'm "mechanically sensitive") - wife has never mentioned it..... (Though she once drove 20 miles came home and told me there was a noise from the front CV joint when actually it was a flat read tyre, but hey, she remembered what a CV joint was That was on a car, totally unrelated)

Hi BurntMarmite

That's quite a new van, is it not still under warranty ?

From your description, this noise appears when you are asking the engine to produce high torque i.e. wide "throttle" opening, and is present (at least it's more audible) at lower RPM. The maximum torque is usually controlled by the ECU and is fairly flat (constant) from typically 1500 to 2500 RPM, after which it drops. Engine torque is multiplied by the gearbox, progressively more as you go down from 6th through to 1st gear. So if the problem is on the output side of the gearbox (drive shafts, wheel bearings, engine mounts etc) it will tend to be worse in lower gears. However, as you still have the problem in 6th gear, this suggests to me that the problem is much more likely to be associated with the engine/flywheel/clutch or gearbox input shaft.

I'm a bit dubious about the turbo causing your described noise, as given the very high speed they spin at any noises will tend to be more of a high pitched whine.

Is the noise more noticeable before the engine warms up ? My 2008 engine gives a faint tappety rattle if I give it too much throttle (e.g after changing to 6th a bit too early) whilst still cold. I presume this is because of some mechanical clearances being a tiny bit wider under these conditions

Yes under warranty, and will mention it when it goes in for service.
Yes, 1500 upwards but its probably flat from 1500-2000, deffo increase (and note change) at 2000rpm
Noise is common if, say, going around a roundabout in 3rd then pulling away, or if doing 50mph in 5th (or 55 in 6th) and hitting an incline and putting more power in to maintain speed, it starts to make the noise if revs drop.
Noise is there when hot, so not related to being cold

Get it into a dealer ..!!

Thanks
Yes, under warrantee, and will be going to dealer shortly for its first service (early) but I don't have much faith in dealers and trying to understand what it is I'm trying to say. (I've had branded dealers where they are unwilling to allow technicians/mechanics speak to the customer, you have to speak to a non technical receptionist who passes messages back and forth, only for the the problem not to be looked at correctly as they didn't understand and having to book back in. - that was FORD)
Nissan van dealer, no complaints to be fair.
Fiat, unknown as yet (!)

Excessively low revs with throttle applied will cause vibrations. Any motor driven at low revs with throttle will vibrate, suggesting you might like to change to a lower gear. You didn't indicate how low the revs were.
Ian.

By low revs, I'm talking 1500 maybe. I know the vibrations you mean, its not that

 

[Mike1alike]

How is the engine oil level?

 

[Communicator]

I cannot claim to have personal experience of the 2.3 Multijet 160 PS, but I note that the maximum torque occurs at about 1500 rpm.
It is not good practice to operate a diesel engine at, or close to the maximum torque.
The noise could be diesel knock, which can sound metallic, and may be likened to tappet noise.
When the engine is trying to acceterate, the injected fuel will be at a maximum.

May I suggest trying a change in driving technique?

 

[BurntMarmite]

I cannot claim to have personal experience of the 2.3 Multijet 160 PS, but I note that the maximum torque occurs at about 1500 rpm.
It is not good practice to operate a diesel engine at, or close to the maximum torque.
The noise could be diesel knock, which can sound metallic, and may be likened to tappet noise.
When the engine is trying to acceterate, the injected fuel will be at a maximum.

May I suggest trying a change in driving technique?

Of course
Our previous vans really "enjoyed" lazy driving and pulling from low down, so maybe it is just characteristics of this engine and we'll need to adapt.
Noise isn't diesel knock, its more hollow than that - I'll need to try and record one day.

Oil level is shown as 2 or 3 dots on display, not checked dipstick recently.

 

[Anthony489]

Hi again.

(Also partly in answer to your other post about driving characteristics). The information I have about the 6 speed gearbox suggests a 6th gear ratio of 0.585 and a final drive ratio of 4.933. With 215/70 R15 tyres that works out at about 28 MPH per 1000 RPM. For the Ducato Maxi the final drive ratio was 5.231, which with 215/75 R16 tyres also gave 28 MPH per 1000 RPM.

So the torque plateau of 1500 RPM to 2500 RPM corresponds to 42 MPH to 70 MPH in 6th gear, a useful range for the UK. At 2000 RPM you will be doing your example speed of about 55 MPH in 6th, and it doesn't seem unreasonable to me to expect the engine to be capable of delivering full torque at those revs without any complaint.

If by chance your van has 16 inch tyres but kept a 4.933 final drive, the gearing will be about 7% taller, i.e. 30 MPH per 1000 RPM. Not vastly different.

It's difficult to get definitive data about gearing from Fiat, and they may well have tinkered with the gearing since that data was published, but I wouldn't expect it to differ greatly.

The only other thought I have is about the note change at 2000 RPM. I wonder if all is well with the operation of the two-stage turbocharger and its controls ? The Garrett website has some technical descriptions.

 

[BurntMarmite]

Hi again.

(Also partly in answer to your other post about driving characteristics). The information I have about the 6 speed gearbox suggests a 6th gear ratio of 0.585 and a final drive ratio of 4.933. With 215/70 R15 tyres that works out at about 28 MPH per 1000 RPM. For the Ducato Maxi the final drive ratio was 5.231, which with 215/75 R16 tyres also gave 28 MPH per 1000 RPM.

So the torque plateau of 1500 RPM to 2500 RPM corresponds to 42 MPH to 70 MPH in 6th gear, a useful range for the UK. At 2000 RPM you will be doing your example speed of about 55 MPH in 6th, and it doesn't seem unreasonable to me to expect the engine to be capable of delivering full torque at those revs without any complaint.

If by chance your van has 16 inch tyres but kept a 4.933 final drive, the gearing will be about 7% taller, i.e. 30 MPH per 1000 RPM. Not vastly different.

It's difficult to get definitive data about gearing from Fiat, and they may well have tinkered with the gearing since that data was published, but I wouldn't expect it to differ greatly.

The only other thought I have is about the note change at 2000 RPM. I wonder if all is well with the operation of the two-stage turbocharger and its controls ? The Garrett website has some technical descriptions.

Interesting
I think 2000rpm is 60mph in 6th..... (ish). The van is a standard light chassis (3.5t) MH2 but the special edition (Sportivo) came with 16" wheels and 160ps. I am not aware of gearbox ratio changes over standard
Two stage turbo? really didn't know that. There aren't any error codes in any of the modules suggesting boost outside of expectations. But definitely something like that - I thought EGR or opening up but could be a step up on the turbo. (I'm used to VNT turbos that are smooth throughout).

 

[BurntMarmite]

Posted some graphs/data in https://www.fiatforum.com/threads/my20-160ps-engine-characteristics.491198/

60mph is 1800rpm in 6th, so looks higher geared than some. We seldom go over 60, so 6th is a bit long. Tyres 225/75/R16. (OEM provided winter tyres)

The noise I can't record, I only get road noise. And its hard to describe. Its hard to hear too, and I can only describe maybe as "similar to wheel bearing", or "hollow metallic", not grinding, not rubbing, more gentle deep growl, and only under "load". It could be gearbox (with clutch in, no noise, but then not under load). Could be body trim, exhaust heat shield etc.

Not overly worrying, but would be nice to know if they all do that, or something even if trivial needs to be looked at.

 

[oigle]

One more thought. Perhaps the engine mount on the compression side might be at fault. Incorrect fitting, faulty mount etc. If noise only under heavy load, mount will be compressed. Maybe metal to metal somewhere there.