Slight rattle on acceleration through 2000 RPM

[Jazzy Hands]

Picked up my 2019 Jazz SE last week and have been getting to know it.  Generally very pleased with it, but it has an annoying, although quite quiet, rattle that occurs when you accelerate between about 1800 and 2500 RPM, or when pulling up a hill in this rev range.  Below and above this the noise cannot be heard. Only occurs when accelerating, talking the foot off the accelerator while it's making the noise immediately stops it.  It is coming from the left side of the engine bay and seems to be about where the air filter box is located. The noise is one you might expect if there was a leaf trapped somewhere in the intake ducting. However, I have removed the air box and all the ducting to inspect and it is all completely clear. Also checked all the exhaust heat shields which are quite secure and non-rattly.

I note that others have reported a similar issue (e.g. https://clubjazz.org/forum/index.php?topic=11015.msg70225#msg70225), and also with the Mk 2 (e.g. https://clubjazz.org/forum/index.php?topic=14517.msg118251#msg118251), however there are no reports on whether the origin of the noise was ever found.

What many seem to suggest is that it is pinking from the engine, but the noise is not coming from the engine, but definitely to the left of it.

Any ideas what this might be?

[Marco1979]

I had a similar rattle in my (previous) 2017 Jazz. Only under high load and low revs. Eventually the mechanic found out that one of the air conditioning tubes (between compressor and where it is connected to the air system) was a bit loose and could come into contact with another metal part causing this noise. It was fixed under warranty (car was about 1.5 years old when it occurred).

Good luck finding the source!

[Lord Voltermore]

On a similar vein to Marco it might be worth checking the cabin filter  in case it is indeed a leaf stuck in the system somewhere.

[Jazzy Hands]

Thanks for these thoughts.  I have checked around the engine bay to see if anything is loose, but will have another thorough look.  Don't think it can be the cabin air/pollen filter as it makes no difference whether the fan is on or off.

[Glosrich]

Isn't this because the engine runs Atkinson cycle up to about 2500 revs?

This is for economy, and then it switches to the normal Otto combustion cycle for higher revs.

https://clubjazz.org/forum/index.php?topic=8197.15

[olduser1]

Why not take it back ask the seller/ garage to investigate out it right. Did you notice anything on your test drive?

[Marco1979]

Isn't this because the engine runs Atkinson cycle up to about 2500 revs?

This is for economy, and then it switches to the normal Otto combustion cycle for higher revs.

https://clubjazz.org/forum/index.php?topic=8197.15

In my case, it clearly sounded as a metallic vibration. Moreover, it popped up after 1.5 years and not before. So my rattle wasn’t due to the Atkinson cycle which operated very smoothly and quietly (but not powerful).

[Glosrich]

My wife has a 2016 1.3 S manual with 49k miles full Honda service history.
If you give it some revs in first and second gear, it is noisy, but it then smoothes out higher up the revs and in higher gears.
Idle is typical quiet Honda, smooth like a sewing machine.
Doesn't use any oil between services.
I'd say it's a characteristic of this engine, as long as it's been serviced and your oil level is correct and it's not using oil, I would not be concerned.

[Jazzy Hands]

A quick update on this.  The car has been in the dealership workshop today.  They say that they think its either a clutch or gearbox issue, possibly a shaft bearing. This would be consistent with the apparent location of the noise. I am releaved that they have a diagnosis as I was convinced that they would either say 'it's normal' or 'can't find anything wrong'.  Now need to book it in to get the job done. Will be done under warranty as I only bought the car 2 weeks ago.  From what I have read the gearbox input shaft bearing is a common failure on the Mk 1, but not much around the forums about this being an issue for the Mk 3, so guess I've just been unlucky. Car has only done 48k.

[Jocko]

More likely to be the release bearing than the input shaft bearing. If a previous owner rested their foot on the clutch pedal that can cause a release bearing issue and in the worst case prematurely burn out the clutch.

[degzi]

Will be interested to see if it cures it.
Let us know how you get on.

[Jazzy Hands]

The dealership have finally done the work on my ailing Jazz.  They put a new clutch in and replaced a bearing in the gearbox. Problem solved!

[Marco1979]

Good to hear! Enjoy your rattle-free Jazz

[degzi]

Interesting. Good news indeed.