2017 Mazda 3 wierd transmission noise

[Toilet Duck]

Afternoon all,

Hoping for a bit of help on this one. I have a 2017 Mazda 3, 2 litre petrol Skyactive, manual transmission, approx 90k miles, regularly serviced.

A noise has developed which I can only describe as a "whirring" or "whining". It is audible when driving along in gear and also when stationary in neutral and idling. If I dip the clutch, the noise stops. As I slowly release the clutch, the noise starts as I reach the biting point.

I thought it might be the clutch release bearing but googling seems to suggest the release bearing makes noises when you dip the clutch, not when you come off the clutch pedal? The noise I'm getting manifests the opposite way round. I'm hoping it's not the actual gearbox

I would be grateful for any help or advice.

Many thanks in advance

Edited by Toilet Duck on Sunday 29th January 12:23

Edited by Toilet Duck on Sunday 29th January 12:24

[GreenV8S]

You mention the noise stops when dipping the clutch, was that while stationary?

Does the noise continue if you dip the clutch while moving?

Does it stop if you dip the clutch and drop it into neutral while moving?

If it's "yes" to all the above, that suggests it's related to rotation of the layshaft and input shaft. In that case I would suspect a damaged bearing on the layshaft or input shaft.

[Toilet Duck]

GreenV8S said:

You mention the noise stops when dipping the clutch, was that while stationary?

Correct

GreenV8S said:

Does the noise continue if you dip the clutch while moving?

No, I don't think so (although I will double check this tomorrow to get a definite answer)

GreenV8S said:

Does it stop if you dip the clutch and drop it into neutral while moving?

Yes (again I will double check tomorrow, but I believe the noise stops when the clutch pedal is depressed irrespective of whether the car is moving etc)

GreenV8S said:

it's "yes" to all the above, that suggests it's related to rotation of the layshaft and input shaft. In that case I would suspect a damaged bearing on the layshaft or input shaft.

So the gearbox needs to come off and apart

Just googled layshaft and input shaft bearing. I came across this YouTube video, although a different vehicle the noise is very similar to what I'm getting.

If it is this bearing, I'm guessing it needs fixing sooner than later as I assume if the bearing completely sts itself the broken bits could cause a lot of additional damage floating around the gearbox?

Many thanks for posting

Edited by Toilet Duck on Sunday 29th January 14:34

[Toilet Duck]

Right, just took the car for a drive to double check everything.

GreenV8S said:

You mention the noise stops when dipping the clutch, was that while stationary?

Correct

GreenV8S said:

Does the noise continue if you dip the clutch while moving?

If I dip the clutch whilst moving (approx 25mph) and keep it pressed but leave the car in gear the noise is present

GreenV8S said:

Does it stop if you dip the clutch and drop it into neutral while moving?

At 25mph if I press and hold the clutch pedal and select neutral the noise stops. If I release the clutch pedal and keep in neutral the noise is absent.

Now I'm confused!

[GreenV8S]

Toilet Duck said:

At 25mph if I press and hold the clutch pedal and select neutral the noise stops. If I release the clutch pedal and keep in neutral the noise is absent.

Now I'm confused!

That last result doesn't support the theory it's a layshaft/input shaft problem, but also doesn't rule it out. Bearing noises can be affected by quite subtle factors and it's possible that the affected bearing just happens to run quietly in that particular situation.

A bearing problem does still seem the most likely cause to me. If that was mine I'd take it to a transmission specialist to see if they can confirm or deny my guess.

Alternatively, if you already know that would be beyond economic repair, you have a window of opportunity to sell it as a runner.

[Toilet Duck]

Many thanks for that.

I'm not sure how much it would cost to remove/fix the gearbox, especially as whilst it's off it would be silly not to replace the clutch etc as it's on the original. I wouldn't have a clue what to expect to pay. I know a reasonably local transmission place, I will try and get it to them later this week and see what they say.

I really wasn't looking to change cars given the crazy market prices, so would prefer to fix unless financial madness!

Again, thank you for your help

[Maxdecel]

GreenV8S said:

That last result doesn't support the theory it's a layshaft/input shaft problem, but also doesn't rule it out..

Assuming 4th is direct then noise should disappear when engaged, direct drive through mainshaft. Even if 4th or 5th are overdrive the noise should be much less as the speed differential of the mainshaft & first motion shaft is little.

[MakaveliX]

Sorry to be slightly off topic but I have the exact same car and was wondering if you ever get a grindy feel to the clutch pedal at all ? Could be related to what you experience hence my question.

Seems more prominent when the car is warm or when accelerating quickly in low gears


In regard to your question, this YouTube video may be of some assistance?
https://www.youtube.com/watch?v=cdjIF4jYQow&ab...

[Toilet Duck]

MakaveliX said:

Sorry to be slightly off topic but I have the exact same car and was wondering if you ever get a grindy feel to the clutch pedal at all ? Could be related to what you experience hence my question.

Seems more prominent when the car is warm or when accelerating quickly in low gears


In regard to your question, this YouTube video may be of some assistance?
https://www.youtube.com/watch?v=cdjIF4jYQow&ab...

No, I can't say I've ever experienced an issue with the "feel" of the clutch. The only thing close to that I've encountered is a slight squeak sometimes when releasing the pedal, but 99% sure that's coming from the pedal and inside the cabin, not in the engine bay.