Hi,

I was hoping someone could help me. Two weeks ago I had a terrible grinding noise coming from the engine bay when returning home from a drive-out in my Toyota Aygo. It is an MMT gearbox version. The grinding sounded like two metal parts clashing and grinding on each other. It was loud. Interestingly this first happened when I came to a near standstill when lifting off the accelerator (no brakes were used for this) and as the gearbox was automatically downshifting. I immediately pulled over and then continued for a little while longer (no noise at idle). The noise sadly returned when driving off again and I swiftly returned home. Luckily I was just a street away so was very very lucky otherwise I would have been in deep trouble stranded far away from home.

So was this a gearbox problem? Some issue with the selection of the gear? Or the clutch? As I completely slowed down after hearing the noise I could not tell if there was a loss of power but I think there was. I trickled my way home. Perhaps I did smell a slight whiff of burning but hard to be 100% sure. No warning lights came on the instrument dashboard and I know the Aygo has transmission (failure/excessive heat) warning lights built into the instrument dashboard.

Interestingly I have now had three drives since testing for the issue again and it has disappeared. The initial test was to see if the car would start as my TOYOTA dealership was stating I have to get the car to them myself. Later they agreed to have someone sent out to collect it. However it is worth stating that the car had an MOT at this dealership (which it passed) and the noise only came after the first drive since the MOT. So I was very upset and personally I find it a bit strange that such an issue would appear since the MOT.

Sadly (and I should not have told my dealership in hindsight) at the MOT I told them to investigate a slight burning smell from my clutch when the MMT gearbox automatically downshifts on steep hills (thus making the engine rev excessively). This was not a major issue and I lived with it for three plus years. It was only on the off-chance I told them to investigate. Someone did therefore take the car out and test for this issue and they did state they also smelt something and that it needed further investigation.

As stated no noise now since the incident and I would rather not send the car in because it will have to be stripped perhaps and who knows what other damage could potentially occur. I am not happy at the way I was treated by the TOYOTA dealership but I will have to manage this myself. I was hoping someone on the forum could potentially shed light on what engineering problem this seems to be.

Thank you.