Optare Solo squeaking.

[Jumpingjackflash]

Good afternoon,

I operate an Optare Solo SR with Mercedes engine. The bus is making a squeaking noise but I can not diagnose what is causing it. The symptoms are...

1. Makes a squeaking noise when driving and using throttle. Sounds like a canary is hiding in rear of bus.
2. The squeak does not get louder and faster the quicker you drive.
3. The squeak starts as soon as you set off.

However...

2. Does not make noise when lifting off throttle.
3. Does not make noise when stationary and revving engine in neutral.
4. Does not make noise when stationary and handbrake is on revving in reverse or drive.
5. Does not make noise when air is dumped and trying to build up air.

[Jumpingjackflash]

I can assure you it is not a body or trim squeak. It is a mechanical issue.