Knocking noise coming from gearbox under accelration

[ciciban]

Hey guys,

I've been experiencing a rather concerning issue with my 2007 1.4 manual Jazz and I'm hoping to get some insight from the community here. Whenever I accelerate hard, particularly in 1st, 2nd, and occasionally 3rd gear, I notice a knocking noise occurring between 2000 and 3000 rpm. Noise doesn't occur when driving in reverse. My mechanic suspects it might be related to the gearbox.

I'm aware of the infamous input shaft bearing noise that's common in lower gears. I've had that noise since I bought the car. But this knocking noise during hard acceleration has me a bit worried, especially considering the mileage on my car, which now stands at 170k kilometers (105k miles).

Has anyone else encountered a similar issue? If so, what was the root cause and how did you address it? Any advice or suggestions would be greatly appreciated.
Thanks!

[Lord Voltermore]

You could  check engine mounts for any sign that hard rubber has  deteriorated allowing too much engine/gearbox  movement .  Hard acceleration  increases how much the engine /gearbox tries to twist on its mounts due to torque.    But  some movement is normal and it may take an experienced mechanic to judge whether there is a problem.  Rubber bushes etc can deteriorate due to the age of the car ,not just kilometers driven. 
In some cars  excessive  engine movement may result in the gear stick moving its position  when you accelerate  or stop accelerating.Either visibly or can be felt if you hold the stick  .But this may not be present in all cases, and again a small amount  of movement may be normal and acceptable.   

This is only a suggestion. I am not a mechanic and have no prior experience of  Jazz mechanical problems. There could be other  causes such as drive shaft CV joints  etc. 
You could also  try this check, which I have pasted from the internet

"To check for a worn outer CV joint, put the car in reverse, turn the steering wheel all the way to one side, and drive backward in a circle. Repeat the process by turning the steering wheel in the other direction. If you hear a pronounced clicking or snapping noise, an outer CV joint may be worn out. "

[jthorpvoodoo]

Yes, I had the same symptoms...see the following:  https://clubjazz.org/forum/index.php?topic=16309.0

At first, just the input shaft bearing noise, then knocking noises which continually got worse over time/mileage and eventually the knocking noise was audible in 1st - 4th (but never 5th...presumably because 5th is on a different shaft and 1st - 4th are on the same shaft).  Knocking noise was present under load (acceleration and/or going up hill).  The higher the load, the louder the noise.

I ended up having a recondition gearbox fitted (along with a clutch as the mileage was 116k on the original), and this solved the issue/noises.

Best Regards,
Justin