Hi all.

 

First time posting here but I have been a long term covert viewer historical posts in this forum :P and it has helped me solve many problems

 

I have one problem which I cant identify and was looking for advice.

 

I have a 2003 MK1 Skoda Octavia Elegance 4x4 with the 1.8T petrol. Its done around 140k and runs great... or at least it used to.

 

In the last few months I have noticed a hum (High frequency vibration?) when driving.

 

It becomes very noticeable at 30mph onwards, however it gets better and worse as the speed increases. so its not a Linear increase in the pitch or frequency as I speed up.

 

Depressing the clutch and changing up or down gears while maintaining speed has no effect. 

 

Neither left or right corners have an effect. (Which I would expect if it was a baring) and there is no impact on steering.

 

Sometimes removing pressure from the engine, by lifting off on the accelerator will reduce the noise, but it comes back immediately when I depress the peddle again.

 

I can feel the vibration through the gearstick / peddles floor (particularly sitting in the passenger seat with my feet at the end of the footwell. It is less noticeable in the back seats.

 

Its definitely more of a high frequency vibration than a rattle (think mobile phone vibration)

 

My current theory is something along the lines of Gearbox / transmission / differential. Perhaps the transmission fluid needs replaced? I doubt it has ever been done.

 

Any thoughts suggestions comments welcome!

 

Thanks!

:coffee: 

 

 

Well, on the 4x4 the oil in the Haldex should be replaced every 40_000 miles.

 

Also, it's quite common for exhaust heat shield welds to fail, but I'd expect that to be throttle/rpm sensitive.

Thanks for the info!

 

Am I right in saying that the Haldex reservoir is joined to the transmission reservoir? so changing one entails filling both.

 

also yes the heat shield does have a little rattle, but mainly at low / stall speed. I had ruled it out but maybe I will try a repair there and see if it has an effect.

 

Thanks

Sorry I meant the rear diff and haldex share the same reservoir.

No, both separate and use different oils.