05 1.4 Noisy gearbox/final drive - Northern Jeff
My trusty petrol Berlingo has developed a road speed related noise which sounds like a noisy diff. It isn't engine speed or gear related. All works fine currently but the transmission becomes increasingly noisy towards 30 - 40 mph and then quietens. No vibration or harshness is apparent - just a build up of noise. I have drained & replaced the gearbox oil (there was plenty in there) with fully synthetic gear oil which has given it a smoother change (a cunning trick for old manual SAAB 9-3s/9-5s) but this hasn't made any difference to the noise it makes. It has only covered 19,000 miles and has been serviced regularly. Wheel bearings and CV joints are all tight (as you would expect at this mileage) and the tracking appears ok but hasn't been checked as it is still on soon to be replaced original tyres. Any suggestions welcome before it has some surgery.
05 1.4 Noisy gearbox/final drive - Northern Jeff
The other thing I thought of was to swap the front and back wheels around to see if it is just a resonant frequency and a characteristic of the car. The front tyres are 3/4 worn whereas the rear tyres have much mor tread and hence a larger circumference. It also seems to be quieter when laden. I heard that an old trick for quietening Hillman Imps was to put a bag of coal or rocks in the luggage bay to iron out droning.