Low tone humming noise

Hi All,

After fixing my mis fire issue I decided to do a full service and a full clean, since de-greasing and jet washing the underbody I have started to hear a low tone humming noise when traveling (Heard louder when dipping clutch and coasting and I think its coming from the back).

Is this a typical bearing on its way out or could have knocked something off with a jetwash. If its a bearing anyone have a clue on how much this will set me back at a garage?

Thanks

Jacked up the backend today and checked for play in the wheels. Can't feel anything although there is a bit of a growl when I spin the wheels, thinking it's coming from the rear diff, will check the diff oil level next, judging by the rest of the car I can imagine it's never been checked or changed.

Do check the oil, won't hurt to change it either But don't be quick to condemn the diff.

The rear diff is a 4 pin type. and they are a bit notchy & whirry, swapped mine because of it, and the replacement is exactly the same.

At the time I was chasing down a rumbling from the back. Changed what felt like a whirry wheelbearing first with no improvement. Even took one of those "mechanic" people for a ride in the back, and he confirmed the noise was all from the diff, but said to leave it until it really got loud. But I swapped it out, and it was the same, so I carried on.

Some weeks later, the noise was still there but the brakes were a bit funny, first press went right down, but they pumped up and stopped alright, when I came to take the front wheels off to inspect the brakes, the nearside one was all wobbly- front wheelbearing was shot.

A new front wheelbearing later, and all the noise from the rear had gone :ohmy:

Thanks for that, I'll check the front as well. Do you know if the front are press in bearings? Saw a vid on hear about the back ones and don't have the tools do them my self.

Both front & rear are press on/in. There are some howtos on here about changing them, preferably with a press, alternatively with a hammer oven & freezer. :ohmy:

You might find a humming is tyre noise on the road surface.
Wheel bearings are more of a droning noise.

The diff tends to whine.

Thanks for the info, It's a difficult noise to explain, it's got louder now and is like a drumming noise with hum. Not sure if that makes sense.