9 replies to this topic

[Raschen]

Hello folks!
This is my first of probably many posts on this forum.
I’ve hit a problem that I can’t really get my head around.
When I started up and drove my 850 MK2 68’ after the winter there was this humming sound that came after a minute of driving (usually after hitting 30 kph/20mph), and it continues all the time after that. Initially it didn’t stop during braking. I’ve since switched all the four drums and pads (was due anyway). Now the humming stops during harder braking, and the pitch is so high during low speeds that it isn’t noticeable over 50 kph/35mph. I first thought it might be the wheel bearing, but there isn’t any play in any of the hubs, and nothing changes when I turn during driving. Can’t really locate the sound either. Both the front wheels/hubs on the axle are quite hard to spin though, and won’t spin freely in neutral. How normal is that?
Anyway, that made me think about the differential (please don’t be that). Although the engine and the drivetrain was refurbished by the previous owner not that long ago. Bought the car about a year ago, and everything went quite good throughout last year (apart from the already mentioned brakes). The engine job looks and feels really thorough. There was no sound before winter. The car has been kept in a dry and warm garage. So, does anyone have any clues? All help would be really appreciated.

[Earwax]

Probably not - but are you sure it is not wind noise 

 

I am thinking vibrating grill shutter - lifting window strips etc

[Designer]

Hi,

 

May not be the same but the Moop had a terrible high pitch drumming sound and I tracked it down to two of the rear bumper bolts being slightly loose.

Allowing the bumper to vibrate on the flange it is fixed to.

 

Paddy

[Raschen]

Probably not - but are you sure it is not wind noise

I am thinking vibrating grill shutter - lifting window strips etc

I would love if it was that, but I’m certain it’s not. A litte wind noise I can live with. It sounds very mechanical. Once the problem arises (i.e. something has warmed up a little), it won’t go away, and is more frequent and noticeable the lower the speed. For reference, it’s more like a faint sound of a kettle of tea boiling.

[Raschen]

Hi,

May not be the same but the Moop had a terrible high pitch drumming sound and I tracked it down to two of the rear bumper bolts being slightly loose.
Allowing the bumper to vibrate on the flange it is fixed to.

Paddy

Hi Paddy.
Ooh, to me it sounds more like an engine/drivetrain/wheel issue. But I’ll investigate. Thank you!

[Raschen]

Hello again.
I tried to capture the noise. I was holding around 10kph when I captured it, so the sound doesn’t vary too much. But you can hear it quite good as the constant humming in the background (the rattling is just things in the car). Sounds like a boling pot of tea.

Attached Files

•  Mini sound.mp3   720.28K   18 downloads

Edited by Raschen, 25 May 2026 - 07:42 AM.

[alpder]

Does the noise change when you add substantial electrical load (say, headlights)?

[mbolt998]

The wheels aren't usually super-easy to spin in neutral because you're stirring up the diff in order to do that. I have known the bearings to make humming noises (even without any play in them). My money's on that since you changed the drums.

[mab01uk]

The wheels aren't usually super-easy to spin in neutral because you're stirring up the diff in order to do that. I have known the bearings to make humming noises (even without any play in them). My money's on that since you changed the drums.

 

I would also agree you can sometimes have a noisy wheel bearing even with no play in them.

 

Also might be worth listening/recording the noise, while coasting in neutral on a clear road with no traffic around. 

Edited by mab01uk, 25 May 2026 - 06:27 PM.

[Earwax]

Hi Raschen - regarding how hard is it to spin the wheel - i am just now asking the same question -( after popping pot joins and redoing seals /gaskets) - and I think the wheel should continue to spin a bit after a two handed spin.

 

Dry bearings could make that noise and even though the test in gears and whilst coasting in neutral seems to discount it - I would check the clutch throw out bearing

 

-  other less likely things but i would do before deciding to delve further into the internals ( basically anything that spins fast)

 

CV inner /outer cable ends - Speedo drive  /Fan against shroud ,/ Alternator pulley bearing / check that nothing has wound its way around a spinning part ( similar to running over a hose/rope with the mower)

 

Also - check the insides of your wheels for rubbing - or more likely the CV washer has split is allowing some movement _ not sure if the drum type setup has the split version???