Strange droining noise at speed

[mowogg]

My car has developed a strange noise whilst at speed. I first noticed it while driving back home at Easter -the noise develops at around 58 mph, and sounds like it is coming from the front of the car. It very difficult to tell exactly where it is coming from, but no other issues are noted. The engine oil pressure is good, it is not using oil etc. It does not sound like a typical bearing noise more of a droning sound.

I changed the front wheel bearing but this does not appear to have solved it.

Symptoms seem to be

Only occurs when the car is in top and in gear -it stops as soon as the clutch is depressed
When lightly loaded, it comes on about 58mph.
When loaded with 3 people/and lots of baggage it comes on around 52mph.
It only occurs above these speeds, and is there irrespective of if the engine is pulling or coasting. It stops as soon as you slow down
No vibration/wobbles etc

I did change the tracking just before Easter –this cannot be wheel noise can it?

Any ideas?

Thanks

John

[TomLS]

So it's purely speed related, and doesn't effect the handling / feel of the vehicle at all?

Just drive slower

But seriously, could it be a loose panel which reaches its harmonic resonance at that particular speed and causes it to drum very fast?

Or perhaps a slightly misshapen piece of body work which creates wind noise (like blowing over a bottle, only much lower in pitch). Different loadings could change the appearance of this type of noise due to a different angle the vehicle sits at when differently loaded.
Possibly the angle of the wing mirrors?
Any collapsed radiator fins?
Loose engine fan bolts?
Fan belt harmonic vibration?
The list is nearly endless...

The trouble with these noises is you can't get out and check where its from

[MarkyB]

As

it stops as soon as the clutch is depressed

The engine is heavily implicated.
As Tom says it may be no more than harmonic resonance of some part, you may find that you can drive through it and find a sweet spot around 65mph.
Any faster than this is a bit high for a cruising speed on a standard Minor.

You can get a front bottom pulley with a built in damper that may well help, and won't do any harm.

[TomLS]

As

it stops as soon as the clutch is depressed

The engine is heavily implicated.

Looks like I need to go back to school and learn to read again...

[bmcecosse]

Try swapping the wheels around to see if that affects anything. Could also be prop-shaft U joints - have a feel at them to see if there is any excessive play, or indeed - loose bolts!

[mowogg]

I have already tried swapping the wheels around -no change.

I have tried to seek any loose panels, but cannot find anything. I think the sound is a mechanical sound from somewhere?

[taupe]

Hi

I had a similar noise on my mg when I first got it... I eventually tracked it down to be a worn gearbox front bearing ( First motion shaft). It sounded like it was coming from the engine and I initially suspected worn thrust bearings.

The bearing wasnt pitted or grinding just generally worn in the tracks. It gradually got worse over some thousands of miles prompting me to strip down the clutch and gearbox. I replaced the bronze bush in the end of the crankshaft at the same time and problem solved. I think it was just oscillating at a certain engine loading and was not particularly related to engine speed.

Might not be the same problem as yours though as mine diddnt stop completely when the clutch was used but did reduce somewhat... as above these noises can be very difficult to track down.

Taupe