Noisey Engine at 30mph

Sherman

Hello

Does anybody have any ideas what is causing this?

When the engine is idle the engine noise is fine.
When the car is stationary and I rev it hard the noise increases as expected, however when I drive over a certain speed limit, approx 30mph, the engine gets very very loud.

The pressure from the exhaust seems fine when the car is idle.

Should I replace the exhaust ( or the whole car :-) )

It is a 96 Renault Megane.

Thanks

Gerry

Are you sure its the engine? Drive up to 35mph, put it into neutral and let the engine idle for a bit. See if you can still hear the noise.
If it was the engine, you would hear it before 30 ( unless you are still in first at 30 ).

Interceptor

Might just be a shagged exhaust mount causing the exhaust to bang off the underside of the car - only happens when moving because the loaded engine is pulling or pushing it on the other mounts. 96 Megane shouldn't need new exhaust IMO.

'cptr

Sherman

I have put it into neutral, I even turned off the engine on a straight piece of road, and the noise is still there.

Any ideas?

Thanks

BrianD3

Is it a loud humming noise? If it is, it could be a wheel bearing (or four)

Interceptor

Could be brakes, wheel bearings, gearbox, driveshafts or clutch. Be careful turning off the engine on the move as you lose braking when the servo is powered down, and also the steering can lock and cause you to crash (I've done it..). Describe the noise - is it a steady grumble, is it grinding, rythmic or does it sould like cheap techno?

'c

Saturnine

Sounds like a wheel bearing or something catching a driveshaft.

Sherman

Its a steady grumble. Really sounds like an exhaust but because it doesn't happen when the car is stationary, I don't think it is.

Gerry

It really sounds like a wheel bearing, ( thats the most common cause of what you are describing ). It could be the gearbox either, but that would be less likely.
Can you isolate the noise to a particular part of the car? In my limited experience, front wheel bearings go first.
You could try jacking up the car, each wheel in turn and rocking that wheel with your hands, see if one of them has much more play than the rest.
Others here will be able to give better advice.

mike65

I'll go with wheel bearing - one "test" is to listen carefully and see if the sound gets better or worse going round a bend. If going right it quietens then the right bearing is shot obviously the same test works going left. If the noise
stays the same turn your head and see you can hear it louder behind you.

Mike.

Sherman

thanks Guys,

I got the bearing replaced yesterday and I can hear the engine again!