Strange sound in idle (D or R)

[CMF_glomu]

Do you know what this could be?

short version:

If the gear is in N or P, the sound never comes, but if the gear is in D or R, you can hear the sound until you push gas and throttle speed increases. After an increase of 2-300 rpm, the sound goes away.

long version:

I have just bought a 97 Nissan March, automatic. It runs super except for one thing. When the engine is in idle,
quite often (regardless if the engine is hot or cold)
I hear a sound that is very similar to the high, continuous sound produced by a slipping auxiliary belt.

If the gear is in N or P, the sound NEVER comes, but if the gear is in D or R, you can hear the sound until you push the gas pedal and throttle speed increases. After an increase of 2-300 rpm, the sound goes away.

I regularly hear it when I idle in D, keeping my leg on the brake at a red light. It starts as the car stops and throttle rpm drops to base level, and it goes as i speed up.

The car was taken to a Nissan service, but after a whole day of testing, they could not tell, what the problem was.

Do you have any ideas?

Thank you for your help.

 

[CMF_glomu]

any ideas? anybody? i went through the haynes manual, but found nothing there.

 

[CMF_solarice]

any chance you can get a vid up?

Is it deffo in the engine bay? as in its not a vibration thats existing within the cabin.

The only belts youve got is alternator and water pump...and the metal belt thats inside the auto box...and the electro clutch/powder (not that, thats a belt but it does get energised when in drive as the rev rise)

But slippage from the auto box, would mean the car wont drive, and any slippage from the others would result in the opposite to how youre describing.

maybe check the water pump for side to side play, incase the bearings are on the way out...could do the same for the alternator i suppose.

Could the noise be there all the time and its just being drowned out by engine noise once your driving.?

Though i guess that wouldnt explain the lack of noise when in different gears. :/

one other option, would be the oil pump for the auto box (though im unsure if it runs all the time or if its just when in a drive gear).

The above probably hasnt helped you lol, but ive only played about with an auto micra for a few weeks while trying to find a fault, as said a vid may be useful.