In my Civic 1.8 Prosmatec, whenever the car shifts from gear 1 into gear 2, after a while a strange sound is heard. The sound is similar to two things grinding each other. It it is heard about 2 seconds after the gear is changed and last for a second and then disappears. It does not come at any other time but it has been heard while the car is moving even at speeds of 60-70kmh.
I have noted that if I am heavy on the throttle, the sound will not come. However, if I am light on the throttle and the car switches from gear 1 into 2 at about 2-2500k rpm, then the sound comes.
Please let me know what this sound could potentially be. I am quite worried. The car is driven 31,500km and is running solely on petrol.