1989 Toyota Pickup knocking engine

i have an 89 toyota pickup with a 3.0 liter v6 engine. ive recently been hearing a knocking in my motor when my rpms get up to what im guessing is 2000-4000 rpm. i dont have a tach so im not sure but its really loud in first and second gear. not much in third, and i cant hear it in fourth or fifth. i know its not lack of oil. i change my oil every 1200-1500 miles. the motor doesnt idle rough at all. its so quiet and smooth running i have to make sure it still running when i come to a stop on several occasions. if you have any ideas they would be greatly apprieciated.

thank you for your time,


chris m.
hbg, pa




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