HELP! Knocking engine....!

Hi!

Went driving home from work yesterday and noticed a stange "knocking" sound from the engine, tried different rpms and at low rpm the noise disapears, but at higher rpm the knocking increases....but the funny thing is that the knocking only comes when the car is in drive, and when driving. With the car parked and giving throttle no sound, only in drive and higher speeds. Does anybody have a clue of what the problem can be? Need all the help i can get!

Thanks for all the help.

Year? Engine size? Milage? To get all the help you can on this forum, we need all the information on the vehicle you can provide.

Sorry, i forgot the most important information, its a chevy silverado 2500 4x4 1989....stock 350 tbi, th700r4. Aprox 20000 miles....

i had the same kind of knock in my 98 then got worse, i am currently rebuilding mine, it spun a main bearing. but i was told by a few service shops to check torque conveter bolts to flexplate and check the flexplate for cracks that they had seen several of the bolts coming loose and flexplates cracked. i hope for you that thats all it is and not a main bearing like mine. did you check your oil, mine looked like black metalic paint. i was surprised to find out when calling on prices for machine work that this happens quite frequently on these engines. check your flexplate and torque converter bolts. good luck.

Check and see if you have a faulty knock sensor or wiring issue. Gently tap the sensor to see if you can mimick the sound. Often the connector at these sensors get corroded. Check oil pressure with a mechanical guage for bearing wear. Check for proper base timming. Try higher octane fuel if all else fails.