Replaced Flexplate and now it knocks

[79chevybigred]

Alrighty i just replaced my fleplate because the old one was so worn down the starter was having troubles grabbing. I got everything in and it is all tight and everything is on the way it came off. Now when i drove to anchorage about 45 min away going 65 if i putmore than half the accelerator down it starts to get a knocking noise from beneath me. Im sure its not in the engine and all the bolts are in the same spot as they came off. do u have any ideas what could be making the knock. it has stumped me cuz everything is tight and it is only when the accelerator pedal is halfway + depressed. im clueless.

Trey

[Big Nate's Plowing]

I had a dakota that managed to loosen the converter bolts after a trans rebuild, sounded like it was going to throw a rod through the block.... might want to check them and retorque them

[wyldman]

Loose convertor bolts. :D

[guttyy]

Chris - How similar is the sound of loose converter bolts to a rod knock ? I just replaced the oil pan gasket and found that someone broke a bolt when bolting the flex plate to the converter. About half the time it sounds like I have a rod knock - could it be the flex plate slapping the converter where the bolt is broken ? The engine is still very strong, good oil pressure, no other problems. Thanks - guttyy

[wyldman]

The sound is very similar.It will be pretty quiet at idle or cruise (you still may hear it some),and it will really rattle on acceleration.

If you have a broken bolt,I doubt the flexplate is "slapping" the convertor and making the noise.Check to make sure the other bolts are tight,and there is no sign of movement.If they are loose,and moving,you will see a shiny ring around the bolt where it is sliding on the flexplate.