new to the site, so...hello all.

i just recently bought an '82 1500 auto 5.0 l truck. had the tranny rebuilt, and, ever since, there has been a knocking noise. not sure if they're related, but the noise happens when it's in 'd' or 'r' and under load. it is much worse when the engine is cold, then gets quieter as it heats up. only under heavy load will it knock when the engine is warm. the noise does not happen when in neutral or park, even with the engine rev'd up. the noise seems to be coming from the lower part of the engine bay, but it's hard to pinpoint exactly where.

any thoughts? thanks in advance.

 

that would be the engine make the noise

 

any thoughts on what specifically may be going on? and why it gets a little better when the engine warms up?

 

Well metal expands with heat.Sorry to say my friend, but it sounds like you have a spun bearing. Engine rebuild or replace.

 

ouch, ruffneck. thanks for your honesty. but wouldn't it also make the noise when rev'd in neutral and park, if that was the case?

 

Well the thing is it does under engine load, which means something is shifting, not good. Then again, this is only my opinion from my own experience. Could be other things like a worn wrist pin, maybe a bad harmonic balancer, etc.

 

sounds like a job for the stethoscope. thanks again, ruffneck!

 

Yes sir thats the best tool for finding a knock. Let us know what you find my friend.

 

alas, it is a bad rod bearing. anyone wanna buy an 82 gmc sierra with a rebuilt tranny (<100 miles)?