I have a 2001 blazer 4x4 , I bought it and knew it needed work . Let me start by saying what's been done new spider injectors. And engine overhaul. New crank and rod and main bearings. Oil pump, timing chain set all new lifters, rings and cam bearings. Cam looked ok. So before I decided to do the overhaul I replaced all the lifters due to what I thought was a lifter tapping when it didn't go away I pulled the engine and found the rod bearings in bad shape and decided to go through the engine. After getting it back together had probloms with a p0300 code and the truck seem to run ok so after some research found out it needed a relearn after changing certain parts. By the way forgot to mention distributor is new also. So I took it to the local guy here for the relearn and went to pick it up and he said it was knocking. Which it wasn't when I left it. Anyway that's where I am. I checked torque converter bolt and flex plate and both looked good then I replaced the harmonic balancer and still the same knock. The knock sounds just the same as before it was built. Awe and by the way I thought maybe a wrist pin but those all looked good when I pulled them apart. And the bearing we pulled out did have some wear but didn't look bad enough to cause a knock. When I start it on a cola start it's as quiet as a church mouse but starts knocking as it warms up . It will stop knocking under a lode like if you put it in gear hold the brake at give it the gas. Any ideas is welcome. I wonder if I could have a bad lifter pls help..

 

Awe by the way there is about 400 mile on the engine.

 

Oh Les!...

 

Oh come on ....somebody show me some love. Any ideas

 

So I will just go ahead and say it . The guy I took it to over revved it and spun a rod bearing. Does that sound logical to anyone... So I guess it's coming back out. ��

 

Did you use same rods on rebuild???? Stretched rod????? Thinking out loud GL

 

Ive blown to V8s sounded like that when warm no sound until id coast down road, stretched rod

 

Yea same rods and Pistons. But I bet they will get changed this time.

 

Are you saying the piston could be hitting the head due to stretch in the rod. The knocking sound sounds like it's in the bottom of the engine. Or is it possible to have stretch the bolts when torqued. Causing a failed bearing.

 

I think at this point it's safe to say the engine needs to come out and be rebuilt by a qualified machine shop, or install a remanufactured engine. The only way to know what is wrong it take it apart and look. Sorry man...