Alright guys, I got my 96 Blazer running. New tranny, gaskets, timing chain and gears, rod and main bearings, rear main seal, belts and hoses, soft plugs. It ran great for about 50 miles, then i took it for a good highway drive, and it started making the same noise it made before, sounds like a hammer in there beating around. I really dont know what to think anymore, do you all have any ideas as to what it is? Any help greatly appreciated.

 

I'd like to add a few more details, I have good oil pressure. And this sound, started off only when i was off the throttle in first gear or sitting in park idling, then today i got on interstate and it just got terrible, knocking like a hammer at all times.

 

You might check your torque converter and flexplate bolts and see if they are loose.

 

There are only 2 possible problems, torque conv. bolts loose, Or the flywheel is cracked. the sound is best compared to a woodpecker when you hit the gas you apply a load to the flywheel causing the noise to stop, Until the plate cracks then it just gets worse and happens all the time. I think your flywheel is cracked, because you said the noise is now there with a load on it. I just changed my flywheel a few days ago for the same reason, The flywheel swap can be done in a few hours......bellhousing bolts are easy if you use the right tool, My trusty 14mm stubby gearwrench.

 

Alright thanks a lot guys, we'll have a look this evening and i'll let you all know what i find out.