So I have a 96 vortex 4.3l v6 and I recently rebuilt the top end of the engine. I've driven the blazer for a few months to work. It drove very nice. Then I took it on the freeway and did 60MPH for 45 miles. After that it started to rattle on the top. Well at least it sounds like the top. It stalled. Then It had a hard time starting up after that. I checked the oil and there's no metal. the oil pressure bounces at idle a bit but pretty solid. I don't know what to do and am afraid to drive or start it. Its not pulleys I've eliminated that. I need help please.

video-2011-12-03-13-16-29.3gp - YouTube

video-2011-12-03-13-22-19.3gp - YouTube

 

define top end? replaced the heads? rebuilt the heads? honestly i have no idea what it is. you can try maybe getting one of those automotive stethoscopes and see if you can pinpoint it. sounds like a rod knock or something internal but obviously without being there its really hard to tell

 

I recently pulled the heads and had a valve job down. I reassembled everything. I'm going to pull the valve covers and check everything out. Ill get a stethoscope and try that also.

 

I know that sound......... it's definetley your bottom end!!!!!! trust me, mine sounded the same right before it threw the rod out the bottom of the motor i'm afraid you wasted your time with the heads on that motor!!! Good news is u only need the short block now