So our families spare car took a crap. The trans wouldn't down shift so I did a trans flush and put a new filter in her. I go to start it up after some charging issues(wouldn't start) and now it's knocking like crazy! It def. sounds like it's comming from the front bank of the eninge. If I put my hand on the front valve cover I can litterally feel it knocking. Put your hand on the rear bank valve cover and it doens't feel nearly as bad. I'm assumming a compression test would tell me exactly what cylinder is having problems. My question to you folks is what is the main thing that would cause engine knock/engine failure on a GM 3.8ltr? I don't know to much about these pushrod engine except how to tear them apart and put them back together....haven't gotten to good at diagnosing internal engine damage. I just wanna see if it's something worth tearing the heads off over for further inspection? Please help a brotha out. Hate to have the other car break down and be stuck with out a spare car to get around in. Thanks in advance!