Since I am not knowledgeable about rebuilding motors or diagnosing their problems I have decided that the best solution to solving my 96 Blazer's engine problem is a swap out. Problem is I cannot find a site where I can determine exactly what year engines I can put into my Blazer without doing a bunch of modifications. All I want to do is find the latest year motor I can unbolt and remove from one and bolt it back into mine. Get in start it up and drive. I can do the swap, I have all the tools, and I can follow instructions. If I had a garage with room to work I would attempt the rebuild of mine but no such luck. It is pull it in the driveway and replace it there also. My only other area of concern is I also want to improve the MPG if possible. Here are the specs on my Blazer in case they are needed for someone to point me in the right direction. 96 Blazer 4.3L Vortec, 4 wheel drive, auto with LE trim, all leather. It only has 146,000 original miles on it. The engine problem is there is a loud knocking on the driver side that just developed and it sounds as if there is something ticking inside the valve cover area. Also I replaced the exhaust donuts to stop a leak, but it sounds as if there is still one there. It also is on the driver's side. I have never had an engine too fail with proper maintenance and this one has been babied. A new filter and oil every 3,500 miles rain shine or snow. Okay you have my story and question so what motors will fit and does anyone have any idea what the knocking noise might be? If I pulled the oil pan would I be able to tell anything? Would it be cheaper to rebuild or replace?

 

96-98 should be drop in. Try to find one you can hear run,once done and bought,go ahead and replace the valve covers,oil sensor,and lower intake manifold gaskets. weak leaky points on these things. you'll be glad you did when its sitting on a bench.

 

I have a 95' Blazer with the same exact top end problem. What ever it is causes my oil pressure to be low (20) when idling and anywhere between 60-30 when on the throttle. When on the throttle it will usually stay at 40 though. It has had this problem for about 80,000 miles now and only disadvantage would be me never letting it rev above 3,000 RPM, never doing more than 65 on the highway, maybe decrease in millage??? and having to explain to your date that your car isn't broke...it's just not normal LOL. In that 80,000 miles with the knock she's only left me stranded once and it wasn't because of the knock but some bad gas. That being said if you get the exhaust problem figured out i'd just continue running her but do like i do and just be nice with the throttle. Keep up the maintenance and it should last a LONG TIME. I do the same maintenance as you and mine's got 290,000 with the original engine and only major work ever done has been water pumps!!