Hello guys! I just wanted to gets ideas of what the possible cause of my blazer's knocking could be. The short story is I was driving home from work and the engine developed a light tapping noise which turned into a loud knock by the time I got home (10 miles). When I turn on the engine it sounds like a wrench knocking on metal. During the drive I did not experience any power loss or oil pressure drop. It's pretty much knocking that sounds likethe top half of the engine. I haven't driven it since that day a year ago. Any ideas would be welcome and if possible estimates if you know. Thank you all.

 

Welcome to the forum.
If you have a light ticking or a loud rattling, it's probably in the rocker arms in the top end..
If it's a loud solid knocking, it's probably in the bottom, crankshaft or connecting rod bearings.
If you know a mechanic or someone with lots of experience with engines, it would be helpful if you could get them to listen to it.
The quicker the diagnosis the better. If you have to run the engine for a long time to pinpoint the noise, the damage may be increased.

 

Really simple to check rocker arms is to remove the valve covers off of the heads, you should have either four small bolts around the perimeter of the cover or 3 nuts in the center. Remove these lift the covers off and check to see if any rockers have shifted out of place. It is very confusing that you claim that no power was lost, generally when a part fails with loud knocking there can be rough running at idle or part throttle cruising even with a rocker or collapsed lifter... If the claim is true then some other rotating part on the engine has failed clutch fan, water pump, power steering pump, belt tensioner or idler pulley. Might also be something in the transmission, bolt coming loose and knocking on another part....