I recently got a engine block that looks great, 60k on it but I bought a new crankshaft, and upgraded engine parts. MY friend is telling me I don't have to get the block line bored, but to just replace the bearings...is that going to be a problem? new pistons, rings, seals, and crankshaft...used block. Of course I will get the cylinders done but is the main bearing re-bore necessary????thx
I would get it done just to be on the safe side and to make sure everything is true. An once of prevention.....
if its in specs i wouldnt get it line honed. a machnist once told me that the only time the is really necissary is either A. it is out of tolerances, or B. You have new main caps installed
I am assuming you checked the crankshaft main and rod journals when you did the bearing replacement. Since the knocking is still there it would seem possible the problem is with the piston in cylinder number three. The piston could have a bad wrist pin or a broken or collapsed skirt. A broken ring on the piston can sometimes produce a knocking sound, but often times it is not very noticeable. Unfortunately, it appears you are going to have to pull the head and inspect the piston to make a definitive diagnosis of the cause of the problem. Good luck.
A good machinist can check the crank bearing bore for alignment with a straight edge. You can also tell when disassembling an engine by looking at the existing bearings and their wear pattern. If the block is straight line boring is a waste of money and a possible new source of problems if it is done incorrectly. If you still have the bearings marked, line them up and look at the wear, if not have the block checked by an experienced machinist who already has plenty of work. Not always but many times line boring is an upsale for shops looking for more profits. It isn't needed very often.
