Toyota Repair: Excessive Crankshaft End Play, crankshaft pulley, thrust washers

Question
Background: I took my 2000 Sienna in to the dealer for in for its 1st oil change at about 1700 miles. When I picked it up, the engine was knocking. I immediately contacted the dealership and took it back in for the noise to be checked out. After inspecting it they told me the engine had been assembled with the wrong size main bearings and replaced them under warranty. When I just took it in for a timing belt replacement at 105K miles (a bit overdue), they told me the crankshaft has very excessive end play and I NEED A NEW ENGINE (so no point in replacing the timing belt).  I have done all oil changes as scheduled and have had no other engine problems. The engine also shows no symptoms of any problem other than the wear in the engine block from the crankshaft pulley.

Question: Is it possible the undersized bearings caused damage to the block that ultimately resulted in the engine failure, and might it be worth replacing the bearings, thrust washer, etc. to buy some additional time?


Answer
It's hard to say whether a new engine is needed without removing the oil pan to actually inspect the bearings and thrust washers, if the crankshaft or the engine block show any damage then the block would need to be replaced but if the thrust washers are worn and it was caught in time then it may only be necessary to replace the thrust washers.