All of it. The 10 percent figure you occasionally see is nonsense that a lot of people believe just because they've seen it so much.
Quick Answer. Some things that cause a vehicle's front end to make a clunking noise are worn ball joints, a damaged tie rod, broken or loose sway-bar links, hard or damaged shocks, and faulty shock mounts. An automotive professional can inspect the vehicle's front end to locate the source of the clunk. Continue Reading.
Abnormal engine noise is due to excessive clearance between two internal metal parts that should have little to no clearance. This clearance can be due to many things from a broken valve spring to a crankshaft bearing that has failed. The first step is to identify where the engine noise is being generated. With the engine running isolate where the noise is coming from in either the the upper half, lower half, front half or rear half. Listen from above and below the engine as this will help determine where to start looking for the cause of the noise.