[Maxxed_Ross]

yeah it's normally a problem with older engines

It is basically a sideways movement of the piston against the side of a cylinder bore. All piston driven internal combustion engines and compressors have a certain amount of piston slap. Excessive piston slap happens when the clearance between the piston and the cylinder bore becomes too great through wear, mismatched pistons and cylinder bores at manufacturing or, a combination of both. The noise associated with excessive piston slap is due to the impact of the piston against the wall of the cylinder bore, typically loudest when the engine is first started up. The pistons then expand with heat reducing the piston to cylinder bore clearance - reducing the impact of the piston against the cylinder wall and its resulting noise.

One way to check for piston slap is to remove all but one of the spark plugs, crank the engine over until you feel the resistance of the piston coming up on compression. Crank against compression until the piston is about half way up the cylinder. Now using the fan, rock the crankshaft back and forth and listen for a metallic clunking sound. Unfortunately with the V6 this might take a while, but will save you some hefty garage bills and potentially being told the wrong information again (most garages won't even touch suspected internal problems if they can help it)

If you hear a clunk, you have piston slap and the only way out is to rebuild the engine. Depending on how serious the slap is you might just need a new piston head, or it might mean a re-bore and sleeve if it is serious