Originally Posted by
T-Mar
Clean cogs and chains run noisier than dirtier ones. The build-up of oily dirt on the chain and cogs decreases the noise, by providing a soft layer than prevents direct metal on metal contact. It's highly unlikely that you got anything into the freewheel mechanism just by running the chain through the cogs. The noise is probably just the increased metal to metal contact of the clean chain and cogs. The noise decrease takes place so gradually over time that you don't notice the change, until you clean everything.
I've noticed that very gritty sound when I first ride after "cleaning" a chain, but I'm pretty sure it is just some of the remaining grit that now needs a mile or so of riding to get displaced away from the mating surfaces in and about the chain. Some of the grit also quickly breaks down to a size that can't be heard.
I try not to let it bother me, after experiencing this for so many decades! Chains are designed to digest a decent amount of grit in their lifetimes while still lasting a very long time.