Bicycle Mechanics - Click-click when I push down left side crank

I have started hearing a clicking, almost rattling sound sometimes when I am pushing down on the left crank/pedal. It is very short, less than a second in length and stops when I stop pedaling. The sound seems to be coming from the chain ring and seems to disappear when I shift to the smaller chain ring. I changed chains just a few weeks ago, and the noise seems related, i.e. I didn't hear it before changing chains.

I assume that the new chain isn't integrating smoothly into the larger chain ring, but why only when I push down on the left crank? I have put the bike up on the stand and looked carefully at the chain and chain rings and see no clear problems. Also, when it is up, I am not able to reproduce the sound; so it must have something to do with weight/force on the cranks and chain ring.

The bike is the Dawes I bought from ebay last year and probably has 1500-2000 miles on it, as I trade off riding my older traveler quite a bit.

So, does anyone know what this sound is? And, if not, how do I proceed to accurately diagnose what is happening?

And for those wondering about the quality of the bikes from Chickabike/ebay, we may be starting to get an answer...

- Front derailer adjustment.
- Chainring warp.
- Cranks not seated.
- BB shell needs grease.

Thanks:

Front Derailleur seems fine, I checked it carefully and I don't think that's it.

Chainring warp: how would I check for this? it makes sense that at some point the chain and chain ring are not quite fitting and the sound is the chain clicking as it sits into the chain ring...warping could account for the sound.

Cranks not seated: here again I will need a bit of guidance. On today's 35 mile ride, the clicking became consistent with every turn of the crank, right or left pedal. The other sound that developed is a "crunching" type of sound when I push down on the left pedal/crank and exert some extra force (e.g. accelerating a bit or going up a hill). It doesn't happen every time, but once in a while.

BB shell needs grease: this too makes sense...hard to be sure the noise isn't from the BB and not from the chain rings or that I have 2 different sounds and need to sort them out. I haven't done any maintenance on the BB since i got the bike. I also suspect that the BB and crank ore one of the areas where lessor components have been used on this bike.

Thanks for the help...other thoughts are much welcomed and appreciated.

BTW, Lymbzero, I am down in Buffalo and get to Toronto quite often. One of my all time favorite cities, along with Chicago and London...