Single Click felt in left pedal near top of travel (left side)

[Dominover]

Recently I've noticed a dull single click sound, and I can feel it vibrate, in my left pedal. It happens when the left crank arm is almost at the 12 o'clock position every time.
I can't seem to reproduce it when turning the pedal or crank arm by hand. I also tightened the pedal up via the end nut so that the peddle spins nice and firm and there's no play at all.

I seem to have to have my foot on the pedal to make this happen, even when pressing very lightly the click is still there. It's a definite dull click but it's only one the left side of the bike.

The bottom bracket on this bike is a threaded VR sealed bearing that screws into the bottom bracket hole as one piece. When I try to wobble the crank arm on both sides there's no play at all. There's no play in the pedals now either.
I'm really not sure where the noise is coming from.
Just remember. It's on the left side only and the click happens when the left crank arm is in the same position every time.
Could this be from the pedal, or the bottom bracket?
Thanks

 

[Paulus]

It could be either really.
Have you got another left pedal to swap it with to try and eliminate that?
Also check for a slightly bent chainring, where the chain might be catching the FD.
Does it click on all Chainrings, or just one.
Try removing the BB , clean and regrease the threads.
These clicks can be a pain to find.

 

[geocycle]

Good advice above. You’ve just got to be systematic in locating clicks. Clips, pedal, crank, bottom bracket, etc. when a BB goes wrong it is usually gravely rather a click on each rotation. I agree about the chain rings and derailleur checks.

 

[boydj]

Don't forget to check the shoe and cleat.

 

[neil_merseyside]

And only change one thing at a time or you'll never know for sure what caused it.

 

[Dominover]

Thanks for all the answers.
I only recently remembered this happening after I loosened the crank arm bolts as I tried to get to the derailleur. It appears that I didn't tighten them up hard enough. I don't know how this would have caused the click, but it seems to be connected. After I tightened them right up (and it had to be very tight) the click has completely gone away.
The Bottom Bracket assembly is one piece on my bike. It's threaded, so the whole unit screws out.
I'm still not sure how marginally loose crank bolts caused the click but it's gone now.
Thanks for all the answers. I'm learning..

 

[gbb]

Just check your front derailleur cable isn't sticking out and catching the crank as it passes.

 

[biggs682]

Edge of fr mechanism touching crank arm had it many times but on right hand side not left

 

[Jameshow]

Pedal bearing?

 

[Paulus]

Does it happen when standing up on the pedals?
I have had annoying clicks which turned out to be the drawstring of my joggers pinging on the crossbar each revolution.
Have you got anywhere with swapping the pedals yet?

 

[MichaelW2]

Check the plastic toggle lock on the drawcord of your coat. Is it tapping the top tube when you pedal ?