Hi all,

I've needed to change my camshaft adjuster on the right bank. I removed the valve covers and spark plugs on the right bank.
I also removed the left bank valve cover but kept the spark plugs in place.

I removed the camshafts on the right bank and needed to turn the damper pulley to the 40 degree park after exploring each cylinder.
During this process, ie turning the damper pulley I heard a clunk noise just the once. What can this be?
The cams on the left bank are moving as normal. Sounded more from the right bank. I could also hear what sounded like air compression on the right bank. Any ideas?

Bear in mind the oil has also been drained so no oil in the sump.

Appreciate any thoughts. Will be putting the car back together on Saturday and just curious to the sound in case I may have damaged anything.

Oh and I forgot to mention currently the pipe going from the thermostat (coolant one) to the coolant reservoir has been removed.
Some mechanic broke it off before and decided to superglue it back which came off when rotating the damper pulley with breaker bar. Which meant coolant poured out from the broken nipple.

This could be the reason behind the sound. Maybe air compression in the engine?

Thanks for the response in advance lads!