Lifting it makes it much easier to turn. As far as the cap, you could remove it but it isn't necessary.
The idea that it was half empty again concerns me. It may just need bled. However, there could be other leaks. Since the noise wasn't there before you did the work, I feel that bleeding the system should help.
Let me know how things work out for you.
Saturday, September 27th, 2014 AT 5:51 PM