Hello cobbadog, sorry it's taken me so long to reply. I'll send you a private message. Thanks so much. Btw, I've solved the problem now, I simply need a soldering nut and nipple. I got the answers on another forum, I'd share the link but I'm not sure it's good etiquette to share links to other forums with the same question where others have replied.

Hello, newcomer here. My names Jim, I'm based in the North West of England, I have a narrowboat called Sin Prisa. It's an unusual name and means 'No Hurry' in Spanish, I was thinking of changing the name but it's grown on me and I like its originality. I purchased the boat in 2019, it needs a lot of work doing to it and as I was new to narrowboats at the time I'm having to learn much about boats such as the DC electrics, the engine etc... Btw, my engine is a Lister SR2 with a LH150 reversing gear. Now for my first request for help, I hope this is an appropriate place to post this. Please have a look at the included photos. I'm wondering what this actually is and where it connects to, the second photo shows the disconnected pipe. Research suggests it's a pressure gauge. I'm also not sure what the tap to the right is for, it seems to release oil. Thanks in advance for any help anyone can give.