I just bought me a 97 Disco 1 SE7 yesterday and long story short I got a little scammed. 4 codes popped up P0300 P0305 P1316 P0420. I drove it 5 hours back to where I live when I bought it yesterday and I swear I didn’t hear it misfire at all so I thought the code was a little weird. So I check the spark plugs and I did a compression test and Cylinder 5 was at 60 psi and the rest were above 150. So I poured a little oil down the cylinder to see if it was the piston ring and the psi went up to 90. So now I’m just a little puzzled, I find it odd that only one ring needs to be replaced and I’m hoping it might just be a blown head gasket. My question is can I replace the ring from the bottom and bypass taking the whole engine out and or has anyone dealt with this same issue. I’ve never worked on a Land Rover before so any helped or advice would be appreciated. I also put some sea foam and injector cleaner in her for ****s and giggles but could it also be the coil packs possibly?