Did that engine overheat? Overheating often destroys piston ring tension and ruins compression. Is this a Mitsubishi engine? Some Mitsubishi engines were more likely to have valve seals fail than other engines. Some versions of the Chrysler Town and Country van had 6G72, and valve seals would only last 90,000 miles (~145,000 KM). The Nissan Quest VG30E went much further without valve seal problems. Why are these valves in terrible condition? It is interesting that you hammer the valves to grind them in. In the USA, most people spin the valves to grind them in.
According to his last video, it's a 2016 Daihatsu K truck engine with 210,000 miles on it. I don't think he mentioned anything about overheating problem, but just doing overhauling so that he can use it as company car. He Also mentioned in his past video that compression on this engine was pretty good as is. I'm no mechanic, so I don't know what I'm talking about.
@@3decadesBehind Okay, thanks for the clarification. The rings looked weak and wouldn't hold compression, that's why I was surprised the compression was good. I know very little about Daihatsu engines because only a few were sold in the USA.