I had same issue with my Hijet Cargo 2008 model. Your engine compression is low and that is why its giving you problem.
The oil do not reach tappets and make them jam and you have to keep the oil level higher than the top mark on oil dip stick to keep the tappets oiled and reach to higher points, that's what my mechanic said.
Your engine needs tappet adjustments and also rings need to be fixed if there is any air passing through.
Thanks.