https://www.youtube.com/watch?v=49AxSbketSw&ab_channel=KaiFootikum
Fra video:
Now I got it fixed! Does your coolant disappear from time to time? Mine disappeared, at the beginning, I had to pour some coolant in a one or two-month interval. It depended, how aggressively I drove. (on road trips at speed 140km/h I had to pour coolant quite often). In the end (before I got solved) a couple of times per month. In my case there was a micro crack in the upper engine block, coolant got into the first cylinder, it also killed a glow plug, which is quite important in winter for ignition. So the first thing you should try is to check engine compression and are your glow plugs moist, they shouldn't be. If so, consider save some money or sell the car. PS. this case might kill EGR too...