The coolant is running low and the left headlight is fogging up

[tyc]

For a while now, the left headlight has been fogging up. I took the headlight apart to look for the crack/break but it's intact. I took the lens apart and insulated it with gasket paste. And it's still fogging up. So the fogging up of the headlight has a different cause than the leak.
In the immediate vicinity of the headlight is the radiator expansion tank. The expansion tank cap is fitted with 2 valves so it could be faulty but I have one, I'll replace it and if the problem persists it's the radiator or its hose joints. I have a replacement radiator but I don't know if it's suitable: it's 000 3428 V006 and the engine is 0.8CDI. I searched the internet and it gives two codes for the same engine - 000 3428 V006 and 000 3428 V007.
I wonder which code is the right one?
on a Smart 450 CDI 2000 I replaced the electric block of the engine 000 2351 V006 with a 000 2351 V007 taken from a 450 CDI 2000 and everything worked well until I noticed that the glow plug bulb would not turn off. I asked MB Star and indeed the glow plugs were active as long as the engine was running but without other problems..

[tyc]

I found the 006 radiator and replaced it, but the headlight is fogging up like before. Now I'm going to cover the headlight with aerosol spray the next time I remove it.