[Kraftwerk]

Yes, it has a thermostatic acutator.

However, I have since solved the issue.

It turned out that it was caused by multiple things going wrong in the same time, and, together with me insisting on driving it almost daily it lead to a complete destruction of the top part of the engine.
An expensive lesson, especially considering that I rebuilt the engine ground-up a little over a year ago and put less than 20k kilometers on it.
Though I didn't pay enough attention to the head, as it turned out a couple of weeks ago.

To my understanding, this is what happened:
Engine was constantly "running" out of phase because cones on the belt-sprocket on the front of the cam was pretty much done. Furthermore, main crankshaft pulley's central wheel was ruined, along with the sprocket (probably wasn't tightened enough at some pont) so it had some play...enough to ruin the cam's sprocket enough to let it completely slip out of phase, as if the belt broke.
The end-result was pistons catching up with the valves and destroying them.
So I took the head apart, expecting broken pistons or con-rods, but ot was all fine.
Though...cam broke in half, all 12 valves were scrap, along with valve-guides and adjustment plates (as my head doesn't have hyrdaulic lifters).
Basically, every removable part in the head was replaced with new (except for cam-bearings, of course, and the cam alone, which I had to source used), head was machined and placed back on the engine with new Victor Reinz metal head-gasket, new intake and exhaust gaskets, cam "semmerings" (o-rings?) and cam sprockets.
Also, new cam-pulley assembly, new VE pump O-rings and setting it up correctly, injectoors check (they turned out to be just fine, but I plan to replace them some time soon as a mean of precaution).
I also took the opportunity to flush oil and coolant, clean the radiator and engine bay in general.

This lesson in D24TIC maintenence did cost me arount 650$, (converted to $), but I'd like to consider it a well spent money, since it is now running smoother then ever with significantly more power.