While working on a solution to my air to oil cooler thermostat problem on my 2.0TD QSW conversioin I came across this:
Clockwise from top left: Valve in my 2.0TD oil distributor, thermostat (or waxstat) from the innards of that valve, internal portion of thermostat from an old 1.6TD, a complete 1.6TD thermostat.
A waxstat is just the control mechanism for a thermostat.
The 1.6 internal piece fits nicely into my valve and it may just solve the problem, it doesn't fit perfectly tight but it doesn't need to since there's spring pressure holding it in place. The bad/old one taken out was stamped 100 Celsius so I'll see if I can find one close to that temperature, for now I'm experimenting with a 90 Celsius unit.
There has to be a similar solution to the waxstat at the injection pump and I will be looking into this in the next few weeks when I install a new waxstat I purchased from Amazon UK.