The real cause of injector rattle?

[Ruan]

I've found on genuine stats (from testing with pans of water...), the thermostat will tend to start opening at ~80*C and be a bit open by ~83*C... The reason they jump a little when the thermostat first opens is because there's not much bypass flow to ensure the thermostat actually receives the hot water to allow it to open. Soon as the block water starts actually moving, the actual localised water temperature hits the thermostat housing which was full of cooler, slowly moving water up until the thermostat opens.

Correct that the TU3s do have an 89*C thermostat. Note that the GTi6 infact has an 83*C thermostat, same as a HDi.