Hi all
I got the following explanation from the airplane factory. It fits very well what you all told me. But what is the optimum water temperature? Do any of you use a thermostat on the water system?
Kind regards, Claus
The function of oil thermostat is to open and close the by-pass line of the oil radiator. In case the oil is cold and so with higher density, then more oil is circulating via by-pass line (because of oil radiator resistance). This effect is leaving away and more oil starts to flow through the radiator step-by-step when the oil is warming up and the density increases. If the oil temperature reaches 86°C, the by-pass line closes and the oil has to flow only through the radiator.
Such solution is made due to safety reasons, because in case the oil thermostat fails, the line supplying the oil into the engine must be kept open to enable oil circulation via engine and so to avoid the engine failure and its damage.
The effectivity of the oil thermostat is not the same as it is at water thermostat, which can close the cooler completely. If the engine is effectively cooled and actual engine performance is not high enough to warm up the oil up to 86°C, the oil temperature stays low. The oil temperature is measured behind the radiator, in the area of oil inlet into the engine. It means the temperature of the oil inside the engine is always higher than indicated values.
Immediatelly, just after landing, check if the by-pass line of the thermostat is warm. The radiator should be significantly colder than that line. Both are reachable by hand from the bottom side of the engine compartment, so you do not need to remove the cowling to touch it.
I would recommend following:
- partially cover the oil radiator and partially cover also the water cooler
or
- to install/add water thermostat as to increase the cylinder head temperature and so to increase the oil temperature too. I can see on your photo that the water temperature is also low.
