ABC Bee engine

Now that my previous project is more or less at an end I can at last start looking at the Bee V4

there is an oil heating coil in the sump, next to this is a 3/8 BSP tapped hole with a 3/8-3/8 bsp adaptor fitted in it, looks like it may have been connected to an oil tank for adding oil? There is an oil pressure gauge already connected to the oil pump outlet so it’s not for pressure… any ideas ? 

Ps I added the hose to stop leaks when I filled it with oil!

 [attachment=1128]IMG_6774.jpeg[/attachmentCan anyone give me details of a starter motor assy I can fit to the engine, the pull start is a bit of a slog! I have seen a starter jury rigged before I’m sure…
 

Alex. Are you asking what the electrical connector is attached to?  Is it your understanding that it is unlikely to be oil pressure?  Will it be a thermocouple?  This is a APU out of a Bristol Beverly yeah?  So the oil heater would be for arctic operations? Do we have a manual? Br Neil 

beverly APU IT IS!
I do not have a manual for the engine I guessed the oil heater was for keeping Oil warm during shutdown, I was asking about the connection to left of the oil heater?

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I'm suggesting it's a thermocouple, the oil heater will need to be switched off when it's up to temperature (I think it's heating the oil prior to a cold start up when operating in the arctic). So the thermocouple will likely be wired into the circuit to prevent overheating. What's the relative sizes of the cable going to the heater coil and the size going into the plug?  If the same then I say it's likely a thermocouple wired in series. That would have been reliable.  Br Neil