Cleaning coolant expansion tank

[Legojon]

So, thanks to a cracked head gasket I now have residual oil floating in my coolant tank. This troubles me and I'd like to get rid of it. I had much fun with a turkey baster (but that's another story). Needless to say, the only way looks to be to disconnect the inlet and outlet and remove the tank. Trouble is, surely that will trap air in the end of the inlet pipe when I replace it!?

I'm sure I read somewhere that the system is "self bleeding" and would work the air out itself. But... before I crack another head gasket, does anymore know if this is true? Or a better way of doing it?

Here is a picture of some oil in an expansion tank (sensitive members should look away now).

 

[Legojon]

So, I couldn't really find out what to do. I don't have pics because it's not really a difficult job. But...

I just clamped off both hoses. Removed the tank, cleaned it. When I replaced it I topped it up really slowly (trying to avoid getting air in the pipe). Topped it up to the max line. Then I ran it without the cap (heater on full heat, fan on minimum - if you go lower than 1 the lot turns off!). Waited until 50 degrees (when the thermostat opens). Gave the bottom pipe a bit of a squeeze for good measure.

After all the above, I switched off. Put the cap back on. Took it for a run. Next morning I had to add about 200ml, and it's stayed at max since. So I would say job done.