300tdi oil exiting from unit below air filter

oil is gushing out of a unit fixed to the engine block just under the airfilter and behind the manuel fuel pump. This unit has a hose connection to the brake servo. There seem to be two protrusions on the circular vertical face, the top one is plugged, the bottom has no plug and is from where all the engine oil has escaped. I am new to 300tdi engines, any advice greatfully received..What is it called .. is this a serious problem .. what is its purpose .. sorry i cant get the picture to upload

Photo file may be too large, reduce the size by 50% and it should upload.

have a search on here for vacuum pump oil leak it looks a common problem

This should come in handy.

I just replaced mine last weekend. £80 from Bearmach. Simple enough job but fiddly.

Pity you were not closer too me in sunny Scotland, I have a new one sitting here

Thanks everyone.
My big question is..why did the bottom plug on the vacuum pump fall out? Is it under high pressure..could there be a blockage somewhere in the oil lubrication gallery?

When I took the old one off the cap was still on but there were traces of oil where it had been weeping from the same place yours is leaking. I don't know the internal workings so can't say what the problem was but I bet it's not uncommon.

Thanks. Did you replace yours with 2 gaskets or just one?

Just used one. They are quite thick. No leaks so far!