What is this on the back of 200tdi intake manifold?

[supertreeman]

This was in a used 200 tdi that had a small length of hose attached to it and a big bolt plugging the hose. Classic UK mechanics..

What the heck is it?

 

[Napalm00]

Whatever it is I wouldn't trust just capping off that port.

You could knock the entire plug out of there and just replace it with a new freeze plug of proper size without some janky hole in it

 

[erover82]

Was probably feeding a boost gauge.

 

[KGH]

Nitrous.

Really cuts down those 1/4 mile times.

LOL