As part of a long term rebuilding project, I've got the car garaged and am getting things back into running condition.

Today though, after starting the engine, I noticed smoke coming from under the brake booster. With a flashlight, as best I can tell, it's emanating from directly under the booster.
Nearly impossible to see the source though.
I noticed that stopping the engine didn't stop the smoking. It took my turning the ignition key completely off to stop it.

So, question is...does anyone have any ideas of what might be causing this?
I've not done ANY work in that area. Ever. It looks like trying to get some 'eyes' down there is not going to be trivial either.

__________________
Chris
1985 300SD - 'Grace' (198K mi.)
2018 Honda Civic Sport
2018 Honda CRV LX
2010 Honda Fit Sport (RIP)
2013 Honda Accord Sport (Sold)
1996 Lexus LS400 (Retired)
1995 Ford Contour SE (Retired)
1976 Porsche 914 (Sold)
1972 Datsun 240Z (RIP)