Mercedes: 1977 300D vacuum line?, vacuum line, leak down test

Question
There seems to be a connection for a vacuum line on a part just above the injection pump. If this is a vacuum line, where would this be connected? Or is this just a vent? Mine is just a hard starting car and I have to depress the gas pedal to start the car.
Thank you for your time.

Answer
Hard start check list:
#1. Replace glow plugs with NEW.
#2. Replace both fuel filters.
#3. Look for and replace any leaking fuel lines.
#4. Adjust your valves every 15000 miles.
#5. Test battery and replace starter if it does not crank fast as idle speed.
#6. If it is still hard to start, have an engine compression and leak down test done by a diesel shop.

I suggest you join http://www.mercedesshop.com
http://www.mercedesshop.com/shopforum/forumdisplay.php3?f=15
Start a thread in Diesel Discussion and post a digital picture of the problem area.

Oh, please do not call it a gas pedal, some people get offended if you call it that, accelerator or throttle are ok.