How to open bonnet on a 1980 mercedes benz 300 D

The hood release is a red lever under the dashboard about shin height. I found the image on a Haynes online manual -
Opening the bonnet Mercedes Benz Class 2008 2011 Petrol B180 1 7

Lever is under the dash, flat to the panel and pulls down to release catches. At the front a plastic "tongue" sticks out from grille, pull on this and lift bonnet up. Note as all Mercs you can put hinges in second position so that bonnet is vertical for maintenance, engine removal etc.

With vehicle raised and supported safely turn the sticking wheel/s. Then open the bleed nipple for that caliper. If the wheel frees up then you most likely have semi blocked flexible brake pipes. Renew them all. If you have no luck let us know what you have tried/replaced so far.

well this is not easy unless you make a accessby removing anything in the way,or just take the headlight out ,How did you manage to open the bonnet as these vehicles from around this year started using a sealed bonnet that only the dealers can open with a special electronic key that uses rolling encrypted software.

diesel giant .com

El fuse #6 Mercedes 450sl w107 1980

1. whoever opened your pump obviously did not have the necessary knowledge call ''ROVAN DIESEL'' AND ASK FOR HELP. Tell them what you did and ask for help and next time make sure the mechanic you use has a diesel license.
   
   
   
   
   
   
   
   
   
   
   

Check the trans fluid level.  Is it dark and burned?  

It is a vacuum loss problem. Trouble shoot the vacuum system.