his W114 is a low mileage example which is unfortunately show a bit of rust in the fresh air plenum in the cowl .
Picture on the left is the right hand corner ,the insulation pad has been pulled aside to get a look at the damage. the right picture shows the inside with the hand brake mech on the side where rust has come through there too.
Before the rust is cut out 
1/2 way through the cutting process.
The Right side front guard has been removed to get access to the rust on the cowl. the hole at the top was caused by moisture getting into the weld seam over the last 50 years.
The whole rustyb part was cut out,revealing more rust inside the plenum which can only be accessed from the engine compartment. New steel is welded into place ,etch primed then zinc primed .This will be painted body colour and then wax treated.
The sound and heat insulating pad has been removed to expose the rust.
A bit hard to see here but the front panel on the cowl has been removed to expose the inside of the plenum. the grey is factory primer ,which was removed and replaced with etch primer then zinc primer ,to be coated with body colour and wax coated to prevent rust in the future .The Shiney grill is the fresh air intake and it allows water to get into the plenum when it rains. This has been removed to gain access to the entire plenum and repair spot rusting.
benzkraft 