You shouldn't need the primer pump for a filter change. Try cranking it and that old gal should push through the bubbles. Also, do you use an additive in your fuel? I always run Diesel 911 (there are many brands and I'm sure someone here will ring in on their favorite to give you some other ideas). If the filters are a gunky issue, then the lines will have some build up, the tank will be cruddy, etc. A diesel additive will help clean the system and remove any moisture.

On the vacuum, you mention earlier in this post that you want to tackle that system and get it to the bare minimum to see if it changes the shifting. With that one nipple capped off, that is the bare minimum I'm afraid. The first place to start is to replace that line from the pump to the booster. That's about $30, and very well worth it. Also, the rubber connectors look cracked. Those little b**tards can drive you nuts of one of them is leaking. That's an annoying and surprisingly expensive job (I think that was about $30ish, too, but for dang little rubber bits, just felt like a lot!) but also a very good idea. I learned to do that with the first one of these I bought and have saved myself headaches by doing it on all of them right off the bat after.

Another thing to look at is the ALDA system. Here's a great walkthrough on cleaning a banjo bolt and line that gets gunked up over time. We did this on our rust...I mean...wagon and BOY what a difference that made on shifting and just general happiness of the vehicle.

Mercedes ALDA boost system service

Good luck!

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Current:
1980 300D "Blush"
1985 300TDT "Walter"
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Greatly missed:
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1983 240D "Dee"

are you in Galveston?

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Is it really safe to crank the air out of the filter without priming beforehand? I don't want to end up with air further down my fuel system. As of right now, the filter is only about half full (see attached photo)

Attached Thumbnails

 

Did you replace both filters? Or just the small one? I know you posted a picture of the large spin on filter but I didn't quite catch if you had actually installed it yet.

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1979 300D 040 Black on Black - 1985 300D Maaco job (sadly sprayed over 199 Black Pearl Metallic) on Palamino

http://i.imgur.com/LslW733.jpg

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Haven't installed it yet. Waiting on the o-rings and Diesel Purge to get in before swapping the spin-on out. The old one Should still be full of fuel.

Then it's fine to just crank to start. There's very little air in the pre-filter. Also, you will find that it is never really full of fuel, there is always a small pocket of air in there.

The large spin on filter is another story. You should fill that up with fuel, fresh motor oil, veggie oil, diesel purge etc (combustible fuel of some kind basically) right to the brim before installing it. And then pump it up with the primer as well.

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1979 300D 040 Black on Black - 1985 300D Maaco job (sadly sprayed over 199 Black Pearl Metallic) on Palamino

http://i.imgur.com/LslW733.jpg

The Baja Arizona Oil Burners Send a message if you'd like to join the fun
Left to Right - UberWasser, Iridium, Stuttgart-->Seattle,, mannys9130

Visit the W123 page on iFixit for over 70 helpful DIY guides!

Great. thanks for the tip. If she starts back up, the inline filter will have been the primary problem. If not, then onto bigger challenges.

She's back from the dead! Blew out a huge amount of smoke upon starting (scared the neighbors off their stoop), then idled rough for a little. Shut her off, started her back up and no smoke on the second round. Still not as smooth as before, but I've only let her idle for a couple of minutes.

Good to know that it was such a simple problem. I think I'll continue to go ahead with the replacement of the spin-on filter, diesel purge and certain leaking fuel return lines, just for the peace of mind.

The picture looks like one of those giant in-line fuses used for monster stereo amplifiers. That would likely have been connected directly to the battery or the output of the alternator.

Wow, that pic really shows how bad off the main vac line is.. I didn't know both nipples were jacked up.

My advice, considering all the good information posted already, would be to grab some StarTron tank cleaner. It breaks down a lot of the gunge that builds up in the fuel tank. A benefit of that is that the guide wires for the fuel sender will be cleaned somewhat and give your fuel needle a considerably more accurate reading.

Fuel Sender 85 300D- Cleaned (Pics)

Star Tron

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1977 Red 240D ( Squished by a 18 Wheeler )
1976 Black 240D ( Sold )
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1987 Black 560SEL ( Sold )
1983 White 300SD ( Sold )
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2014 Red Chevy Cruze Diesel ( New Hotness )

Looks like it might be a power cable for a stereo amp or maybe some kind of old two way radio

Yep your main vac line is in really bad shape, make that the number one thing to replace.

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The red wire in the fuse block is not a jumper, it's a power feed for something under your dash...

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