I replaced both of the filters in my 1985 Mercedes 300D and now my car won't start.

The replacing of the filters was easy, but then when I tried to prime the filter to bleed the system I had trouble with my primer pump.
The pump is the original style with the white knob.
The priming filled both of the filters, but I think there is air somewhere in the system.

When I pull the pump out fuel spills out from the pump itself, but no fuel spills out when the pump is locked. Does my pump need to be replaced?
Even though fuel comes out, the pump did fill both filters so it sounds the pump can't be completely shot.

So now my car won't start, and I'm afraid to just crank on the starter for fear of blowing the starter or killing the battery.

Any ideas on methods to getting this issue resolved?

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1985 300D, 112k miles

Crack the lines at the head & crank the engine. Re-tighten once fuel is coming out then start. Perhaps confirm that fuel is in the large filter.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Yes, your primer pump needs to be replaced with the new spring loaded style. And, you don't need to use the primer pump if you fill the secondary filter with a burnable liquid like diesel fuel, ATF, Purge etc, before installing it.
I'd replace the primer pump, pump the new pump about 100 times and see if you can get the air out. If not you might have to bleed the hard injector lines to get air out of the IP.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Ok, wow am I stupid. I went out to try cranking the car again and just hadn't been cranking the starter long enough. I cranked while holding the gas pedal down and after about 10 seconds of cranking it fired up. I drove it through the neighborhood and it drove fine, but now it won't turn off. I had to press the stop button. I checked and the brown cable above the oil filter housing is still plugged in, so any ideas on what this issue could be?

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1985 300D, 112k miles

You dislodged or broke a vacuum line somewhere. Are the brakes working ok? If so, it's not the main line but a branch line.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Sounds like you pulled a vac hose loose while changing filters, causing the no shut down problem. Look around in the engine bay for a loose vac hose or a broken connection.

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The brakes work fine, no noticeable difference in power, or shifting. Any other ideas on what this could be? I looked in the engine compartment and couldn't find anything unhooked or broken.

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1985 300D, 112k miles

Check the power door locks and HVAC system for proper operation.
Perhaps your shut off actuator, or ignition vac switch failed coincidentally, pull the brown vac line at the actuator and check for oil.

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83 SD

84 CD