OK, humor me. I haven't seen anything in your posts where you've actually removed the cables from the battery. So, try removing the cables and connecting the jumper cables directly to the battery posts. Do your "spark test" and if you get the expected spark, the battery is probably ok. If so, clean the battery posts and inside the cable terminal clamps where they contact the posts with sand paper or wire brush. Reinstall the cables to the battery and try to start the car.

If no sparking when attached directly to the battery posts, the battery is defective.

__________________
-Louis

'87 300D Anthracite

Next plan of action was to clean ever ground and posts. Kind of busy running sound at church at the moment.

Priorities man! PRIORITIES!!

__________________
-Louis

'87 300D Anthracite

Loosebenz
Hi can't recommend a shorting a batteryt. That is bad science. Otherwise battery terminal cleaning is good advice. Hope you are not offended.

__________________
85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.

Is the shifter sloppy and loose? Did you check the shift linkage bushings? Try and push the shift handle all the way forward and to the upper left. May have to try it a number of times. Not sure if the check on the neutral safety switch would have caught this or not as your nss is fine and the linkage is in limbo because the bushings are probably severely worn or my guess there are totally gone as in non existent. Your earlier post stating it started just fine several times has me leaning heavily in this direction. Had this happen very recently. Thought it was a dead battery as well with the no start, not even a click.

Wrong terminals. Jump the small phillips screw to the adjacent large phillips.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I'm doing it from my iPad. Lol.

I've had the same problem with two of my 123's. Both required the same repair which solved the starting problem. Assuming the battery is good and has enough current to turn the starter motor, and if you can jumper the starter with a screw driver from the purple wire connection and the starter engages then assume it works, then the battery has enough power to turn the starter. This tells you the high current side works. So next turn attention to the low current side of the circuit, ie the key ignition switch and the neutral safety switch. In my case the shifter was not completely allowing the shifting linkage to properly allow the neutral safety switch to dis-engage. The result was the car would not start by the key. The fix was replacing all bushings in the shifter and shift linkage arm. Cost about $8.00 from peachparts.

I private messaged my phone number

Not offended, but since he had already done it as stated in the original post, it was clearly something he is familiar with and knows the dangers.

__________________
-Louis

'87 300D Anthracite

What's the patients status?

Cleaned the posts and connectors and they shine

Checked voltage while cranking and when turning the key it drops to 11. Weird

Attempting to jump the car and starting it does nothing. No click from the starter.

When I jumper the terminal block the glow plug relay clicks.

Bypassing the NSS does nothing. No click from starter.

I attempted to adjust the alternator let a few days ago but I did not hit any wires or disconnect anything. The bulb for the battery light works too.

If the starter bendix was stuck it would still click if I'm not mistaken.

Keep trying the shifter by pushing forward and upper left. Is the shifter loose and sloppy?

Shifter is tight. It has new bushings.