Running engine without serpentine belt.

Just a quick question.

Im struggling to track down a starting issue. I would like to remove the serpentine belt and try start the engine without the alternator being driven on a 300tdi. This would rule out a seized up alternator. I know the chances of it are slim but its still a suspect at this point. The other being a baked starter motor.

I've read up on how to get the belt off and back on. Just wondering if its safe to run the engine for a few seconds without the belt?

no issues, but it does drive the water pump so don't run it for more than a few mins from cold

An alternator isn't going to stop your motor starting though. Sweet f all resistance compared to what starters pushing out.
I'd look at weak motor or battery

With the engine off, I've 6.4k ohm through the D+ wire. That connected to my isolator lead to the battery's death and its now a door stop. I can understand the dash light wire acting as a neutral while the engines off but not the D+ wire. Which to my knowledge connects into the +12v for charging.

I searched on the forum and there are a few threads with seized alternators. Thats what got me thinking.

With the alternators wiring removed from the 12v side. When I try crank the motor I get a very sluggish turn. 12v drops to 7v. I've tested the engines earth, checked all wiring for any damage and found nothing.

So its lead me to think what I've posted originally. Id much prefer it to be the alternator as the starter looks a mission to swap out in comparison.

tbh if the alt was that bad id be expecting the belt to be skipping or squeeling

Looking through a few starter motor swap outs, I have noticed a missing earth. I dont have this earth coming from the motor.



Hoping this solves it, if it doesnt its serpentine belt removal. I still cant understand why the alternator's D+ has such a low resistance.

Starter earths through the metal casing to the flywheel housing.

try assisting earth cable which may be poor even though they look good with a jump lead to - on battery to transmission or engine