Mk2 slow cranking

[Diesel_Zuk]

Here is what I know: I was trying to start my 91 ecodiesel after swapping to a turbo pump, when one day, while cranking, the cranking speed suddenly dropped. I was confused, as I just charged the battery overnight. I checked all my connections, nothing loose, so I pulled the starter and took it to a shop and had it rebuilt. They charged me for brushes and a starter drive. Took it home, put back on, same thing, slow crank. I did not crank it for more than 5 seconds before looking online and seeing people say to replace starter bushing. Did that. Same thing. I put jumper cables directly from negative on the battery onto starter body as a ground. Then the positive onto the solenoid. Still nothing. I put a mk3 tdi starter on, still slow cranking, except I did not try jumping the tdi starter directly to the battery. Where do I go next? I can turn the engine over by hand with a ratchet on the crank, and it turns nice and easy, it's not locked up or anything. I checked timing, and rechecked timing, it's spot on. What do I check next?

[ORCoaster]

IF YOU DID THIS   

I put jumper cables directly from negative on the battery onto starter body as a ground. Then the positive onto the solenoid. Still nothing.

And haven't taken it back to the shop to demo the fact it isn't working then I would ask why not.  You paid for a serviceable starter and you don't have one. 

Time to go back where you spent your money and get what you paid for. 

[Diesel_Zuk]

It is better than before, but still nothing like it once was.

[LOBOTAC]

Check and/or replace your battery cables.  I had a similar situation after last clutch change, everything worked just fine prior to pulling it apart to replace clutch.  After reassembly, had very slow cranking.  I jumped with cables as you have from the battery to frame and starter.  Performed voltage drop check everything checked out normal.  Cleaned all grounds and connections.  I was pulling my hair out, it was driving me crazy that I couldnt figure out the problem.  Finally as a last ditch effort before towing it to a shop I replaced both cables from the battery and that solved all of the problems. 

[fatmobile]

Crank and crank or click and click for quite awhile.
 Then go feel for hot spots on the cable connections,.. both ends of cables.