I have a 2002 F350 7.3l with 170,000 on it. New batteries last September, been super happy this year with how it has been starting in this Minnesota winter. Last Saturday drive it to the cities, 100 mile round trip. Turns over like a raped ape. Sits for 4 days, go to start it on Wednesday and the thing barely cranks. Sounds painful, but does start. Bought a load tester, batteries both test great 850cc amps. Driven a few times, always starts, but there dang near a pause between the painfully slow cranks. What may I be looking at here? I'm guessing my starter is dying? What do you all think? Can a starter just go to crap that fast?

 

check all the connections between the batteries and the starter, both power and ground. take them off, clean them [both the connector and the mount], and reinstall making sure it's good and tight.

after doing this, and the starter still doesn't really turn the motor over well, then it's probably the starter.

 

What Davester250 said is exactly what I would do. If you do need a new starter after cleaning the grounds and positive connections, I would look into the DB Electric starter at the link below.

 

Same exact one when mine started going out... After spending way too long figuring out how to squeeze the sucker in there, I got in, started up and was actually scared when I cranked.

It's THAT powerful.

Now it sounds normal and a regular starter just sounds wimpy.