I have a 98 12v cummins. I recently did some work to it and now it turns over real slow and and takes about 20 sec of turning over to finally start up. I'll fill you in on what all i did to it.

I tabbed my KDP inside the timing cover and added new gasket. Tightened all case bolts to proper torque. (REQUIRED: Taking fan off, belt, harmonic ballancer, radiator, etc).

Replaced belt.
Replaced both batterys.
Replaced fuel filter.
Replaced radiator (new fluids) Flushed.
Changed motor oil and filter.

It almost seems like it could be out of timing but I didnt think that was possible unless turning the bolts to take the ballancer off would have possibly done something.. It almost acts like its starving for fuel but at the same time its turning over slower than normal. The batterys were the duralast gold ones that autozone recomended. I can get a size on them if needed.

I also think my battery terminals could be shot, they are a little carroded and one its cracked a little so possibly both batterys are not being fully used.

But Im just looking for some opinions.. Thank you!!

 

i hate electrical problems checkall your contacts

 

Sounds like a bad battery. make sure the battery post are clean and making a good connection. check your ground too. more than likey its the battery

 

Thanks guys! Checked everything and turns out it was the starter slowly going bad.. Replaced it and everything works great!