Starter Replacement 41MT 12-tooth

Our Cummins C8.3-325 engine has had hesitant / slow start issues for over a year. Many things we did seemed to make some difference, but the coach just did not start like it used to a few years ago.

Today we replaced our original starter with an new Delco Remy 41MT and our coach started better than EVER. We are happy campers.

Over the last year we:

Replaced our two Optima red-top start batteries.
Added a 3rd start Optima red-top battery when we replaced the two older ones.
Replaced inter-battery cables with bus-bars.
Added an additional 4/0 start battery ground cable.
Moved negative cables to first start battery and positive cables to last battery in parallel chain ( How to interconnect multiple batteries)
Rebuilt starter.
Rebuilt alternator.
Cleaned all ground and positive cable terminals.
Replaced all parts on isolator panel ( Isolator Replacement / Testing)
Reviewed the complete start circuit from ignition key to rear start solenoid, replacing some of the parts.
Added start battery combiners, like Trik-L-Start ( How to keep the start batteries charged).

Cummins originally gave us the incorrect starter part number and we started by chasing the wrong starter, but when we removed our original starter, we learned the correct part number from the plate. Then the game started to find our Delco Remy 10478818 41MT,12-tooth starter.

We removed and reinstalled the starter ourselves. Starter weighs 51 pounds and has a special 12-point small head bolt, which requires a small metric 12-point 3/8”-drive #12-size socket. Space is limited and a long extension is needed.