8.3L Cummins Diesel Engine Problems, Specs

The Cummins 8.3 is an inline 6 turbo diesel engine made from cast iron.

The engine is used in school buses, motorhomes, and trucks. It has a towing capacity of 20k lbs. Life expectancy is 350k miles, but can go further, as some have over one million miles.

Common problems reported are:

  • Block breaks after 7k hours
  • Valves dropping
  • Lift pump failure
  • Hard to start especially in cold weather
  • Throttle TV cable link breaks
  • High pressure pump failing
  • CAPS accumulator pump system issues


Video explaining details of issues:



The specs are:

  • 506.5 cu in (8.3L)
  • Turbocharged
  • bore and stroke, 5.31″ x 4.49″
  • Oil capacity of 6.3 Gallons
  • Weighs 1630 lbs
  • Torque 670 – 1,075 lb-ft
  • HP 240-400 HP
  • Cast Iron Engine Block and cylinder head
  • 22 qt oil capacity


The 8.3L is the larger than 5.9L and weight 2k lbs more. The 5.9 has more power.

A used 8.3 sells for $6k-$14k and are widely available.