recommendations for detroit diesel engine break-in
do not idle or fast idle
Detroit Diesel remanufactured engines have to be properly broken-in. For proper engine break-in do not idle or fast idle for more than 5 minutes at a time for the first 20,000 miles or liner and ring damage may occur and the warranty may be voided.
Break-in oil should be changed no later than 2500 miles.
run the vehicle hard
We recommend that you run the vehicle hard for 50 miles after the installation with no fast idle or no idling at all.
from the detroit diesel service manual
Stop the engine immediately if a leak or unusual noise or vibration is noted. Do not restart the engine until the cause of the concern has been investigated and corrected.
During long idling periods, the engine coolant temperature will fall below the normal operating range. The incomplete combustion of fuel in a cold engine will cause crankcase dilution, formation of lacquer or gummy deposits on the valves, pistons and rings and rapid accumulation of sludge in the engine.
Note: When prolonged engine idling is necessary, maintain at least 850 r/min spring/summer and 1200 rpm fall/winter.