Engine Rebuild Guide, Break-In and Tune-Up Preliminary Engine Testing Before Tune-Up Before tuning-up an engine, determine if a tune-up will restore operating efficiency. If in doubt, the following preliminary tests will help determine if the engine can be tuned-up. Choose from the following procedures only those necessary to restore the unit. 02 010 22 1. After engine has stopped for several hours, loosen crankcase drain plug and watch for any water to seep out. A few drops could be due to condensation, but any more than this would indicate problems which require engine repairs rather than just a tune-up. 2. With engine stopped, inspect engine coolant for oil film.
With engine running, inspect coolant for air bubbles. Either condition would indicate problems which require engine repairs rather than just a tune-up. 3. Perform a dynamometer test and record power output. (See DYNAMOMETER TEST in Section 04, Group 150.) Repeat dynamometer test after tune-up. Compare power output before and after tune-up. DPSG,OUO1004,921 –19–07NOV00–1/1 CTM100 (06APR04) 02-010-22 P OWER T ECH 10.5 L & 12.5 L Diesel Engines 040604 PN=70