TM 5-3805-280-24-2
Engine Tune-Up and Break-In
PRELIMINARY ENGINE TESTING
100
2
bubbles. Either condition would indicate problems
Before tuning-up an engine, determine if a tune-up will
which require engine repairs rather than just a
restore operating efficiency. If in doubt, the following
tune-up.
preliminary tests will help determine if the engine can
be tuned-up. Choose from the following procedures
3. Perform a dynamometer test and record power
only those necessary to restore the unit.
output. (See DYNAMOMETER TEST later in this
group.) Repeat dynamometer test after tune-up.
1. After engine has stopped for several hours, loosen
Compare power output before and after tune-up.
crankcase drain plug and watch for any water to
seep out. A few drops could be due to
4. Perform compression test (See TEST ENGINE
condensation, but any more than this would indicate
COMPRESSION PRESSURE in Group 105).
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
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