DETROIT DIESEL 53
Preventive Maintenance
15.1
Item 19
There is no scheduled interval for performing an
engine tune-up. As long as the engine performance is
satisfactory, no tune-up should he needed. Minor
adjustments in the valve and injector operating
mechanisms, governor, etc. should only he required
periodically to compensate for normal wear on parts.
Item 20
New standard V-belts will stretch after the first few
hours of operation. Run the engine for 15 seconds to
seat the belts, then retension them Retighten new fan
drive, pump drive, battery-charging generator and
other accessory drive belts after 1/2 hour or 15 miles
and again after 8 hours or 240 miles of operation.
Thereafter, check the tension of the drive belts every
200 hours or 6,000 miles and adjust, if necessary. Too
tight a belt is destructive to the hearings of the driven
part; a loose belt will slip.
Replace all belts in a set when one is worn. Single belts
of similar size should not he used as a substitute for a
matched belt set; premature belt wear can result
because of belt length variation. All belts in a matched
belt set are within .032" of their specified center
distances.
Item 20
Adjust the belt tension so that a firm push with the
thumb, at a point midway between the two pulleys.
wilI depress the belt 1/2 " to 3/4" If belt tension gage
BT-33-73FA or equivalent is available. adjust the belt
tension as outlined in the Chart.
Generator Drive
Fan Drive
Item 22
Two 3/8"
or
One 1/2" One Wide
Engine 2 or 3
Single
At a major engine overhaul, discard the bearings in
1/2" Belts
Belt
Belt*
the fan hub assembly used in radiator cooled engines.
2 3, 4-53 40-50
40-50
50-70
40-50
6, 8V-53 60-80 80 - 100
40-50
50-70
40-50
Pack the huh assembly, using new bearings, with
Texaco Premium RB or an equivalent performance
All
For 3-point or triangular drive use a tension of 90-120.
grease.
*Belt tension is 50-70 for a single premium high capacity belt
(.785" wide) used to drive a 12 cfm air compressor
ltem 23
BELT TENSION CHART (Ibs/belt)
NOTE: When installing or adjusting an acces-
sory drive belt, be sure the bolt at the accessory
adjusting pivot point is properly tightened, as
well as the bolt in the adjusting slot.
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