Preventive Maintenance
will depress the belt 1/2" to 3/4" If belt tension gage
grease at the grease fittings. At temperatures above
BT-33-73FA or equivalent is available, adjust the belt
+30F (-1C), use a No. 2 grade grease. Use a
tension as outlined in Table 2.
No. 1 grade grease below this temperature. Lubricate
all other control mechanisms, as required, with engine
NOTE: When
installing or adjusting an acces-
oil.
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.
Item 19
There is no scheduled interval for performing an
engine tune-up. As long as the engine performance is
Adjust Poly-V Fan Belt (16V-71)
satisfactory, a complete tune-up is not required. Minor
adjustments in t h e valve and injector operating
The fan belt should be neither too tight nor too loose.
mechanisms and governor should only be required
Carelessness in making a belt adjustment can be
periodically to compensate for normal wear on parts.
dangerous. Too tight a belt imposes an undue load on
the fan bearings and shortens the life of the belt. Too
loose a belt allows slippage and lowers the fan speed,
causes excessive belt wear and leads to overheating of
Item 20
the cooling system.
New standard V-belts will stretch after the first few
hours of operation. Run the engine for 15 seconds to
Before a Poly-V belt is installed, it is very important
seat the belts, then re-tension them. Retighten the fan
that the crankshaft pulley (10 grooves) and the fan
drive, pump drive, battery-charging alternator and
drive pulley (11 grooves) are in alignment. The extra
other accessory drive belts after 1/2 hour or 15 miles
groove in the fan drive pulley can be on the inside or
(24 km) and again after 8 hours or 240 miles (386 km)
the outside of the pulley, depending upon alignment
of operation. Thereafter, check the tension of the drive
requirements.
belts every 200 hours or 6,000 miles (9 656 km) and
adjust, if necessary. Too tight a belt is destructive to
Misalignment between the crankshaft pulley and the
the bearings of the driven part; a loose belt will slip.
fan drive pulley cannot be more than .009" per inch
o f center line distance. A straight line can be
Replace all belts in a set when one is worn. Single belts
determined by placing a straight edge on the rims of
of similar size should not be used as a substitute for a
the pulleys. A spacer is available to facilitate pulley
m a t c h e d belt set; premature belt wear can result
alignment, if necessary. The spacer mounts between
because of belt length variation. All belts in a matched
the crankshaft pulley and the vibration damper hub.
belt set are within .032" of their specified center
distances.
Poly-V belts require a special procedure for proper
belt tension.
Adjust the belt tension so that a firm push with the
thumb, at a point midway between the two pulleys,
1. After the belts have been initially adjusted, run the
engine under a light load for one-half hour.
"V" and "POLY V" BELT TENSION TABLE (1 lbs-belt)
2. Stop the engine and check the belt tension with the
Alternator or
belt "hot"; use belt tension gage BT-33-86AE6-40A,
Fan Drive
Generator Drive
or equivalent, which has a range of 60 to 400 pounds.
One
Two 3/8"
8 Rib (K)
10 Rib (L)
2 or 3
Single
Poly V
Poly V
1/2"
or 1/2"
3. If the tension value is not between 280 and 360
Belt
Belts
Model
Belt
Belt
Belts
Belts
pounds, re-adjust the belt tension.
50-70
110-130
40-50
60-80
80-100
6, 8V-71
CAUTION: Because the allowable load the
50-70
12V-71
70-90
40-50
crankshaft bearing can carry is critical, do not
40-50
50-70
16V-71
310-360 90-120
exceed the maximum tension value of 360
pounds.
Belt tension is 50-70 far a single premium high capacity belt (.785"
wide) used to drive a 12 cfm air compressor.
4. Run the engine at full load for eight hours and then
Adjust all V-belts with belt tension gage BT-33-73 FA or equivalent.
recheck the belt tension.
Adjusr all Poly V-belts with belt tension gage *BT-33-AE6-40A
(Burroughs) or equivalent J23586 (Kent Moore) *Range 60-400 lbs
5. If the belt tension is too tight or too loose, keep the
gage in place and adjust the belt tension, to the
TABLE 2
prescribed value, a t t h e a c c e s s o r y m o u n t i n g o r
Page 69
