39
C.
BOLTS AND TORQUE REQUIREMENTS
All bolted joints are properly torqued at the factory and the cooler’s gasketed joints are
leak tested.
Before initial startup and as a regular preventive maintenance procedure, the radiator
should be thoroughly inspected for loose bolts.
A typical Rocore radiator may have many different types of bolted joints and torque
requirements; see the following subsections 1 – 4.
1. SOFT JOINT TORQUE REQUIREMENTS
These are the cooler’s tank/gasket/header joints. Upon the initial filling of the radiator,
you may notice some slight seepage around the gasket joints. This is due to the gasket
drying during shipping and/or storage. If this occurs, allow the gaskets to soak
overnight. It may help to run the system with the coolant under pressure. The gaskets
may swell enough to stop the leaking. If not, the bolts will need to be re-torqued.
Remove the fan or core guards and re-torque bolts in the area of the leak. All header
bolts should also be re-torqued at this time. The torque for these bolts should be 13 to
15 ft-lbs. Replace guards.
CAUTION! Do not over-torque. Over-torqueing may damage the gasket.
2. STANDARD HARD JOINT TORQUE REQUIREMENTS
Standard hard joints would be defined as metal-to-metal joints that are assembled with
standard hex bolts, nuts and washers. If any of the standard hard joints require
re-torqueing, use the values in Table 5:
Table 5: Torque to apply for standard hard joints
DRY TORQUE, FT – LBS
BOLT SIZE
GRADE 5
GRADE 8
1/4 – 20
8
12
5/16 –18
17
25
3/8 – 16
30
45
1/2 –13
75
110
5/8 – 11
150
220
3/4 – 10
260
380
3. STEEL BUSHING TORQUE REQUIREMENTS
For steel bushings to steel sheave hubs and steel fan hubs, use the values in Table 6.
The bushing type is usually stamped on the bushing.