Radiator Cap; Removal; Installation; Warm Weather Operation - Hobart 60PL20 Operation And Maintenance Manual

B. Radiator Cap

(1) General

A pressure valve is built into the radiator cap. It is designed to open at a pressure of approxi-
mately seven pounds per square inch.

(2) Removal

To remove, turn the cap to the left (counterclockwise) to the safety stop. When all pressure is re-
leased, press down on the cap and continue to turn until the cap is free to be removed.
WARNING: Hot steam and fluids will severely burn! when removing cap from a
very hot radiator, do not turn cap past safety stop until all pressure or steam
has escaped. use protective clothing. Allow engine to cool before adding
coolant.

(3) Installation

When installing the cap be sure it is turned clockwise as far as it will go so that the pressure re-
taining valve will be functional.
C. Warm Weather Operation
During warm weather operation, if water is used in the cooling system instead of an antifreeze solu-
tion, keep the cooling system free of rust and sludge by adding a cooling system conditioner that is
compatible with aluminum. Instructions for use of the conditioner are printed on each can.
CAUTION: Use only a corrosion inhibitor that is compatible with aluminum. do not use
inhibitors labeled as "acid neutralizer".
D. Cold Weather Operation
CAUTIONS: (a) Do not use "methanol" or alcohol as an antifreeze, and (b) Do not use two
different types of antifreeze. Mixed solutions (two types) make it impossible to determine if the
cooling system has adequate protection against freezing.
(1) General
A permanent type, (Ethylene Glycol) antifreeze is recommended for use in the cooling system.

(2) Checking coolant solution

Check solution frequently to be sure the cooling system has sufficient protection against freezing.
NOTE : (a) When testing the solution, be sure the coolant is at operating temperature. (b) Follow
manufacturer's instructions on tester.

(3) Preparing the coolant solution

The following table (Figure 2) indicates the freezing points of solutions varying from 16% anti-
freeze to 65% antifreeze. Percentages are based on permanent type (Ethylene Glycol) antifreeze.
Most antifreeze containers have a similar table printed on the label.
December 31/91 Revised
OM-2053
2-1
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