Section 7. Cooling System - Kohler LH630-775 Service Manual

WARNING: Explosive release of fluids from pressurized cooling system can cause serious burns!
When it is necessary to open cooling system at radiator cap, shut off engine and remove filler cap only when cool enough to
touch with bare hands. Slowly loosen cap to first stop to relieve pressure before removing completely.
This section covers the operation and servicing of the
liquid cooling system.
Cooling System Components
The cooling system consists of the following
components:
• Radiator with removable screen
•
Hoses
•
Coolant Pump and Belt
•
Thermostat
•
Intake Manifold with Thermostat Housing
•
Radiator Cap
•
Cooling Fan, Belt, and Drive Pulleys
•
Overflow Reservoir
•
Crankcase and Heads with Integral Cooling
Passages
Figure 7-1. Cooling System Components (Air
Cleaner Removed For Clarity).
Section 7
Cooling System
Operation
The engine coolant is pumped through the cooling
system by a pump, belt-driven off the camshaft. The
coolant coming out of the pump is divided, and moves
simultaneously through separate circuits within each
head and the corresponding sides of the crankcase. As
the coolant moves through these passages, it absorbs
heat from the engine parts. After traveling through
the engine, the coolant from the two separate circuits
merges and moves through the intake manifold to the
lower side of the thermostat. During warm-up, the
thermostat is closed, preventing circulation through
the radiator. The coolant circulates through the
engine only and is returned to the pump via the
bypass hose. When engine heat brings the coolant up
to a temperature of 79.4°C (175°F), the thermostat will
begin to open, allowing coolant to circulate through
the upper hose to the radiator. The thermostat is
completely open at 90.5°C (195°F) allowing full
coolant flow through the radiator, where it is cooled.
After getting "cooled" in the radiator, the coolant is
drawn into the pump through the lower radiator
hose and circulation starts all over again. A cooling
fan, driven off the flywheel by a belt, draws ambient
air through the radiator, to maintain the cooling
process.
Coolant Recommendations
Use equal parts of ethylene glycol (antifreeze) and
water only. Distilled or deionized water is
recommended, especially in areas where the water
contains a high mineral content. Propylene glycol
based antifreeze is not recommended.
This mixture will provide protection from -37°C
(-34°F) to 108°C (226°F). For protection and use
outside the indicated temperature limits, follow the
antifreeze manufacturer's instructions on the
container, but do not exceed 70% antifreeze.
Section 7
Cooling System
7.1
7