Regal 53 SC Owner's Manual page 221

The belt system has two separate belts. The primary belt
is an 8 rib design and drives the engine coolant pump and
alternator.
The secondary belt is a 4 rib design used to drive the
seawater pump. Both belts provide extra fl exibility over
standard belts and do not require a tensioning.
The 8 rib design commonly referred to as a "serpentine"
belt and is used to drive the various front engine-mount-
ed accessories. When replacing belts, sketch the routing
of the belt around the various pulleys, etc.
CAUTION
!
TO AVOID POSSIBLE ENGINE MALFUNCTION
DO NOT OPERATE THE ENGINE WITHOUT A
THERMOSTAT SINCE THE COOLING SYSTEM
WILL NOT FUNCTION PROPERLY.
Cooling System Flow
Refer to the fl ow diagram on the next page for referencing
purposes. Through the water/coolant inlet connection,
engine coolant is drawn into an integral water pump cav-
ity machined into the block. The cylinder block-mount-
ed-water pump is belt driven and pressurizes the coolant
before fl owing into the cylinder block water jacket. The
coolant fi rst fl ows around the lubrication oil cooler plates
and enters the water jacket cavity around the cylinders.
Coolant fl ows around the cylinders, but not between the
inner cylinder bores. From the cylinder block water jack-
et, the coolant fl ow continues through holes around and
between each cylinder in the cylinder block combustion
deck to the cylinder head.
From the cylinder block, the coolant fl ows into the cylin-
der head through orifi ces in the cylinder head gasket. The
orifi ces in the cylinder head gasket control the coolant
fl ow from the cylinder block to the cylinder head.
Coolant fl ow continues around the valve guide and injec-
tor areas before continuing to the exhaust side of the
cylinder head.
Before the engine reaches thermostat-opening tempera-
ture, a bypass port is opened to allow engine coolant to
fl ow back to the inlet of the water pump. Until the ther-
mostat opens, engine coolant is continuously recirculated
through the engine only. Once the engine reaches the
thermostat-opening temperature, the thermostat opens,
allows the coolant to fl ow to the heat exchanger. This
action also closes the bypass passage to the water pump.
Finally, from a port in the cylinder block near the en-
gine rear, coolant is supplied from the cylinder block to
the turbine housing of the turbocharger. Coolant fl ows
through the turbine housing into the exhaust manifold.
Coolant returns to the water pump inlet from the port at
the front of the exhaust manifold.
Antifreeze Notes
Cummins recommends the use of fully formulated anti-
freeze/coolant meeting their strict standards. Many an-
tifreeze footprints do not meet the Cummins specifi ca-
tions regarding low-silicate levels.
Cummins Inc. recommends using a product called Fleet-
guard® Compleat ES™. It is available in both glycol
forms (ethylene and propylene). Do not substitute.
Cummins Inc. recommends using either a 50/50 mixture
of good quality water and fully formulated antifreeze, or
fully formulated coolant when fi lling the marine engine
cooling system.
Good quality water is important for cooling system per-
formance. Excessive levels of magnesium and calcium
contribute to scaling problems, and large amounts of sul-
fates and chlorides cause cooling system corrosion.
Fully formulated antifreeze must be mixed with good
quality water at a 50/50 ratio (40 to 60 percent working
range) A 50/50 mixture of antifreeze and water provides
a -36ºC (33ºF) freezing point and a 108ºC (226ºF) boiling
point which is fi ne for North American locations. The
actual lowest freezing point of ethylene glycol antifreeze
is at 68%. Using higher concentrations of antifreeze will
raise the freezing point of the solution and increase the
possibility of a silica gel problem.
32
Chapter 5