Mercury 8.1S Horizon, Product Applications Manual

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Cooling System
Page 7A-12 90-863758060 AUGUST 2006
• Accessible for observing level and servicing coolant.
12837
d
e
f
b
a
12838
c
c
d
e
a - Recovery bottle
b - Mounting bracket
c - Screw and flat washer (2 each
provided)
d - Plastic tubing
e - Tubing clamp
f - Heat exchanger fill neck
Water Heaters
!
CAUTION
Avoid overheating damage. Mercury MerCruiser is not responsible for engine damage
caused by improper heater installation.
Mercury MerCruiser engines are designed to allow connection of a water heater. Ensure
that the water heater complies with the following:
Description Specification
Engine operating temperature range 71–79° C (160–175° F)
Maximum pressure at the heater connections 172 kPa (25 psi)
IMPORTANT: Engine may not maintain proper temperature if heater supply and return
hoses are too large.
• Maximum ID of heater supply and return hose: 16 mm (5/8 in.).
• Make heater connections only at locations specified.
• Do not reposition the temperature senders or switches for the purpose of making the
connections. Senders and switches may not operate properly if repositioned.
• Heater should be mounted so that heater element is below connections on engine to
avoid air locking. On models with closed cooling systems trapped air will eventually
work its way back into the cooling system and could cause overheating.
• The system should be arranged so that the heater hoses slope progressively upward
(toward the engine) to minimize the need for air venting. Avoid U-bends in the hoses.
• Hoses should be kept as short as possible with a minimum number of bends.
• Hoses should be properly supported to prevent chafing and interference with moving
parts on engine.
• Drain plugs should be fitted at the lowest point in the system for draining.