Engine Overheats (Cooling System)
Cause
Special Information
IMPORTANT: The first step is to verify if the en-
gine is actually overheating or the temperature
gauge or sender is faulty.
IMPORTANT: Best way to test gauge or sender is
to replace them.
Loose or broken drive belt
Seawater shutoff valve partially or fully closed
(if equipped)
Clogged or improperly installed sea strainer
Loose hose connections between seawater
pickup and seawater pump inlet (models with
belt driven seawater pump only)
Pump will suck air. Pump may fail to prime or will
force air bubbles into cooling system.
Seawater inlet hose kinked or collapsed
Seawater pickup clogged
Obstruction will be in front of seawater pickup,
causing air bubbles to be forced into cooling
system
Obstruction on boat bottom causing water
turbulence
Defective thermostat
Exhaust elbow water outlet holes plugged
Insufficient seawater pump operation
Worn pump impeller
Obstruction in cooling system such as casting
flash, sand, rust, salt, etc.
Refer to water flow diagram for engine type
being serviced
Engine circulating pump defective
Also refer to “Engine Overheats (Mechanical)”
IMPORTANT: In addition to previous checks,
make the following checks if engine is equipped
with closed cooling.
Low coolant level
Antifreeze should be mixed 50/50 or maximum
Antifreeze not mixed properly
Heat exchanger cores plugged
60/40
(60% antifreeze, 40% water)
Water hoses reversed at the water distribution
block
Refer to water flow diagram in Section 6
Index
90-823224--2 796
TROUBLESHOOTING - 1C-27
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1993, 1994, 1995, 1996, 1997 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
(4 votes, average: 4.5 out of 5)
Marine readers have rated 1993 1997 Mercury-MerCruiser GM V8 454 CID 7.4L and 502 CID 8.2L Marine Engines Service Manual Number 16 4.5 out of 5.0 based on 4 product reviews. Hugely helpful service manual! Perfect. Thank you!
Manuals are all Important for Technician
This book is invaluable if you do your own repairs. Great book.
Could not find a copy until a search brought me here.
Excellent print.
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