Excessive Engine Temperature; Insufficient Engine Temperature - Mercury D4.2L Manual

Excessive Engine Temperature

Possible Cause
•
Seacock closed, if so equipped
•
Drive belt loose or in poor condition
•
Seawater pickups obstructed
•
Faulty thermostat
•
Coolant level low in closed cooling
section
•
Heat exchanger cores plugged with
foreign material
•
Loss of pressure in closed cooling
section
•
Closed cooling section dirty
•
Faulty seawater pickup pump
•
Seawater discharge restricted or plugged
•
Seawater inlet hose kinked (restricted)
•
Use of improperly designed hose on inlet side
of seawater pump allowing it to collapse

Insufficient Engine Temperature

Possible Cause
•
Faulty thermostats
116
•
Open.
•
Replace and/or adjust belt.
•
Remove obstruction.
•
Replace.
•
Check for cause of low coolant level and repair.
Fill system with proper coolant solution.
•
Clean seawater side of water/water
heat exchanger, and seawater strainer.
•
Check for leaks. Clean, inspect and test pres-
sure cap.
•
Clean and flush.
•
Repair.
•
Clean exhaust elbow.
•
Position hose to prevent kinking (restriction).
•
Replace hose with wire reinforced design.
•
Replace.
Remedy
Remedy