Incorrect Engine Temperature; Low Engine Oil Pressure; Battery Will Not Charge; Remote Control Operates Hard, Binds, Has Excessive Free-Play, Or Makes Unusual Sounds - Mercury 4.2 Diesel Operation & Maintenance Manual

Possible Cause
Boat overloaded or improperly distributed. Reduce load or redistribute more evenly.
Boat bottom fouled or damaged.
Electronic fuel system fault.

Incorrect Engine Temperature

Possible Cause
Water inlet or seacock closed.
Drive belt loose or in poor condition.
Seawater pickups or sea strainer obstructed.
Faulty thermostat.
Coolant level low in closed cooling section.
Heat exchanger cores plugged with foreign material.
Loss of pressure in closed cooling section.
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.
Faulty thermostats.

Low Engine Oil Pressure

Possible Cause
Faulty senders.
Insufficient oil in crankcase.
Excessive oil in crankcase (causing it to
become aerated).
Diluted or improper viscosity oil.

Battery Will Not Charge

Possible Cause
Excessive current draw from battery.
Loose or dirty electrical connections or damaged wiring.
Alternator drive belt loose or in poor condition.
Unacceptable battery condition.
Remote Control Operates Hard, Binds, Has Excessive Free‑play, or Makes Unusual Sounds
Possible Cause
Insufficient lubrication on shift and throttle linkage
fasteners.
Obstruction in the shift or throttle linkages.
Loose or missing shift and throttle linkages.
Shift or throttle cable kinked.
90-8M0113988 DECEMBER 2015
eng
Clean or repair as necessary.
Have electronic fuel system checked by a Mercury Diesel authorized repair facility.
Open.
Replace or adjust belt.
Remove obstruction.
Replace. See a Mercury Diesel authorized repair facility.
Check for cause of low coolant level and repair. Fill system with
proper coolant solution.
Clean heat exchanger. See a Mercury Diesel authorized repair
facility.
Check for leaks. Clean, inspect, and test pressure cap. See a
Mercury Diesel authorized repair facility.
Repair. See a Mercury Diesel authorized repair facility.
Clean exhaust elbows. See a Mercury Diesel authorized repair
facility.
Position hose to prevent kinking (restriction).
Replace hose with wire reinforced design.
Replace. See a Mercury Diesel authorized repair facility.
Have system checked by a Mercury Diesel authorized repair facility.
Check and add oil.
Check and remove required amount of oil. Check for cause of excessive oil
(improper filling).
Change oil and oil filter, using correct grade and viscosity oil. Determine cause
for dilution (excessive idling).
Turn off non‑essential accessories.
Check all associated electrical connections and wires (especially
battery cables). Clean and tighten faulty connections. Repair or
replace damaged wiring.
Replace or adjust.
Test battery.
Lubricate.
Remove the obstruction.
Check all throttle linkages. If any are loose or missing, see a Mercury
Diesel authorized repair facility immediately.
Straighten cable or have a Mercury Diesel authorized repair facility
replace cable if damaged beyond repair.
Section 6 - Troubleshooting
Remedy
Remedy
Remedy
Remedy
Remedy
Page 73