3406 MARINE ENGINE Electrical System Caterpillar

Electrical System
1.1. Battery
2.2. Installing Battery
3.2. Checking Charge Rate
4.2. Checking Electrolyte Level
5.2. Cleaning Battery
6.1. Cold Weather Battery Maintenance
7.2. General Maintenance
8.2. Charging the Battery
9.2. Testing Electrolyte
10.2. Connecting Booster Batteries:
11.2. Disconnecting Booster Batteries
12.1. Glow Plugs
13.2. Testing Glow Plugs
14.2. Locating Defective Glow Plugs
15.2. Installing Glow Plugs


Installing Battery

1. Be sure the battery tray is clean and free of foreign objects.
2. Be sure terminal posts and cable clamps are clean.
3. Place the battery in the tray. Tighten the hold down clamps evenly until the battery is snug. Do not overtighten.
4. Connect the "hot" terminal first. Be sure the top of the cable terminal is pushed down even with the top of the terminal post. Tighten the clamp firmly.

------ WARNING! ------

Always connect the "hot" terminal first to minimize arcing. Otherwise injury or damage could result.

5. Connect the "grounded" terminal last. Be sure the top of the cable terminal is pushed down even with the top of the terminal post. Tighten the clamp firmly.
6. Apply a thin coating of grease over the cable clamps, terminals and hold down fasteners.

Checking Charge Rate

1. After starting the engine, the ammeter indicator should register to the right of zero, but should never be "pegged".

2. After the engine has been running, the indicator should be just to the right of zero.

If the indicator remains far to the right of zero, or remains to the left of zero with an increase of engine speed, have the electrical charging system checked.

Checking Electrolyte Level

A proper charge rate will require periodic additions of water.

1. Remove each vent cap and check the electrolyte level in each cell.
2. Add water to maintain the electrolyte level to the base of each vent well. Make-up water must be one of the following (in order of preference):
a. Distilled water.
b. Odorless drinking water.
c. Iron free fresh water.
d. Any available fresh water.

------ WARNING! ------

Never add acid or electrolyte solution.


Cleaning Battery

Over a period of time, corrosion will appear on battery terminals, and the top of the battery case will accumulate oil and dirt. To maintain battery efficiency, these accumulations must be removed.

1. Mix a weak solution of baking soda and water.
2. Apply the solution with a clean, nylon bristle brush; avoiding the holes in the vent caps.
3. Allow the baking soda to work on the terminals and battery case for a few minutes. If reaction is fast, a second application may be needed.
4. Thoroughly rinse the battery and battery tray with clean water.
5. Examine. If required, repeat procedures.
6. Inspect cable clamp condition. Replace cables if necessary.
7. Check tightness of cable clamp bolts. They must be tight.
8. Apply grease to the battery cable clamps, terminals and hold down fasteners.

Cold Weather Battery Maintenance

General Maintenance

1. After adding make-up water, charge the battery. The added water could dilute the electrolyte enough without charging to cause freezing and permanent damage to the battery.
2. Keep the batteries fully charged either by operating the charging system or by using a battery charger.
3. Keep the battery warm when not in use. In an unheated area, the heat from a lighted electric bulb is usually sufficient.


Use only a shop cord with a heavy wire guard around the light bulb.

Do not lay a lighted bulb directly on a battery case; the heat at point of contact could melt the battery case.

Do not lay cloth or flammable material in contact with a lighted bulb; charring and/or fire could result.

4. Use starting aids as instructed for starting the engine.
5. Use booster batteries as required. Connect the batteries as instructed below.
6. If a battery is not going to be used for a period of time, be sure the battery is fully charged while stored. Use a battery hydrometer to check the specific gravity of each cell, and use a battery charger to keep the battery charged. See the instructions below.

Charging the Battery

------ WARNING! ------

Never smoke near the area where batteries are being charged. Hydrogen gas is given off at each vent cap during charging. Hydrogen mixed with air is highly explosive.

1. Connect positive charger clamp to positive battery terminal.
2. Connect negative charger clamp to negative battery terminal.
3. Connect charger power cord to proper outlet.
4. Allow battery to charge slowly.


If battery is charged too rapidly, the battery will be damaged.

5. After the battery is charged, disconnect charger power cord from outlet; remove charger clamp from negative battery terminal; remove charger clamp from positive battery terminal.

Testing Electrolyte

NOTE: If the electrolyte level is too low to allow taking a hydrometer reading, add make-up water to the correct level and then charge the battery 2 to 4 hours before taking a reading.

1. Insert the hydrometer tube into a cell. Fill the hydrometer barrel while holding the hydrometer in a vertical position. The float must not drag on the wall of the barrel.

1.250 or above: fully charged battery cell; freezing point @ -60°F (-51°C)

1.225 - 1.250: half to fully charged battery cell; freezing point @ -40°F (-40°C)

1.150 - 1.225: low to half charged battery cell; freezing point @ -20°F (-29°C)

Below 1.150: dead battery cell; freezing point @ +10°F (-12°C)

1.000: water; freezing point is +32°F (0°C)

2. Read the hydrometer.

NOTE: Specific gravity ranges shown above may vary because of electrolyte temperature, battery construction or strength of electrolyte used in different climate zones.

3. Test each cell in the same manner. If there is more than .050 (50 gravity points) variation between the highest and lowest reading, the battery should be replaced.

The hydrometer reading is of most importance during cold weather. A low specific gravity reading means the battery has less available power to crank the engine, booster batteries may be required, or the battery may freeze if not charged.

Connecting Booster Batteries:

1. Remove all filler caps from all batteries before connecting jumper cables.
2. Connect red jumper cable to "hot" terminal of booster battery.
3. Connect black cable to "ground" terminal of booster battery.


Keep red and black terminals from touching each other.




4. Connect other end of red cable to "hot" terminal of engine battery.
5. Connect other end of black cable to the starter ground terminal, if equipped with a starter to ground cable.

If the starter is not grounded with a cable, attach the black cable terminal to a good ground on the engine or engine frame, at a point away from, and below the battery.

6. Start the engine using starting aids as instructed in the Operation Instructions.

Disconnecting Booster Batteries

As soon as engine starts:

1. Disconnect black jumper cable from engine.
2. Disconnect red jumper cable from engine.
3. Disconnect black cable from booster battery.
4. Disconnect red cable from booster battery.
5. Charge booster batteries to full capacity with a battery charger.

Glow Plugs

Testing Glow Plugs

1. Stop the engine.
2. Disconnect the lead harness wire from the magnetic switch.
3. Connect an ammeter of sufficient capacity between the magnetic switch terminal and the lead harness wire.
4. Push in, turn and hold the HEAT-START switch in the HEAT position.
5. The ammeter reading should equal the number of glow plugs multiplied by the amperage of each glow plug.

Calculate the amperage of each glow plug by dividing its wattage by its voltage. These values are stamped on each glow plug. The amperage should be 3.5 amperes to 7 amperes per glow plug, depending upon the engine.

A deviation from the calculated reading will indicate one or more defective glow plugs.

Locating Defective Glow Plugs

1. Push in, turn and hold the HEAT-START switch in the HEAT position. Observe the ammeter reading.
2. Pull the lead from a glow plug. Observe the ammeter reading.

NOTE: If the ammeter reading does not change, the glow plug was not drawing current when connected and can be assumed to be defective. If the ammeter reading decreases, the glow plug is working properly.

3. Release the HEAT-START switch.
4. Connect the lead to the glow plug.
5. Test each glow plug individually.

Installing Glow Plugs

1. Disconnect the lead wire at the defective glow plug.
2. Remove the defective glow plug.
3. Apply anti-seize compound to the threads of the new glow plug.
4. Install the new glow plug and tighten to a torque of 10 to 12 pound-feet (1,38 to 1,66 mkg).
5. Turn the HEAT-START switch to the HEAT position and observe the ammeter reading.
6. Release the switch.
7. Install the lead wire.
8. Turn the HEAT-START switch to the HEAT position. The reading should increase. If the reading is the same, check the glow plug wiring.
9. Disconnect the ammeter.