0378973 JOHNSON GEARCASE ASSY.,Upper

Checking Coolant Level
With the engine stopped:1. Slowly turn the filler cap to the first stop and release pressure.
Be careful. If the engine is warm-steam may spray outward under high pressure.
2. Push the cap down; turn until the cap is released.3. Maintain level to base of fill pipe. The coolant requires expansion space as it is heated.
PROPER COOLANT LEVEL4. Make-up coolant should be one of the following, in the order of preference: a. Permanent anti-freeze and water solution.b. Drinkable water and rust inhibitor solution.c. Drinkable water.d. Any available water.(a) Must be used if engine is to be shut down in below freezing weather without draining the coolant. (b) Can only be used when the coolant temperature is above freezing, or if the coolant will be immediately drained after shut down during below freezing temperatures.(c) or (d) Should only be used as a "temporary fix". As soon as possible, return the system to either (a) or (b).Checking Water Temperature Gauge Reading
The water temperature gauge should normally register in the NORMAL range when operating. However, with some systems, as long as the coolant does not boil the cooling system is functioning properly. 1. If the water temperature gauge continually registers near-or in the "HOT" range-without boiling, have the system checked to determine if the cooling system is functioning properly.2. Frequently check the water temperature gauge while operating. Be sure to note any deviation from the normal reading.3. Whenever the reading changes, investigate the cause and have necessary repairs made.Draining Radiator Or Expansion Tank
Whenever it is necessary to drain the cooling system for repairs:1. Shut the engine off.2. Slowly turn the pressure cap to the first stop and release pressure.
Be careful. If the engine is warm-steam may spray outward under high pressure.
3. Push the cap down and turn until the cap is released.4. Open the drain valve on the radiator, if so equipped.
COOLANT DRAINDraining Complete Cooling System
1. Remove the engine block drain cover; rear left side.2. Remove the water pump drain plug.
COOLANT DRAINS3. Remove the oil cooler bonnet drain plug.
COOLANT DRAIN4. Remove the water shield drain plugs if equipped with a water cooled manifold.5. Remove aftercooler drain plugs if so equipped.6. Allow the coolant to drain.7. Install all drain covers and plugs.8. Close the radiator drain valve.Flushing Cooling System
To clean the cooling system, any good commercial radiator cleaning solution can be used. Follow the instructions included with the cleaner.The cooling system can be cleaned using oxalic acid and sodium carbonate as follows: 1. Fill the cooling system with a solution consisting of two pounds of oxalic acid or sodium bisulphate (NaHSO4) with every 10 gallons of water (mix 0,24 kg with every 10 liters of water).2. Start the engine and operate at operating temperatures for 1/2 to 1 hour.3. Stop the engine and drain the cooling system.4. Flush the system with clean water until the draining water is clear.5. Install all drain plugs.6. Fill with a solution consisting of 1/2 pound of sodium carbonate crystals (Na2CO3, 10 H2O) with every 10 gallons of water (mix 0,06 kg with every 10 liters of water).7. Start and run the engine for 10 minutes.8. Stop the engine and drain the cooling system.9. Flush the cooling system with clean water.10. Install all drain plugs.Filling Cooling System
1. Add either rust inhibitor or permanent type anti-freeze. Do not add both.2. Fill to correct level with water which is free as possible from scale forming minerals.3. Open the raw water valve.4. Start and run engine for 10 minutes.5. Remove the radiator cap and check the coolant level.6. Add coolant, if needed, until coolant is to the bottom of the filler tube.7. Install the radiator or expansion tank cap.Fan Belts And Drive
1. Check belt wear.2. Apply a 25 pound (10 kg) force, perpendicular to the belt, midway between the driver and driven pulley and measure the belt deflection.3. Proper belt deflection is 9/16 to 13/16" (14 to 20 mm). Adjust the belt tension as required.4. If one belt in a set requires replacement, always install a new matched set of belts-never replace just the worn belt. If only the worn belt is replaced, the new belt will be carrying all of the load-as it will not be stretched as much as the older belts-and all of the belts will fail in rapid succession.
MEASURING BELT DEFLECTIONAdjusting Fan Belts
1. Loosen the four nuts holding the fan plate to the engine block.2. Loosen locknut. Turn the adjusting screw until belt is adjusted properly.3. Tighten the four nuts and locknut.4. Check the belt adjustment.
ADJUSTING FAN BELT TENSIONLubricating Fan Drive
Lubricate the fan drive bearing with grease; 1 or 2 strokes, 1 fitting.
FAN DRIVE BEARINGRaw Water
Salt water has a highly corrosive reaction with metal by a chemical action called "electrolysis". To prevent this chemical action taking place, with parts used in the raw water system, zinc plugs are placed in the raw water piping. Zinc is a relatively soft metal which reacts quite readily with the salt water. Thus, by the deterioration of the zinc, the raw water system parts are protected from corrosion.The zinc rods must be inspected regularly and be replaced as they become deteriorated. The zinc rod plugs are painted red for easy identification.Inspecting Zinc Rods
1. Move the governor control lever to the shut-off position.2. Remove and inspect all of the zinc plugs. They are painted red for easy identification. Depending upon the engine, their location may be in the oil cooler heat exchanger bonnet, raw water heat exchanger bonnet, aftercooler lines, raw water pump, or in the raw water lines.3. Tap the zinc rods lightly with a hammer.
ZINC PLUGS4. Inspect the rods. If a rod has deteriorated, or flakes apart when tapped, install a new zinc rod.
INSPECTING ZINC RODInstalling New Zinc Rod
1. Unscrew or drill the existing rod from the plug base.2. Install a new rod in the plug base.
INSTALLING NEW ZINC ROD3. Install the plug.