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General Information
Preparations For Starting
Before Starting
Starting Engine
Engine Break-in and General Running
Stopping the Engine
Decompression Lever
Instrument Panel
Wiring Diagram
Preparing Engine for Storage
Preparing Engine for Spring Service
Fuel Injection Timing
Diesel Valve Timing
Adjusting Fuel Timing
Decompression Device Adjustment
Fuel System
Fuel Bleeding
Oil Filter Change
Sea Water Pump and Impeller Replacement
Model 15 Sea Water Circulation Diagram
Model 12, 18, 20, 25, 25XP, 30, 40 & 50 Water
Fresh Water Circulation Diagram

Hurth Transmission
Periodic Service Chart for Engine
Marine Engine Warranty - Limited

Engine Specifications and Images
(by engine model)



Model 15 Sea Water Circulation
Normal Range 135 to 144 F

1. Sea water enters thru sea water inlet

2. Through sea water valve when open

3. Into mixing tee to suction side of pump, located below water line

4. Out of pump by hose to inlet on side of block

5. Circulates through block into cylinder head

6. Leaves head on top front to exhaust manifold

7. Circulates through manifold to thermostat

8. Enters thermostat which remains closed during warm up, permitting a small amount 
of water to enter exhaust system for cooling and overboards.

9. As engine temperature rises the thermostat starts to open, permitting hot water to enter exhaust line. At the same time the same amount of cool sea water is drawn in by the pump to replace the discharge hot water. This is done through the mixing tee which is located below engine (or water line) to prevent air from entering the system.

10. There may be some fluctuation in engine temperature until engine stabilizes.

11. In areas of cold inlet say 50, you may notice some movement from 135 to 155 as engine R.P.M. are changed. This is less noticeable with warmer inlet water. The reason being that the colder water causes thermostat to react faster than engine temperature stabilizes.

12. It may appear at first that no water is being pumped overboard with the exhaust gases. However as long as water temperature is within operating range (135 - 155), there is a flow of water being pumped overboard which may be noticed only as a fine mist. This will continue until the thermostat directs the water flow overboard to allow for greater intake of cooler sea water.