Kohler 3.5CFZ, 4CZ, 5CFZ, 6.5CZ Cooling Systems- Closed/Heat Exchanger, Filling and Checking

Cooling Systems— Closed/Heat Exchanger

In a closed cooling system, the seawater does not circulate through the engine but circulates through separate chambers within the heat exchanger to cool the engine coolant. The seawater is then mixed with engine exhaust and ejected out the exhaust outlet. The coolant is circulated through cooling passages to cool the engine. All models make use of a coolant thermostat and a coolant recovery tank. The coolant capacity of the engine with heat exchanger is 0.72 U.S. qts. (0.68 L) for all models. A solution of 50% ethylene glycol and 50% clean, softened water is recommended to inhibit rust/corrosion. A coolant solution of 50% ethylene glycol will provide freezing protection to --34°F (--37°C) and overheating protection to 265°F (129°C). A coolant solution with less than 50% ethylene glycol may not provide adequate freezing and overheating protection. A coolant solution with more than 50% ethylene glycol can cause damage to engine and components. Do not use alcohol or methanol antifreeze or mix them with the coolant.

Filling and Checking

WARNING

Hot coolant and steam.

Can cause severe injury or death.

Before removing pressure cap stop generator, allow to cool and loosen pressure cap to relieve pressure.

Hot coolant can cause severe injury or death. Allow engine to cool and release pressure from cooling system before opening pressure cap. To release pressure, cover the pressure cap with a thick cloth then turn it slowly counterclockwise to the first stop. After pressure has been completely released and the engine has cooled, remove cap. If generator set is equipped with a coolant recovery tank, check coolant level at tank.

NOTE

ENGINE DAMAGE! Failure to bleed air from cooling system may cause overheating and subsequent damage to engine.

NOTE

Special attention should be given when checking for proper coolant level. After the coolant has been drained, it normally requires some time before complete refill of the engine water jacket takes place.

Before filling the cooling system, verify that all hose clamps are tight. Loosen air-bleed screw located on top of the engine to allow trapped air to escape. See Figure 3-14. Place a rag around the screw to prevent coolant spillage onto the block. Remove pressure cap located on the top of the engine (see Figure 3-15) and fill with the recommended coolant until level is just below overflow tube opening. Tighten air-bleed screw when coolant, free of air bubbles, starts to flow. Replace pressure cap. Start generator set and allow to run for about 20--30 seconds. STOP generator set and recheck coolant level by removing pressure cap. Repeat procedure, as necessary, until coolant can no longer be added.

A coolant overflow bottle is provided. Fill bottle to just below the MAX mark. See Figure 3-16. Maintain proper coolant level in coolant overflow bottle. The MIN mark indicates full when cold and the MAX mark indicates full when hot. Coolant level should always be between these marks. The coolant level can be checked using the overflow bottle markings, but it is recommended to periodically remove the coolant pressure cap and check coolant level.

3-12 Scheduled Maintenance TP-5695 12/93