OMC Evinrude Johnson Tube Water

The water tube in an OMC Evinrude or Johnson outboard motor is a crucial part of the cooling system. It acts as the conduit that carries water from the water pump( located in the lower unit) up to the powerhead (engine block), where it circulates to cool the engine.

Function:

1. Water intake: Water is drawn into the system through intakes in the lower unit.
2. Water Pump: The water pump (driven by the driveshaft) pressures the water into the water tube.
3. Water Tube: The water tube carries the pressurized water upward to the engine block
4. Powerhead Cooling: Water circulates through passages in the engine block to dissipate heat.
5. Thermostat and Pressure Relief Valve: The thermostat and pressure relief valve regulate water flow and pressure for optimal cooling
6. Water outlet: Water eventually exits the cooling system, often via a pee hole or overboard indicator
   

Common Issues:

Clogs: Debris or dirt can clog the water intake or the water tube, preventing proper cooling.

Bent or Damaged Tube: The water tube can be bent or deformed, potentially during lower unit installation, leading to reduced water flow or complete blockage.

Failed Grommets/Seals: The rubber grommets or seals that connect the water tube to the water pump and engine block can deteriorate, causing leaks or loss of pressure.

Replacement:

Access: Replacing the water tube typically involves removing the powerhead to access the upper end of the tube.

Special Considerations: For some models, it might be necessary to pull the powerhead to replace collapsed or melted water tube grommets.

Alignment: Proper alignment of the water tube with the water pump outlet and upper grommet during reinstallation is crucial. 

Note: If you are experiencing cooling system issues with your OMC Evinrude or Johnson outboard, it's essential to troubleshoot the problem thoroughly to identify the cause. This may involve checking the water intakes, inspecting the water pump, and examining the water tube and its connections. If you are not comfortable performing these repairs yourself, consider seeking assistance from a qualified marine mechanic