Peeing

The absence of water discharge or “peeing” from your Nissan 50 four-stroke outboard is a warning sign that requires immediate attention. This tell-tale water stream serves as a visual indicator that your engine’s cooling system is functioning properly. When this stream is weak or absent, it signals potential cooling problems that could lead to overheating and significant engine damage. The following comprehensive analysis explores the most common causes of this issue and provides practical solutions that both DIY boat owners and professional mechanics employ to restore proper cooling function.

Understanding Outboard Motor Cooling Systems

Outboard motors utilize a raw water cooling system that draws water from the body of water the boat is operating in. This system consists of several key components working together to maintain optimal engine temperature. Water enters through intake ports on the lower unit, is pumped upward by the impeller in the water pump, circulates through the engine block to absorb heat, and finally exits through the tell-tale discharge port.

The “peeing” or tell-tale stream is not merely an aesthetic feature but serves as a critical visual indicator that water is properly flowing through your engine’s cooling system. When functioning correctly, this stream should be consistent and strong, especially when the engine is at higher RPMs.

Common Causes of Poor Water Discharge

1. Clogged Water Intake

One of the most frequent reasons for an outboard motor not “peeing” properly is a blockage in the water intake ports. Located on the sides of the lower unit just above the propeller, these ports can easily become obstructed by:

• Aquatic weeds and vegetation
• Plastic bags or other floating debris
• Silt, sand, or mud buildup
• Small stones or shells

These obstructions restrict water flow at the very beginning of the cooling circuit, resulting in insufficient water volume reaching the tell-tale outlet. This issue is particularly common when operating in shallow, weedy, or debris-filled waters.

2. Impeller Issues

The water pump impeller is a rubber component with flexible vanes that rotates to draw water through the cooling system. Being made of rubber, this part naturally deteriorates over time and is considered a regular maintenance item. Impeller problems that can affect water discharge include:

• Worn or brittle rubber vanes that have lost their flexibility
• Broken vanes due to running the engine without water or after striking debris
• Impeller that has slipped off its drive shaft
• Improperly installed impeller (wrong orientation)

Many outboard technicians recommend replacing the water pump impeller every season or at least every other season as preventative maintenance, even if it appears to be in good condition.

3. Clogged Discharge Tube

The tell-tale discharge tube itself can become clogged with debris, mineral deposits, or fragments from a deteriorating impeller. This presents a situation where water is properly circulating through the engine but cannot exit through the indicator port.

A simple test to determine if this is your issue involves removing the tube and attempting to blow air through it. If airflow is restricted, the tube is likely clogged.

4. Internal Cooling Water Blockage

Sometimes the issue lies deeper within the engine’s cooling passages. Internal blockages can be caused by:

• Fragments of a deteriorating impeller that have entered the cooling system
• Mineral deposits from saltwater use
• Small debris that passed through the water pump
• Corrosion buildup in older engines

These blockages are more challenging to diagnose and address without specialized knowledge and tools, as they may be located in narrow cooling passages within the powerhead.

5. Thermostat Problems

Outboard motors utilize thermostats to regulate engine temperature by controlling coolant flow. A stuck or faulty thermostat can restrict water flow through the cooling system, affecting the tell-tale discharge. While your engine might still operate without overheating (depending on water temperature and operating conditions), the reduced flow can manifest as a weak or inconsistent tell-tale stream.

Step-by-Step Diagnostic and Repair Approaches

Initial Diagnostic Steps

1. Visual Inspection: With the engine off, examine the water intake ports on the lower unit for any visible obstructions or blockages.
2. Tell-Tale Tube Check: Remove the tell-tale tube and attempt to blow air through it to check for blockages.
3. Water Intake Test: With the boat in water (or using flush muffs), run the engine briefly while covering and uncovering the water intakes to see if this affects water discharge, which would indicate a partial blockage elsewhere in the system.

Fixing a Clogged Water Intake

1. Turn off the engine and raise the lower unit out of the water.
2. Manually remove any visible debris from the water intake ports.
3. For stubborn blockages, use a small wire or pick to carefully clear the openings.
4. In some cases, briefly running the engine in reverse can help dislodge debris (only attempt in sufficient water depth).

Addressing Impeller Issues

1. Remove the lower unit: This typically involves removing mounting bolts and disconnecting the shift linkage. Remember to mark the position of the trim tab before removal for proper reinstallation.
2. Access the water pump assembly: Remove the water pump housing, which is typically located just above the gearcase.
3. Inspect the impeller: Look for signs of damage like:
   • Cracked or missing vanes
   • Hardened rubber
   • Flat spots or wear marks
4. Replace the impeller and related components:
   • Apply waterproof grease to the new impeller
   • Ensure proper orientation (the impeller must be installed to rotate in the correct direction)
   • Consider replacing the entire pump assembly rather than just the impeller
   • Use new gaskets and apply appropriate sealant as needed
5. Reassemble the lower unit: Carefully reinstall all components, ensuring proper alignment and torque on all fasteners.

Clearing a Clogged Discharge Tube

1. Locate the tell-tale tube connection point on the engine.
2. Disconnect the tube from the engine.
3. Use a small piece of wire, a pipe cleaner, or compressed air to clear any blockages.
4. If blockage persists, consider replacing the tube entirely.

Addressing Internal Cooling Blockages

For internal blockages, which are more complex to resolve, several approaches can be taken:

1. Flushing the system: Connect a garden hose to the engine’s flush port (if equipped) or use flush muffs over the water intakes, and run fresh water through the system for several minutes to dislodge minor blockages.
2. Chemical descaling: For mineral deposits, commercially available descaling solutions can be circulated through the cooling system following manufacturer instructions.
3. Pressure testing: Some mechanics use pressure testing equipment to identify and sometimes clear blockages in the cooling system.
4. Creative approaches: As mentioned in one source, there are “creative ways to dislodge an internal cooling water blockage without having to disassemble the cylinder head,” though these may require specialized knowledge.

Professional Mechanic’s Approach

When faced with a Nissan 50 four-stroke outboard not “peeing,” a professional mechanic would typically follow this diagnostic and repair sequence:

1. Initial assessment: The mechanic would first verify the complaint by running the engine with proper water supply and observing the tell-tale discharge.
2. Basic troubleshooting: Check for obvious issues like clogged water intakes and discharge tube blockages.
3. Water pump inspection: If basic troubleshooting doesn’t resolve the issue, the mechanic would likely drop the lower unit to inspect the water pump and impeller.
4. Comprehensive cooling system check: This might include:
   • Testing water pressure at various points in the cooling system
   • Inspecting thermostats for proper operation
   • Checking for internal blockages using specialized tools
   • Examining water passages for corrosion or debris
5. Component replacement: Based on findings, the mechanic would replace any faulty components, typically including:
   • Water pump impeller (and often the entire pump assembly)
   • Water pump housing if worn
   • Gaskets and seals associated with the cooling system
   • Thermostats if faulty
6. System flushing: After repairs, the cooling system would be thoroughly flushed to remove any remaining debris.
7. Operational testing: The engine would be run for an extended period to ensure proper cooling function and adequate tell-tale discharge under various operating conditions.

Conclusion

The lack of water discharge from your Nissan 50 four-stroke outboard’s tell-tale port is a symptom that should not be ignored, as it indicates potential cooling system issues that could lead to overheating and engine damage. While the problem can often be resolved through relatively simple measures like clearing blockages or replacing the water pump impeller, more complex internal cooling system issues may require professional attention.

Regular preventative maintenance—including annual or biennial water pump impeller replacement, careful operation in debris-free waters, and proper engine flushing after each use (especially in saltwater)—can significantly reduce the likelihood of experiencing cooling system failures. By understanding these common causes and solutions, boat owners can better maintain their outboard motors and potentially avoid costly repairs resulting from overheating damage.