Causes of High Pump Bearing Temperature and Effective Cooling Solutions

In the daily operation and maintenance of industrial pumps, bearings serve as critical supporting components. They are responsible for supporting the rotor, reducing friction, and ensuring the alignment between the impeller and pump casing. The operating condition of bearings directly determines the stability, service life, and continuity of pump operation.

Abnormally high bearing temperature is one of the most common failures in centrifugal pumps, plunger pumps, and gear pumps. Typically, a temperature exceeding 70°C for rolling bearings or 65°C for sliding bearings is considered a warning threshold. Continuous overheating can lead to bearing annealing, raceway spalling, cage deformation, shaft wear, and even severe failures such as shaft seizure or pump damage.

Therefore, understanding the root causes of high bearing temperature and applying effective cooling measures is essential for equipment maintenance personnel.

1. Root Causes of High Pump Bearing Temperature

1.1 Lubrication System Failures (Primary Cause)

Lubrication is the key factor in ensuring proper bearing operation. Any lubrication failure can quickly generate excessive heat.

Insufficient lubrication: Lack of oil film causes direct metal-to-metal contact and rapid heat generation

Excessive lubrication: Leads to churning resistance and shear heat (often overlooked)

Degraded or contaminated lubricant: Oxidation, water ingress, or impurities reduce viscosity and lubrication performance

Incorrect lubricant type: Mismatch between viscosity and operating conditions (speed, load, temperature)

Blocked lubrication lines: Insufficient oil supply due to clogged filters or pipelines

1.2 Bearing Quality and Installation Issues

Improper bearing selection or use of low-quality/used bearings

Excessive or insufficient interference fit

Improper installation methods (e.g., hammering instead of proper tools)

Incorrect preload or clearance adjustment

These issues increase internal friction and load, leading to overheating.

1.3 Cooling System Malfunctions

Blocked cooling channels due to scale or debris

Insufficient cooling water flow or pressure

High cooling water temperature

Leakage causing water contamination in lubricant

Failure of the cooling system leads to heat accumulation and rising temperatures.

1.4 External Load and Operational Problems

Misalignment between pump and motor shafts

Cavitation or impeller blockage

Excessive flow or overload operation

Rotor imbalance causing vibration

Excessive axial force due to balancing device failure

Poor ventilation or high ambient temperature

1.5 Seal Failure and Medium Contamination

Leakage from mechanical seals or pump body may allow process fluid to enter the bearing housing, contaminating lubricant and increasing temperature, especially in chemical or high-temperature applications.

2. Effective Cooling and Troubleshooting Measures

2.1 Emergency Cooling Actions

Reduce pump load, flow rate, or speed

Increase cooling water flow and pressure

Use forced air cooling (fans)

Stop the pump immediately if temperature continues rising

2.2 Lubrication System Optimization

Maintain correct oil level (typically 1/2–2/3 of housing volume)

Replace degraded or contaminated oil

Clean oil circuits and filters

Use proper lubricant based on operating conditions

Ensure stable oil supply in forced lubrication systems

2.3 Cooling System Restoration

Clean and descale cooling pipelines

Repair or replace damaged cooling components

Ensure adequate water pressure and flow

Install additional cooling devices if necessary

2.4 Bearing Replacement and Proper Installation

Replace damaged bearings with original-quality products

Use proper tools (heating or hydraulic installation)

Adjust bearing clearance and preload correctly

Align pump and motor shafts accurately

2.5 Operational Optimization

Remove debris from impeller and pump chamber

Eliminate cavitation conditions

Perform rotor dynamic balancing

Repair sealing systems

Improve ventilation and reduce ambient temperature

2.6 Preventive Maintenance Strategy

Implement regular temperature monitoring (manual or online systems)

Follow lubrication best practices (right person, place, time, quantity, and quality)

Standardize installation and maintenance procedures

Regularly inspect cooling systems, alignment, and vibration

High pump bearing temperature is usually caused by a combination of factors including lubrication, installation, cooling, load, and environment. Temporary cooling measures alone are not sufficient. A systematic approach focusing on root cause analysis and corrective actions is essential.

By ensuring proper lubrication, efficient cooling, correct installation, and optimized operation, bearings can maintain stable, low-temperature performance, extending pump lifespan and ensuring safe, continuous industrial operation.