Failures of a Jacket Water Pump on Some G3500 Engines{1350, 1361} Caterpillar

Engine:

G3520B (S/N: GET1-UP; GLF1-UP)

Generator Set:

G3516C (S/N: GSB1-UP; GZZ1-UP; TJB1-UP; TJC1-UP)

G3516E (S/N: GAS1-UP; SLY1-UP)

G3520B (S/N: CWD1-UP; GZP1-UP)

G3520C (S/N: MAD1-UP; GZJ1-UP; GZK1-UP; GZL1-UP; GZM1-UP; GZN1-UP; B9P1-UP; HAT1-UP; CWW1-UP; CWY1-UP)

G3520E (S/N: GZG1-UP; SXY1-UP)

Introduction

The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use a solution that is identified below.

Problem

Failures of the 258-8725 Water Pump Gp (Jacket Water) on the above generator set engines have been reported. The primary failure mode has been coolant leaks through the pump's weep hole due to a damaged water seal.

Damage to the water seal occurs when a seal overheats. Dry running of the pump or pump cavitation will cause overheating of the water seal.

The characteristics of the design of the pump are being evaluated. The following factors are the main contributors to dry running water pump seals and water pump cavitation:

• Application

• Installation

• Design of the cooling system

• Maintenance

• Operation

Solution

The above problem continues to be investigated. In the interim, Caterpillar recommends the following solution:

• The cooling systems must be designed to Caterpillar requirements.

• Ensure that the following proper maintenance practices are used: filling procedure for coolant, engine starting procedures, check for external restrictions and purge air from the cooling system.

Filling and Venting

While the coolant system is filled, air can be trapped. Proper filling and venting will minimize these air pockets. Refer to the Application and Installation Guide, LEBW4978, "Cooling Systems" for details about filling and venting. Also follow the guidelines for filling and venting the cooling system.

• The engine must be filled from the bottom with coolant at a rate no faster than 19 L (5 US gal) per minute. The cap must be removed from the expansion tank during filling of the cooling system.

• The vent line must be routed with a continuous upward slope from the highest point of the engine's cooling system to the bottom of the expansion tank.

For a system with a volume that is greater than 284 L (75 US gal), the vent lines must be a minimum diameter of 9 mm (3/8 inch).

For a system with a volume that is greater than 568 L (150 US gal), the vent lines must be a minimum diameter of 13 mm (1/2 inch).

Engine Start-Up

Perform the following procedures in order to ensure that the air is purged after a cooling system has been filled:

• Do not accelerate the engine directly to high idle speed.

• Run the engine at low idle speed for approximately ten minutes.

• During the initial ten minutes of running, monitor the expansion tank and maintain the coolant level above the minimum mark.

Design of the Cooling System

The design of the cooling system must be evaluated if the commissioning procedure for the cooling system has not been completed successfully.

All systems must be designed as shown in the guidelines in Application and Installation Guide, LEBW4978, "Cooling Systems".

Refer to Engine Data Sheet, LEKQ8288, "Sizing Customer Furnished Cooling Systems" for sizing information for the cooling system.

For guidelines for the field test of the cooling system, refer to Engine Data Sheet, LEKQ7235, "Cooling System Field Test". The field test of the cooling system must be completed during the engine commissioning. This must be considered when pump failures occur.

Pump failures that are associated with poor design of the cooling system are typically caused by the following:

• Excess system restriction

• The lack of a shunt line

• Low system pressure after shutdowns

• Undersized expansion tanks

Expansion Tank

In order to absorb an after-boil that may occur during a hot shutdown, the expansion tank must be sized properly.

An expansion tank in a jacket water system that is a standard temperature must be a minimum of 15 percent of total volume of the system.

An expansion tank in a jacket water system that is high temperature that is greater than 100 °C (212 °F) must be a minimum of 25 percent of total volume of the system.

Pressure Cap

In order to help prevent an after-boil that may occur during a hot shutdown, the proper pressure cap must be installed. The pressure of the system must be 27.5 to 34.4 kPa (4 to 5 psi) above the pressure that forms steam.

A pressure cap for a standard engine is typically 27.5 to 48.2 kPa (4 to 7 psi).

A pressure cap for an engine that is in a landfill application is typically 130.9 to 151.6 kPa (19 to 22 psi).

Information that Must be Reported to the Dealer Solution Network (DSN) in the Event of a Failure of a 258-8725 Water Pump Gp (Jacket Water)

In the event of a pump failure have your technical communicator contact the DSN as soon as possible. Supply the following information to the DSN:

• Description of the problem

• Provide a data log from Caterpillar Electronic Technician (ET) at no load and rated load from a cold start with the following parameters: jacket water pressure, jacket water coolant temperature, engine load, engine speed, oil temperature and oil pressure

• Describe the initial commissioning procedure.

• Describe the procedure for engine start-up after cooling system maintenance is performed.