G3516B Maintenance Guidelines Caterpillar

Reference: This information should be used in conjunction with all normally available G3500 service literature. In addition the complete G3516B service manual is SENR2265 and the specific G3516B Operation and Maintenance Manual is SEBU7201 (available on SIS).

Problem:

Since the G3516B it is a new product, Caterpillar dealers do not have any experience to be able to accurately calculated expected service costs.

Solution:

This document provides preliminary information to assist Caterpillar dealers' calculation of maintenance cost for the new G3516B. This information is provided as a comparison to a typical G3500 natural gas engine operating at 1500 rpm in a power generation application at TA Luft NOx emissions. This is also intended to assist dealers' calculation of service costs until sufficient local experience is acquired. All information provided is based on information available at the date of this document. This information should be considered as approximate and in NO way should it be considered a guarantee.

The G3516B design is based on the proven G3500 design. Therefore most of the basic core hardware is either identical or very similar and can be expected to provide the same service life as that which has come to be expected from the G3500. This includes the crankshaft, camshafts, bearings, cylinder heads, pistons, liners, rings, pumps, gears, heat exchangers and transducers. However the following equipment should be considered closely:

* Turbochargers: The G3516B is equipped with ABB turbochargers (turbo p/n 169-7439, cartridge p/n 177-4166). Purchased new, these are much more expensive then the previous turbochargers typically used. In addition Caterpillar does not yet offer remanufactured components as an alternative. Today Caterpillar directs its dealers and customers to work directly with the local ABB service shops to maintain the turbochargers at the lowest cost. Please refer to July 1999 Engine News article for a complete list of ABB service center locations. When calculating the G3516B maintenance costs it is highly recommended that this issue be reviewed to ensure it is accounted for.

For example the following is a rough comparison of new vs. previous costs: new turbo: +3.5 times, new cartridge: +3.5 times, cartridge overhauled by ABB vs. previous reman cartridge +1.35 times. Also note that to-date we do NOT have any evidence that the service life will be any different. Also, since there are no reman cartridges stocked there will be more down time when the ABB service shop is required to overhaul the turbo. If the added down time is not acceptable then turbo or cartridge parts will need to be stocked by the dealership which will add more cost.

* Spark Plugs: The G3516B operates at higher peak cylinder pressures and therefore the standard J-gap spark plug (194-8518) life is reduced. In general terms, it can be expected that the plug life will be approximately 1,000 hours. This would result in approximately a 3 times increase in spark plug cost when compared to today's G3500. Caterpillar is currently reviewing the use of a "Multitorch" spark plug (p/n 199-9012) to achieve better life. Test thus far result in plug life reaching approximately 3,000 hours. This plug has the added benefit that it is "maintenance-free" and does not require the time normally used to remove, clean, gap and re-install. However, pricing for the "Multitorch" is approximately 2 times today's J-gap plug. As an approximation, it is believed that when you account for the increased life, reduced labor time and the higher plug cost you can expect use of the "Multitorch" will result in a 1.5 times increase in spark plug costs when compared to today's G3500.

* Air / Fuel Control Valve: The G3516B uses a Woodward "Tecjet" fuel control valve (p/n 169-6572) to maintain the correct air to fuel ratio. Woodward recommends that this component be returned to their factory at each engine top end to be cleaned, checked and recalibrated. So far there is very little experience to give proper guidance. However some comments from the field have reported that the cost at the top end check can range from almost zero to the full cost of a new control valve. It should be noted that the life of the Tecjet is highly related to the fuel gas being consumed. Corrosive components and water will greatly reduce the life. It should also be noted that the service manual recommends the Tecjet inlet screens should be checked and cleaned every 4,000 hours, which will add labor cost and down time.

* Oxygen Sensor: In conjunction with the Tecjet the G3516B uses an exhaust oxygen sensor (p/n: 196-5391) to provide the feedback required to maintain the correct air / fuel ratio. The Operation and Maintenance Manual (SEBU7201) recommends that the sensor be calibrated every 2,000 hours. This requires that the sensor be removed, calibrated and re-installed. It is estimated that this will require approximately 1 hour in total to complete. Based on the particular operating conditions the calibration procedure may need to be done more often. In addition the sensor has a finite life. Today our experience is limited. However we know that water condensation from start / stop operation can have a detrimental effect. Today we believe that 1 year (8,000 hours) is a good approximation for the life of the sensor.

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