The useful life and warranty periods for off-road equipment in California for engines rated at 37 kilowatts (kW) and greater have not been updated since the Tier 1 rule phased in from 1996 to 2000; for engines rated below 37 kW, not since the Tier 2 and Tier 3 rules phased in from 2000 to 2008. The California Air Resources Board (CARB) staff is seeking information regarding useful life and warranty to evaluate whether amendments to those requirements are necessary after two decades of technology advancement.

Cal Poly researchers called 55 service providers across the state of California to collect information regarding useful life of engines, repair of emission-related components, and warranty information associated with various off-road agricultural & construction equipment. The responses below reflect 40 completed interviews. The data was collected via telephone interview with the service manager of each company. The interviews took place during the post-harvest, pre-plant season of November 2022 through early May 2023. Most interviews took from 20 – 40 minutes to complete.

Participants were asked about the types of equipment and most common range of horsepower (HP) engines they saw in their shop. The equipment each service provider dealt with mostly depended on the type of agriculture surrounding their area. Tree and vineyard crops typically use smaller HP tractors (less than 100), while large row crop operations in the southern San Joaquin Valley more commonly use 200 – 500 HP equipment. Construction equipment providers reported the largest horsepower, in the 400 – 600 HP range, though that varied depending on whether they were dealing with bulldozers, graders, or smaller equipment such as skid steers. Of the 40 service managers interviewed, 32 represented agricultural shops, six were exclusively construction and two shops worked on both agricultural and construction equipment, but tilted more heavily toward agriculture. The following data was collected for each participating service provider.

  • Types of equipment and horsepower range
  • Percentage of rebuild vs. replacement engine work
  • Issues with replacement engines
  • Customer decision factors for rebuilding vs. replacement
  • Rebuild information for off-road engines
  • Hourly Rate in Shop/Field
  • Useful life & repair costs for various engine and emissions components: o Selective Catalytic Reduction
  • Turbochargers
  • Diesel Oxidation Catalysts (DOC)
  • Exhaust Gas Recirculation (EGR) Valve and EGR Coolers
  • Oxides of nitrogen (NOx) Sensors
  • Diesel Particulate Filters (DPF)
  • Fuel Injectors
  • Diesel Exhaust Fluid (DEF) Doser/Header
  • DEF Quality Sensors
  • Engine Control Unit (ECU)
  • Exhaust Manifold

The power range of equipment most commonly serviced by each provider is noted in Table 1. Though most providers reported working on a wide variety of machinery, most had an engine size range that was more common, as noted below. The construction dealers were the most variable, while the agriculture equipment dealers typically had more common ranges of sizes based on the type of agriculture in the area.



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