140604004F
Service Bulletin Details
Public Details for: 140604004F
This informational bulletin explains the normal noises an engine may make when the ambient temperature outside is cold or the vehicle has sat for a few hours.
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Bulletin No.: Service Bulletin Date: 14-06-04-004F March, 2020 INFORMATION Subject: Various Engine Noises During Cold Start and Warm Engine Operation Models: 2015-2020 Cadillac Escalade, Escalade ESV 2016-2019 Cadillac CTS 2016-2020 Chevrolet Camaro 2014-2019 Chevrolet Corvette 2014-2018 Chevrolet Silverado 1500 2019 Chevrolet Silverado 1500 (New Model - 12th VIN Digit = 7) 2019 Chevrolet Silverado 1500 (New Model) 2020 Chevrolet Silverado 1500 2019-2020 Chevrolet Silverado 2500/3500 2019 Chevrolet Silverado 1500 LD 2015-2020 Chevrolet Suburban, Tahoe 2014-2018 GMC Sierra 1500, Denali Models 2019 GMC Sierra 1500 (New Model) 2020 GMC Sierra 1500 2019-2020 GMC Sierra 2500/3500 2019 GMC Sierra 1500 Limited 2015-2020 GMC Yukon, Yukon XL Equipped with 4.3L Engine (RPOs LV1, LV3), 5.3L Engine (RPOs L82, L83, L84) or 6.2L Engine (RPOs L86, L87, LT1, LT4, LT5) Attention: This bulletin also applies to any of the above models that may be Export from North America vehicles. This bulletin has been revised to add the 2020 Model Year to certain vehicles. Please discard Corporate Bulletin Number 14-06-04-004E. Information For Why New Engine Technologies Are Generating Noises The latest generation of full size trucks and utilities incorporate a new generation of technologies not previously seen in full size truck and utility applications. As a result these engines generate noises during cold start and during warm operation that owners of previous generation multiport fuel injection (MFI) vehicles may not be familiar with. Direct Injection (DI) / High Pressure Fuel Pump / Fuel Injectors The new Small Block Generation 5 engine family incorporates a new fuel system technology known as Direct Injection (DI). With DI, fuel is injected directly into the cylinder using a high pressure fuel system. DI provides many benefits in improving engine efficiency. Copyright 2020 General Motors LLC. All Rights Reserved. In particular, DI improves power, torque, and most importantly fuel efficiency. This technology is included as standard equipment on all Generation 5 engines in the Small Block engine family, which are the 4.3L V6, 5.3L V8 and the 6.2L V8. The high pressure fuel system does have unique operating characteristics, in particular the noise emanating from the high pressure fuel pump can result in a subtle ticking noise that is apparent when the vehicle is idling. The sound is more evident when outside around the vehicle, when the hood is open or the vehicle is operated in a drive-through. The sound may be more noticeable during a cold start, but lessens once the engine is warm. A slightly higher pitched clicking sound is the fuel injectors pulsing ON and OFF under the high fuel pressures. These sounds are a normal characteristics of the DI high pressure fuel system. Page 2 March, 2020 Another operating characteristic is a slightly longer crank time when the engine is started. The increased crank time is the result of the time required to build high pressure in the fuel system before the engine starts. Oil Pump Cold Start Rrrrp or Rasp The oil pump design has changed from a gerotor gear type pump to a two-stage vane type pump for fuel economy reasons. At temperatures at or below 0°C (32°F), or when the engine has been sitting for a few hours, it is possible to have air enter the pump through normal oil drain back. Upon startup, the owner may hear a short “Rrrrp” or “Rasp” coming from the front of the engine. It is most often heard during a remote start. There is nothing wrong with the oil pump or oil system. No repairs should be attempted for this condition. Bulletin No.: 14-06-04-004F 6.2L Engine – Dry Sump Oil System Moan The 6.2L engine dry sump oil system may generate a moan noise that may be heard inside the vehicle at idle and/or low engine rpm operation for approximately the first two minutes following a cold start. The noise cannot be heard from the outside of the vehicle. This noise may be more noticeable on the passenger side of the vehicle and has been described as similar to the sound of running water. The dry sump oil system is hard mounted to the body of the vehicle, and at cold start, the oil moving through the system can transfer the noise to the body. This is a normal dry sump oil system operating characteristic and no repairs should be attempted. GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information. WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION