Fluid noise
Thread Starter
2nd Gear
Joined: Sep 2017
Posts: 2
Likes: 1
From: Scottsdale, AZ
Fluid noise
I have a 2017 GS with low miles. As I'm driving I hear fluids running/gushing intermittently through the system/dash. Does the cooling system need to be bleed or purged?
Safety Car
Joined: Dec 2012
Posts: 3,821
Likes: 1,844
From: St. Louis Metro East IL
You are likely hearing normal noises. See the following TSB:
Ron
Engine, Fuel System - Various Noises During Engine Operation
# 14-06-04-004B: Various Engine Noises During Cold Start and Warm Engine Operation - (Jul 8, 2014)
Subject: Various Engine Noises During Cold Start and Warm Engine Operation
Models: 2015 Cadillac Escalade, Escalade ESV
2014 Chevrolet Corvette
2014-2015 Chevrolet Silverado 1500
2015 Chevrolet Suburban, Tahoe
2014-2015 GMC Sierra 1500, Denali Models
2015 GMC Yukon, Yukon XL
Equipped with 4.3L - RPO LV3, 5.3L - RPO L83, 6.2L RPO L86 or
6.2L - RPO LT1
This Bulletin has been revised to add the Model Year 2015 Escalade and Escalade ESV and add a Section for: 6.2L Engine - RPO LT1 Dry Sump Oil System Moan. Please discard Corporate Bulletin Number 14-06-04-004A.
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. 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 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.
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 speed vane type pump for fuel economy reasons. At temperatures of 32°F (0°C) or colder, when the engine has been sitting for a few hours it is possible to have air enter the pump through normal oil drainback. 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.
6.2L Engine - RPO LT1 Dry Sump Oil System Moan
The 6.2L engine - RPO LT1 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.
Ron
Engine, Fuel System - Various Noises During Engine Operation
# 14-06-04-004B: Various Engine Noises During Cold Start and Warm Engine Operation - (Jul 8, 2014)
Subject: Various Engine Noises During Cold Start and Warm Engine Operation
Models: 2015 Cadillac Escalade, Escalade ESV
2014 Chevrolet Corvette
2014-2015 Chevrolet Silverado 1500
2015 Chevrolet Suburban, Tahoe
2014-2015 GMC Sierra 1500, Denali Models
2015 GMC Yukon, Yukon XL
Equipped with 4.3L - RPO LV3, 5.3L - RPO L83, 6.2L RPO L86 or
6.2L - RPO LT1
This Bulletin has been revised to add the Model Year 2015 Escalade and Escalade ESV and add a Section for: 6.2L Engine - RPO LT1 Dry Sump Oil System Moan. Please discard Corporate Bulletin Number 14-06-04-004A.
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. 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 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.
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 speed vane type pump for fuel economy reasons. At temperatures of 32°F (0°C) or colder, when the engine has been sitting for a few hours it is possible to have air enter the pump through normal oil drainback. 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.
6.2L Engine - RPO LT1 Dry Sump Oil System Moan
The 6.2L engine - RPO LT1 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.
