Bulletin No.: PIP5331C
Date: 18-Apr-2016

Subject:

Ticking, Tap, or Rattle Noise From Engine

Models:

2013 - 2016 Buick Enclave, LaCrosse
2013 - 2015 Cadillac ATS, CTS
2013 - 2016 Cadillac SRX, XTS
2013 - 2015 Chevrolet Camaro
2015 - 2016 Chevrolet Colorado
2013 - 2016 Chevrolet Captiva Sport, Equinox, Impala, Traverse
2013 - 2016 GMC Acadia, Terrain
2015 - 2016 GMC Canyon
Equipped With a HFV6 Gen 1 Engine

This PI was superseded to update Recommendation/Instructions. Please discard PIP5331B.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern
Customers may bring their vehicle into the dealership for a rattle, tick, or knock type noise.
Note: If there are any drivability concerns they should be addressed prior to the following diagnostic progression.
Note: Please take a sound file or video with sound of the noise prior to dis-assembly.
This may be needed when contacting TAC or to be sent to engineering.
This could be all the time, only under load, or intermittent depending on the severity of the noise.
You may find this noise hard to isolate to one area in the engine.
After you have recorded a sound file of the noise try to isolated the noise to a general area of the engine.
At that point following the steps in this PI in ORDER may help pinpoint the concern.

Recommendation/Instructions
1.

Perform injector diagnosis to ensure there are no leaking injectors causing a noise due to excessive fuel in 1 cylinder.
a) Perform GDS2 or AFIT test on injectors to isolate a leaking injector.
b) Replace any out of specification injectors
c) Reevaluate the noise.

2.

Remove the intake manifold and visually inspect for excessive carbon on the intake valve stems and top of the valve causing noise
a) If carbon is present then follow the latest version of PIP5029 to clean the valves or replace heads as needed.
b) Reevaluate the noise concern.

3.

Remove the cam cover of the affected bank (both if needed) to inspect for soft or spongy SHLAS (stationary hydraulic lash adjusters) (Lifters).
a) Push down on the rocker end at the SHLA to test for soft or spongy. (right side exhaust are most common but could be any)
SEE PICTURE

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b) If soft or spongy SHLAS are found, carefully remove the affected head and inspect the oil passage below the head gasket for debris.

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c) If debris is found, inspect the camshaft caps for wear or discoloration due to lack of oil.
d) If wear or discoloration is found then replace the cylinder head assembly with camshafts.
e) If there is no wear or discoloration, clean the oil passages and replace the head gasket.
f) Change the oil and filter.
g) Reevaluate the noise concern.
4.

Raise the vehicle while running or with an assistant inside

a) With chassis ears or a stethoscope, listen to the right and left side of the engine.
b) Once the noise is isolated or if unable to isolate, remove the piston and rod assemblies from the affected bank(s) to inspect for either; a loose rod bushing in
the rod, or a loose wrist pin in the bushing. We have seen both.
c) There should be no metal through the oil for this condition.
d) If this is found a piston and rod assembly will repair this noise.
For all of the above engine replacement is not necessary. Please perform the repairs for these conditions.
Note: If metal is found in the oil or throughout the system refer to the latest version of PIP5216
Once all of the above inspections and / or diagnostics are completed, If nothing is found to be the cause for the noise, engine replacement MAY be necessary.

Warranty Information
For Vehicles Repaired Under Warranty Use Appropriate Labor Operation For Process Performed.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the
remaining steps do not need to be performed.
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,

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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

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