2012 - 2013 Camaro Cam & Lifter Issue
#PIP4138N: SES Light, Misfire, DTC P0300, And/or A Chirp,
Squeak, Squeal, Or Tick Noise - Potential Valvetrain Concern
- (Aug 5, 2013)
Subject: SES Light, Misfire, DTC P0300, And/or A Chirp,
Squeak, Squeal, Or Tick Noise - Potential Valvetrain Concern
Models: 2004-2007 Buick Rainier 2008-2009 Buick LaCrosse,
Allure (Canada Only) 2006-2013 Cadillac CTS-V 2002-2013
Cadillac Escalade 2010-2013 Chevrolet Camaro 2011-2013 Chevrolet
Caprice PPV 2002-2013 Chevrolet Avalanche 1999-2013 Chevrolet
Express, Silverado, Suburban, Tahoe 2009-2013 Chevrolet
Colorado 2003-2009 Chevrolet Trailblazer 2006-2009 Chevrolet
Impala SS 2006-2007 Chevrolet Monte Carlo SS 2003-2006 Chevrolet
SSR 2005-2013 Chevrolet Corvette 2009-2013 GMC Canyon 2003-2009
GMC Envoy 1999-2013 GMC Savana, Sierra, Yukon 2003-2010
Hummer H2 2008-2010 Hummer H3 2008-2010 Pontiac G8 2005-2006
Pontiac GTO 2005-2008 Pontiac Grand Prix GXP 2005-2009 Saab
97x with a V8 engine This PI was superseded to add the Caprice
PPV. Please discard PIP4138M.
The following diagnosis might be helpful if the vehicle
exhibits the symptom(s) described in this PI.
Condition/Concern Some customers may complain of a SES
light, engine misfire, and/or engine noise. If the SES light
is on, the technician will find a P0300-P0308 DTC with misfires
counting on a single cylinder that may or may not be felt.
This may occur consistently, or it may occur intermittently.
If a noise is verified, it will not be eliminated by canceling
fuel injectors and the noise will occur at camshaft speed
(half of crankshaft speed). The noise may be described as
a chirp, squeak, squeal, or tick noise and may increase
off of idle.
In either case, the cause of this concern may not be isolated
after following SI diagnosis. This PI is written for technicians
who experience this concern and follow SI diagnosis without
isolating the cause of this concern.
Recommendation/Instructions If SI diagnosis does not isolate
the cause of this concern, it may be the result of any of
the following:
- 1. Worn camshaft lobe and/or lifter roller
- 2. A sticking valve
- 3. Valve leakage
- 4. A broken valve spring
- 5. A collapsed AFM (Active Fuel Management) lifter
If SI diagnosis does not isolate the cause of this concern,
review the information below, determine which description
best matches the vehicle you are working on, and perform
the suggestions as necessary, starting with the easiest
ones first:
- Worn Cam Lobe and/or Lifter Roller: Generally, a worn
cam lobe on this engine family will create a consistent
chirp, squeak, squeal, or tick noise at camshaft speed
and/or a misfire with a P0300-P0308 DTC. The misfire may
or may not be felt and the misfire could occur at all
RPM or just a specific RPM, such as idle only or only
at high RPM. If a noise is present, it will not be eliminated
by cancelling fuel injectors and generally, the static
compression and cylinder leakage will be similar on all
cylinders.
The following suggestions may help determine if a worn
cam lobe and/or lifter is causing this concern:
- Use a wooden hammer handle to apply pressure to
the following locations of the rocker arms during
the noise to determine which one is making noise:
valve side, push rod side, and side of the rocker.
If the noise is changed by applying pressure to the
valve side of the rocker, this is most likely the
result of a lifter and/or cam lobe concern on that
cylinder. Sometimes this works, sometimes it does
not - it seems to depend on the amount of cam lobe
wear.
- Disconnect the coils
and injectors on one bank of the engine, run the engine
with the related valve cover removed, and back off
the related rocker arm a couple of turns and listen
for a change in the noise. If necessary, both rockers
and push rods can also be removed one cylinder at
a time with the related coil and injectors disconnected.
If the noise is eliminated and there is no problem
found with the valve spring, push rod, or rocker arm,
this is most likely the result of a worn lifter roller
and/or cam lobe.
- Measure the cam lobe
lift at the push rod side of the rocker arm. The lift
in this location will differ from the SI specification
but it should be similar as compared with other rockers
on the same bank. The misfiring/ticking cylinder should
obviously have less lift than the comparison cylinders
if this is the result of a worn lifter roller and/or
cam lobe. Another possibility of no/low lift on cylinders
1, 4, 6, or 7 on an AFM engine would be a collapsed
AFM lifter. If a collapsed AFM lifter is found, refer
to the latest version of PIP4568 for additional information.
- On engines with AFM (active
fuel management), you can command AFM on with the
scan tool, which will unlatch the lifters on cylinders
1, 4, 6, and 7 and stop opening the related valves.
If the noise is eliminated, there is a good chance
that the noise is coming from the valvetrain of cylinders
1, 4, 6, or 7. If there is no problem found with the
push rods, rockers, or valve springs, the noise is
most likely coming from a worn lifter roller and/or
cam lobe on cylinders 1, 4, 6, or 7.
- If the tests above do
not isolate the cause of this concern, it may be necessary
to visually inspect the lifter rollers and cam lobes
for obvious damage, such as flat spots, pits, grooves,
scoring, gouging, flaking, rusting, etc...It is very
easy to overlook a damaged cam lobe when inspecting
them through the lifter bores and just because the
lifter rollers are not worn, does not mean that the
related cam lobes are okay. Both pieces need to be
carefully inspected. It may help to use a bore scope
or pen light when inspecting the cam lobes through
the lifter bores. In some cases, the worn cam lobe
may not be discovered until the camshaft is physically
removed from the engine and inspected for the issues
mentioned above.
Notice: Follow SI procedures to replace the
camshaft and all lifters if a worn camshaft lobe or
lifter roller is found. Also replace the plastic lifter
guide for the lifter that had the damaged cam lobe
and/or lifter roller (For 2010 Model Year, replace
all of the plastic lifter guides). On AFM engines,
also replace the VLOM (Valve Lifter Oil Manifold)
filter screen that is under the oil pressure sensor.
- Sticking Valve: Generally,
a sticking valve on this engine family will cause an engine
misfire that may or may not be felt and it may occur consistently
or intermittently. It is unlikely that any engine noise
will be present. It may be temperature sensitive and it
may be more apparent during certain operating conditions,
such as driving up a grade, cresting a hill, or during
hard acceleration. A good indicator of a sticking valve
is if engine misfires continue to count on an aggressive
deceleration with engine braking. If the misfire occurs
consistently, a static compression test, running compression
test or cylinder leakage test may isolate the sticking
valve. However, it is unlikely that any of these tests
will isolate the sticking valve if the misfire only occurs
while driving at specific conditions.
The following suggestions may help determine if a sticking
valve is causing this concern:
Follow SI procedures to remove the valve springs and seals
from the valves of the misfiring cylinder. Before removing
the air pressure from the cylinder, tightly wrap a rubber
band or tie strap around the tip of each valve stem to
prevent the valves from dropping into the cylinder. Release
the air pressure from the cylinder and work the valve
up and down in the guide while turning the valve 360 degrees.
If any binding is felt, a stem to guide clearance concern
exists and should be repaired by following SI procedures.
Notice: Refer to the latest version of PIP4753 for
decarboning instructions.
- Valve Leakage: Generally,
valve leakage on this engine family will cause a consistent
engine misfire that may or may not be felt and is more
apparent at idle or low RPM. Normally, no engine noise
will be present and in most cases, a static compression
test or running compression test will not reveal anything
abnormal unless the leakage is very high.
Notice: If a valve sealing concern is found, it should
be repaired by following SI repair procedures.
- Broken Valve Spring: Generally,
a broken valve spring on this engine family will cause
a tick noise and/or an engine misfire. In either case,
the concern may occur consistently or intermittently.
If it is causing an engine misfire, it may or may not
be felt and it may only occur at specific operating conditions,
such as high RPM driving, etc...
Notice: If a broken valve spring is found, replace
the broken valve spring as necessary.
- Collapsed AFM Lifter (Engines
with AFM Only): Some customers may comment on an SES light,
engine misfire, and/or tick noise. This may be the result
of an AFM lifter that unlocks as soon as the engine is
started or one that is mechanically collapsed/stuck.
Notice: If either of these AFM lifter concerns is
suspected, please refer to the latest version of PIP4568
for additional information.
Warranty Information For vehicles repaired under warranty,
please use the appropriate warranty labor operation based
on the actual cause and repair.
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.
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