"Dr. Gizmo"
By Phil Arendt
Cold
Start Rattling Sound Raises Concern
Question
1
Recently,
I purchased a 2009 Toyota Matrix with an automatic transmission and 1.8-liter
4-cylinder engine. It has 78,000 miles
and is in great condition. The trouble
is a rattling sound in the engine. When
I first start in the morning there is a brief rattling noise. I don’t hear the rattling during subsequent
starts later in the day unless the car has been parked for an extended
period.
My
dad listened to the sound. He thinks
it’s coming from the front of the engine.
I’m concerned something major is about to happen. What do you think? C.J., email
Answer
1
Congratulations
on your recent purchase. I’m sorry to
hear there is a noise concern. Your dad
might be correct. The rattling sound
might be from the timing chain. It could
be related to an issue with a tensioning device or camshaft gears.
A
few years ago Toyota issued a technical service bulletin regarding a rattling
sound upon starts. The bulletin might
pertain to your vehicle. Ask your
favorite repair shop to diagnose the cause of the sound. For them to hear the noise consider leaving
the vehicle overnight so a technician can hear the rattling during the initial
start when the engine is stone cold in the morning. If the noise is the subject of the technical
service bulletin a camshaft gear or gears need replacement.
Many
Causes For No Heat
Question
2
There
is no heat in my 2005 Pontiac Grand Prix with a 3.8-liter engine. I replaced the thermostat but this did not
solve the problem. What else should I
look for? J.B.J., email
Answer
2
You
need heat. Unfortunately, there is much
more to check. It’s possible the water
pump is not functioning as designed.
Perhaps the heater core is clogged with scale. Perhaps the system needs a flush to restore
coolant flow through the system. Maybe
the heater core needs replacement due to scale buildup. Perhaps the actuator doors in the ducts in
the dash are not functioning as designed.
It’s possible the dash control head has failed and needs replacement. Maybe air is trapped in the system and the
coolant level is low. Perhaps the
recently, installed thermostat is defective.
Maybe the cooling system fans are not functioning as designed.
If
you are an experienced do-it-yourselfer and have the proper tools you might be
able to cure this issue. If not, it’s
time to send the car to your favorite shop.
New
Fuel Pump Fails Twice
Question
3
The
check engine light in my 2005 Volvo XC70 turned on and the engine stalled. The vehicle was towed to a shop where it
started but the check engine light was on.
A technician did tests and found a code for fuel pressure problems. He replaced the fuel pump.
The
next day the same thing happened. I was
stranded. My shop had the car towed
back. The new pump they installed had
failed. They ordered another but my
Volvo stalled again after this work.
My
shop says this pump is defective too.
What are the odds of this happening twice or is there something else
wrong? N.T.B., email
Answer
3
It’s
unlikely but possible. Their diagnosis
probably is correct. The pump is failing
to deliver the volume of fuel the engine needs.
However, if your shop is installing aftermarket parts they might
consider procuring an original equipment fuel pump from a dealership. This might be a lasting cure as sometimes
aftermarket parts don’t perform as expected.
Engine
Stalls Due To Low Voltage
Question
4
Sometimes
my 2000 Dodge Ram 3500 with a 10-cylinder engine idles rough, backfires in the
exhaust, surges and sometimes stalls.
When this happens the check engine light is not on but I notice that the
battery gauge reads all the way to the low side. If the engine stalls it starts with no
problem and runs normally. This might
happen three or four times in a week of many trips or it might not happen at
all for a month.
I
went to an auto supply store to have the computer codes read. No codes were found. I also went to a repair shop but the truck
ran fine for them during 100 miles of test drives. They scanned the computer and found no
problems. They also checked some wiring
but everything seems alright. They said
I should bring it to them when the vehicle is acting up.
The
truck has 123,000 miles. Other than
normal wear items I have not replaced any parts. The truck is in good shape for a work
truck. Do you have any suggestions? D.D., email
Answer
4
It’s
time to find a new Ram. All kidding
aside your vehicle has many more miles of service.
Curiosity
raised by the voltage gauge brings suspicion upon the charging circuit. It shows an under voltage condition. This might be caused by an issue in the
engine control module, the charging circuit including the alternator, a failing
battery and the wiring in between the alternator and engine control
module.
Your
shop checked wiring but found no issues.
If the wiring they checked was in the charging circuit it must be in
good shape. If this is true, the next
time you bring the vehicle to they might consider an issue in the engine module,
alternator or battery as these parts can cause an under voltage condition that
can cause the symptoms you describe.
Lean
Mixture Or Mechanical Condition Causes Engine Ping Sound
Question
5
There
is a rattling sound coming from the engine in my 2005 Cadillac SRX. It has 125,000 miles. I hear the sound when I accelerate. At a stop or cruising I don’t hear it.
I
went to a repair shop where they scanned the engine computer but found no
trouble codes. A mechanic said the
engine is making a ping noise. He said
the trouble might be the gasoline. He
suggested running two tanks of premium gas.
He thought that might cure the issue but the engine continues to ping.
What’s
next? R.D.F., email
Answer
5
The
next step is more testing. Ping sounds
might be caused by too lean a fuel mixture.
It’s the ratio of fuel and air and not the quality or octane of the
gasoline. Your shop will need to
determine if this is an issue or if there is a mechanical condition such as an
excessively worn timing chain that causes the condition. What needs repair depends on technician
findings
Excessive
Wear Causes Rattle Sound
Question
6
My
2011 Hyundai Elantra engine rattles. As
I accelerate the rattling begins when the tachometer reads about 1,100
rpm. The noise continues until the
tachometer reaches 1,600 rpm and then it fades away as the rpms go up.
I
went to a repair shop. They heard the
sound. They say it is coming from the
timing chain. It needs replacement.
My
car only has 102,000 miles. Does this
sound right to you? L.D., email
Answer
6
The
noise might be from the timing chain.
It’s a little premature for it to need replacement at this mileage but
it is possible depending upon how the vehicle has been driven, the driving
conditions and the preventive maintenance it received.
It’s
also possible the camshafts are making noise as in some instances excessive
wear of the camshaft bearings are capable of creating a rattling sound. Keep your fingers crossed the timing chain is
the culprit as this is the least expensive repair.
Thank
you for all the great questions. Dr.
Gizmo can’t wait to answer more.
Phil Arendt is a columnist,
consultant and A.S.E.-Certified Master Technician. Readers may send questions to Dr. Gizmo at
P.O. Box 548, Cary, IL. 60013 or e-mail address drgizmo@hotmail.com. More information is available at www.drgizmo.ws 12/07/2015 ® DR. GIZMO © 1989 - Present
