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Friday, July 20, 2012

Northwest Herald Dr. Gizmo Column Dated July 13, 2012

"Dr. Gizmo"
By Phil Arendt
 

Cure For Failed Interior Lights On Horizon  
Question 1

The interior lights in my 2002 Buick LeSabre with 39,000 miles quit working.  Two repair shops have attempted to fix the trouble.  They have replaced the battery and alternator.  After repairs the lights work for a while, but it isn’t long before they quit. 

I’m about to take the car back for more repairs.  Can you help?  B.J., Marengo, IL

Answer 1
My goodness with only 39,000 miles your car is barely broken-in.

It appears that technicians discovered a low voltage issue.  This more than likely is the reason for replacing the alternator and battery.  Now that these parts have been replaced the trouble may still be due to low voltage as a result of excessive parasitic discharge of the battery or perhaps a lack of vehicle use. 

Tests should determine if the vehicle is suffering from high parasitic discharge.  If this is the trouble a technician needs to determine the circuit that is causing the condition and find the accessory, wire or module that causes it.  Once this is determined, repair might be as simple as repositioning a pin in a plug.

If the cause of the condition is determined to be a lack of vehicle use, a technician might suggest installation of a battery maintainer which is a small device that monitors the state of the battery and charges it when needed.  The device is permanently installed in the vehicle, but you will need to plug it into household outlet when not using the vehicle and unplug it before hitting the road.

Parts Drain From Engine During Oil Change
Question 2

My 2009 Volkswagen Jetta needed an oil change.  I took the car to a quick lube for the service.  When the mechanic drained the oil he said two needle bearings fell out of the drain hole.  He gave them to me.  He said in the past other parts have drained with the oil and there did not seem to be anything wrong with those cars.   

The bearings are thin, round and are about a quarter of an inch long.  The engine runs normally and does not make any unusual sounds.

My car has 67,000 miles.  The engine is a 2.0-liter.  I have taken good care of it.  No one has ever found anything like this in the oil before.  Should I be concerned? D.C., email


Answer 2
Maybe.   Over the years when I have drained the oil from an engine bolts, nuts and even a valve system rocker arm fell from the drain and there were no problems with the engines.  While this may be the situation with your car an examination of an exploded view of the VW 2.0-liter engine shows that needle bearings such as you describe might be from a roller rocker arm in the valve system.

Even though the engine seems to run fine consider an exam of the valve system.  This is not major surgery.  A technician removes the valve cover at the top of the engine to gain a clear view of the rocker arms.  If one is falling apart, replacement is rather simple.

Engine Stalls On Tight Turns
Question 3

When making tight turns or when turning into a parking space my 2004 Chevrolet Suburban stalls.  A mechanic at a local shop performed several tests but could not find any problems.  During a test drive the vehicle stalled for him, but he was not able to determine the cause of the trouble.  He said that a problem such as this could be caused by a defective crankshaft or camshaft sensors.  He said during tests the sensors check out fine but I asked him to replace them.  The new parts did not cure the trouble.

Have you ever heard of a problem such as this?  H.K., email

Answer 3
Stranger things have happened.  After all these years I have learned anything is possible.  There may be an unusual electrical problem within steering wheel or column.  In the steering wheel and column is an electrical device that provides connections for the air bag and horn.  There also is circuitry for the turn signals, windshield wipers and ignition.  Since the engine cuts out at a specific position of the steering wheel perhaps a wire in the column just below the steering wheel makes contact with rotating parts and shorts a circuit.  The result is a dead engine. 

At this point, ask your technician to consider a visual examination and tests of the devices and wiring within the steering column. 

Tap Test Might Find Cause Of Problem
Question 4

The headlights in my 2006 Dodge Grand Caravan work when they want.  At this time of year it’s not such a big problem but once winter comes I will need them.  I can be driving along with the lights on and suddenly they shut off.  Then they might flash a few times or remain off for a few minutes and then turn back on.  If I hold the high beam light switch at the right angle I have lights so I can drive otherwise I have no headlights.  As I continue to drive the headlights might come back on and not turn off.  Once they turn on it may be a week before they act up again.    

I took the vehicle to a shop to have the trouble fixed but they were working fine for the mechanic.  He checked wiring and did some tests but found no problems. 

What’s up?  D.M., email

Answer 4
Your car is flashing oncoming motorists to alert them to police radar speed traps.  Good job!

All kidding aside, it appears that the problem is due to a loose connection.  Since a technician found no loose wires, faulty body or front control modules the trouble might be within the headlamp switch.  Tapping on the switch might find there is a loose connection in the unit.  If the tap test verifies the trouble, replacing the switch should return the lights to normal function.

Computer Points To Problem, Technician Disagrees 
Question 5

My 2001 Nissan Sentra with a 1.8-liter engine lacks power and won’t accelerate passed 2500 rpm.  The car has 140,000 miles.  I went to an auto supply to have the computer checked for codes.  The man who tested the car found a code for the mass air flow sensor.  I installed the part and wiring that came with it but the engine continued to run poorly and the check engine light turned on. 

Next, I took the car to a repair shop.  A mechanic did a number of tests.  He found the same code as the man at the auto supply store.  He installed another air sensor but the same trouble occurred.  He tested the sensor circuits and found everything normal.

He also tested the cam shaft system, checked the fuel pump, tested the exhaust system for blockage and did a test on the cylinder compression.  The engine passed all tests except compression.  He said the engine should have 165 to 185 pounds of pressure and mine has 125.  He said that this is why the check engine light is on.  The air flow sensor is not the cause.  He says at the very least the engine needs a valve job. 

If tests show that the air flow sensor is the cause of the trouble why would the engine need a valve job?  A.P., email

Answer 5
What your technician says makes sense.  Think of the engine as an air pump.  The engine sucks air in when the pistons go down.  An intake valve closes in the cylinder head to trap the air.  When the pistons go up the air is compressed to increase pressure.  An exhaust valve opens and high pressure air rushes out.

Sensors on the engine monitor just about everything the engine does so that the engine control module can adjust timing, fire the spark plugs, shift the transmission, recirculate exhaust gasses and much more.  All of this is done in fractions of second, thousands of times a second and everything has to run within design specifications.

The mass air flow sensor measures the volume and temperature of air rushing into the engine.  When the engine has a lack of pressure or compression it also does not draw as much air in.  The cause is due to leaky valves or piston rings.  When there is a lack of air rushing in the engine, the engine control module sees the information from the sensor in the form of voltage and resistance that is not within programmed software specifications.  As a result, the module turns on the check engine light and sets a trouble code that points a technician toward trouble in the mass air flow sensor and related circuitry. 

Fortunately, it is more likely than not that the cause of the trouble is due to excessively worn valves as opposed to excessively worn piston rings.  Renewing the cylinder head is much less expensive than overhauling or replacing the engine.

Fuel Injector Cleaner Is Not A Cure-All
Question 6

The 5.7-liter engine in my 2002 GMC Savana 3500 spews black smoke when I start it in the morning and it idles poor.  I replaced the spark plugs, wires, distributor cap, rotor and pcv valve.  I had a buddy clear the engine computer of codes.  After all of this work the engine did not run any better and the check engine light turned back on.  I added fuel injector cleaner to the gas, but this had no effect.

I took the truck to a repair shop where a mechanic checked the compression and a number of other tests.  He determined the trims are off and thinks the fuel injectors are the cause.  He says there are multiple misfire codes in the engine computer caused by faulty fuel injectors.

Injectors are expensive.  Wouldn’t adding more cleaner resolve the trouble?  J.L.N., email

Answer 6
Scratch adding more fuel injector cleaner off your list.  You tried it and it has not fixed the trouble.  Fuel injector cleaner does work to remove deposits that can build up but it can’t reverse wear.

Fuel injectors wear out.  Often the electronic parts falter.  At other times mechanical parts suffer from wear.  Tests should determine whether there is mechanical or electrical failure.  If indeed any electrical or mechanical fault exists, ailing injectors need replacement.

Thanks for all of your 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@drgizmo.ws.  07/09/2012 ® DR. GIZMO © 1989-2012

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