What would cause my car to act this way?
T., via email.
Dr Gizmo says...
It is great that you have a technician who is trying to save you a few bucks. Since the check engine light is not shining, it is difficult to determine a fault. When the check engine light is illuminated a computer stores clues as to what might be causing a malfunction. When the light does not shine, a technician has little evidence to use in his search for a fault.
Be this as it may, a dirty fuel filter, failing fuel pump or failing fuel pressure regulator might cause the trouble. In some instances, troubles such as you describe might be caused by a faulty solenoid on the camshaft that adjusts camshaft timing.
Ask a technician to consider these as possible causes the next time you stop by your repair shop.
Faulty Connection Causes Diesel Engine To Misfire
My 2006 Dodge Ram with a 5.9-liter diesel engine misfires and the check light is on. I took the truck to a local shop where a mechanic did some tests but he is at a loss. He says he does not know why one cylinder is misfiring. He has checked the compression and the fuel injector. Everything checks fine.
What do you suggest?
O.C., via email.
Dr Gizmo says...Perhaps the cylinder wants some quality vacation time. All kidding aside, if the injector in the cylinder that is misfiring is fine but it is not working it is likely that there is a problem in the wiring to the injector. There may be a loose or corroded connection. Perhaps a ground connection is impaired by corrosion or is loose. Maybe the powertrain control module connection has a fault.
Ask your favorite technician to look beyond the fuel injector and consider my suggestions in his search for the fault.
Blockage Or Defect Hinders HeaterThe heater in my 2000 Cadillac DeVille does not get hot. The blower works fine. Air blows normally from the dash vents, floor and defroster with each setting on the control. It just does not provide heat.
I took the car to my dealership where a mechanic ran some tests. He says that nothing is wrong, but obviously there is. Less than a year ago, my dealer replaced the heater core so I know that is not the trouble.Whats wrong?
F.S., via email.
Dr Gizmo says...
Do not rule out a problem in the heater core. Hot engine coolant must flow freely through the heater core for hot air to blow into the cabin. If something is blocking flow such as rust deposits or even silicon sealer from a previous repair, coolant will not flow through the core to heat the passenger compartment.
Tests performed by the technician probably verified that the control module, diverter door motors and other electronics are working as designed. Now he should consider a check of coolant flow. If my hunch is right, he will find blockage in the heater core or an associated part is causing this condition.
You mentioned that it has been less than a year since the heater core was replaced. If there is a defect in the heater core, the repair might be covered by a 12 month/12,000 mile warranty. If so, you might not have to shell out a penny for this repair.
Weak Ignition Spark Stalls Engine
My 1991 Dodge Dakota with a 5.7-liter engine stalled a block from my home. With the help of a few neighbors, we pushed the truck into my driveway. My truck has 146,000 miles on it. Four years ago, I had to replace the engine because a piece of metal punctured the oil pan and the engine seized.I dont know why the engine will not run. I checked the fuel pump pressure and volume. Its fine. I replaced the fuel filter, too. I checked for top dead center. The timing is right on the mark so I know the timing chain is okay. I replaced the spark plugs because they were wet even though they are three months old. The ignition sparks. I also installed a new distributor cap and rotor. I replaced the ignition wires when I replaced the spark plugs three months ago. It was running great the day before this event. What am I missing?
P.F., via email.
Dr Gizmo says...
You must be frustrated. You mentioned key clues. The spark plugs are wet and there is spark. However, this raises a question. How strong is the spark to the spark plugs? If it is weak, it will not jump the gap across the spark plugs.
There is one part you have not replaced or checked. Test the ignition coil. Its possible for it to deliver a shot of electricity that is not strong enough to fire the cylinders. Replacement might end all of your woes.
Light No Longer Shines In Radio
Hello Dr. Gizmo. The lights inside the radio in my 2002 Pontiac Bonneville have slowly failed. Now all the lights are out and my radio is dark.
Years ago, I replaced the bulbs in a radio. Can I replace the bulbs inside this radio?
Dr Gizmo says...
It has been at least a couple of decades since radios had replaceable bulbs. It would next to impossible for you to replace the lights in your newer solid-state radio without the proper tools and equipment.
To illuminate your radio consider sending it to a repair shop, replacing it with an aftermarket unit or consider purchasing a used original equipment radio from an auto recycler.
Suspicion Raised Over Diagnosis
My 1999 Oldsmobile Cutlass with a 3.1-liter V-6 engine is at a repair shop. The car quit while driving on the highway. The state police suggested that I tow the car to a repair shop near the highway. I have never been to the shop before. Its about 25 miles from my home. The shop manager seems nice and the shop appears very nice, clean and modern.
The car has been there for three days. Today the shop manager called to tell me that the engine has bent valves. He said that he has not disassembled the engine. He wants my permission to remove the cylinder heads. I spoke with a mechanic at my local shop near my home about the trouble. He said he has never heard of such a problem in a car like mine.
Is the shop that is working on my car trying to rip me off?
Dr Gizmo says...
I understand your concern. I have been in the auto business for more years than I care to admit. I learned a long time ago that nothing is impossible. This is true in your case. Some engines are prone to bend valves. The engine in your car is not known for having such a problem but under the right conditions, valves can bend in any engine.
Call the repair shop manager and ask him to explain why he thinks the valves are bent. If he says that the compression in a cylinder or two is zero and that air is blowing out of the engine through the intake system, he has strong evidence that valves are bent.
Be prepared for an expensive repair. It might be time to say goodbye to this car.
Thanks for all of your great questions. Dr. Gizmo cant 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 [email protected] ® DR. GIZMO © 1989-2009