QOTD #61: Does idling hurt your car’s engine?

During my time as a driver manager with a fleet of 40 vehicles, I have noticed that some of our vans have developed catalytic converter problems. The most recent was a 2012 Dodge Grand Caravan (with 123k miles) which developed a check engine light with a P0420 code. The local mechanic told me it was the bank one catalytic converter needing to be replaced. This expensive repair caused me to wonder why the unit went bad.

The company I work for transports railroad crew members from one place to another. However, there are times when the crew is not ready to go for up to three hours. As you can imagine, if it is hot, the driver will keep the van running with the AC on. Now that colder weather has arrived, our drivers keep the van running for the heat. While I don’t have a problem with our drivers being comfortable, I am wondering if the idling of their vehicles is causing problems to develop inside the engine or catalytic converter.

Search the internet and you will find forums arguing about this:

“Not true. 90% of all wear is done at start up. Once an engine is running it’s best to leave it running. Letting it idle will not harm a thing. Not back then and not today. As long as the engine has oil pressure you’re not hurting a thing. Sorry but dad was wrong.” 1

“The main problem with extended idling was the wasted fuel, fouled spark plugs, and carboned up combustion chambers from the carburetor delivered fuel system and lesser ignitions systems of the era. … But, the company my mom worked for at the time in the mid-1960’s used a fleet of Corvairs, including the van version, and without any particular problems for all of the extended idling that the delivery units were subjected to.” 2

So… who is right? And how about with newer, fuel-injected engines today? Does idling cause your vehicle’s engine to foul spark plugs, wear out quicker, and mess up your catalytic converter? Instead of relying on the forums, I decided to visit the Car Talk website to find the answer:

These days, with fuel injection and computer engine management, cars and trucks can idle until they run out of gas without doing any extra damage to the engine (assuming the cooling system is working properly). Idling does add wear and tear to the engine –anytime the engine is running, you’re decreasing the useful life of the oil and slowly wearing out parts. But it’s no more harmful than driving. 3

What do you think? Is Car Talk right about this?

Head Gasket Sealer?

Backyard Mechanic

Just today, someone suggested that the Fiero’s overheating problem is probably the head gasket. If that is the case, there are only two options if I wish to keep the car. First, I could shell out $600 to have the head gasket replaced. Second, I could try adding a liquid sealer to the cooling system in hopes of stopping the leak. But do these sealers actually work? One Youtube mechanic says that he has had 80% success with a product called K&W Engine Block Sealer. Here are his thoughts:

Note how he ends his video. Sealing the head gasket leak is only part of the solution. The other part is finding out what made the engine overheat and eventually rupture the head gasket. He suggests that common problems include a clogged radiator (which flushing will not fix) or a non-working radiator fan. What he says makes sense and would certainly be less expensive than the other option.

1984 Pontiac Fiero: overheats at stop lights

Backyard Mechanic

My 1984 Pontiac Fiero overheated this summer and wouldn’t restart. The diagnosis at the time was that it needed a head gasket. After towing it home, it sat in the driveway until the battery went dead. Then in an attempt to either fix or sell it, I had it towed to a mechanic who got it running again. The car doesn’t overheat … very often. So, it would seem that the problem is not the head gasket but something else. The thermostat has been replaced already so that is probably not the problem. I assume that it is either the water pump or a plugged radiator.


Apparently, other people have had similar problems with the 2.5L Iron Duke four-cylinder engine. The first Google listing for overheating Fiero sent me to an online tractor forum. Go figure that one out. The suggestions were anywhere from ignorant to helpful with many others in between. I include the link below for your perusal.


2003 Land Rover Freelander : Thermostat Removal

Backyard Mechanic

If you are a backyard mechanic and want to know how to change the thermostat on a 2002-05 Land Rover Freelander, this 42 minute video will be very helpful. After skimming through the instructions, I think I would rather do the job on a 2003 Land Rover Discovery II. In fact, after you watch this video, you may trade in your Freelander for a Discovery II. Or you may be wise to take your vehicle to a mechanic after watching this video. However, if you are handy with tools, have lots of time, and like a challenge, this will be fun for you. Enjoy!

2000 Mercedes-Benz ML320 stuck in Park

Backyard Mechanic

The owner of a 2002 Mercedes-Benz ML320 asked for help with his SUV on an the MBWorld Forum. Without warning, his vehicle stopped allowing him to shift out of Park. Ever had that happen to you? This is how he explained the problem:

I need your help. My gearbox is stuck in PARK…..also BAS/ESP light was on. Had the ML320 towed to a shop….and left it there. Any ideas what’s causing it to stay in PARK? This might be a protective mechanism like Limp Mode imo.

My first instinct was that some vehicles have a shift-lock release button that allows you to circumvent this problem. I could not find such a device in the 2002 model currently in our inventory. So, there must be a difference solution to this owner’s problem.

shift-lockWhat year is your model? If it is 2002 or older, my bet is the brake pedal switch. That does not mean there could not be other causes but the brake pedal switch is often the cause. You have to depress the brake pedal in order to shift out of park. With a bad pedal switch, the system cannot tell if the pedal is depressed so you cannot shift out of park. Also the bad pedal switch will also cause the warning lights for BAS/EPS, etc.

You can shift it into gear by sticking a pen into the opening on the shifter. See pic. Your shifter may look slightly different but the opening is there for all shifters.

So, there you have it. Not only can you get it out of park, you also know one of the primary causes of the problem. If you would like to read more of the conversation and see the pictures, click on the link below: