Fact or Fiction

What a great project for the guys on my favorite TV show! Thank you for sending the suggestion to them.

Since there are no explosions, gunfire or car crashes involved, TV shows won’t be interested. Turning on you headlights before attempting to start your cars does only one thing. It makes it less likely the car will start.

Todays fuel-injected, computer controlled engines will usually start if the battery has enough power to crank the engine…If the battery will not crank the engine, buy one that will…

Glad to be of help. I don’t get Mythbusters so I’d appreciate their scientific conclusions posted here if you would. Thanks

when i was a kid, my mom subscribed to this theory.

so when she started the old dodge slant six it was, lights on, wait, crank, rrrrvroom.

when my dad started the car it was like this, crank
rrrrvroom.

no discernable difference that i could tell, other than mom was satisfied with her theory.

upon reflection there is no science to back up this claim. however the same could be said for hydrogen.

After charging the battery and the weather warming up 30 degrees from -1 the van started right up. So I’ve come to the conclusion there just wasn’t enough cold cranking amps to start it at -1 degrees. So before we get another forcast for say 10 degrees I’m buying a high rated cold cranking amp battery. Thank you all for your excellent in-put.

What! No battery blanket?!

Question first. Was this Dodge 318 a new vehicle. If not, how old was it? And what rubber are you talking about?
Sorry, I don’t buy the WD-40 killing rubber for several reasons, not the least of which is the fact I’ve used it for decades on rubber with no problem.

When performing a PDI on new cars (Pre-Delivery Inspections) standard operating procedure was to go over all of the door and trunk seals with WD-40. This was done to prevent any squeaks that may occur and head off any complaints from new car owners.
Plug wires, dist. cap, etc. were also sprayed with WD-40 as it is pretty humid here and this was done to prevent the possibility of a new car absorbing moisture in the ignition system thereby causing a no-start or rough running condition.
I’ve never, ever seen a problem with door seals or ignition wires.

As to the bit about the battery, turning the lights on consumes a few amps of current including the initial surge. The amount consumed is not enough to cause a sluggish or no-start condition or even affect the starter current draw at all.
The starter motor draws a certain load depending on temperature, oil weight, engine condition, etc. and this is not affected one bit by flipping the headlights on.

Matter of fact, the CCA is almost irrelevant if the battery is good because the starter current draw is not anywhere near what the CCA of the battery is.
My opinions are simply based on quite a few decades of automotive electrical work and testing along with what I was taught in a number of service schools.
I had to sit one time and listen to a heavily accented German service instructor (VW) drone on for almost 4 hours about how an automobile battery actually works.
The Gestapo wasn’t even that cruel.

If turning the lights on will increase the cranking amps of the battery we must assume that it’s because of the current draw on the battery. Why not draw MORE current from the battery, and improve the cranking capacity even more?

It would certainly be easy to draw more current than using the lights. Just use the starter. The very act of trying to start the engine should, if your theory is correct, improve the cranking capacity of the battery. If the engine starts the first time, you could shut it off so that you can use your improved capacity to now restart the engine.

By this theory throwing a large end wrench across the battery terminals and cauaing a major short should work wonders for the battery starting capacity.

On a related note, Motor Trend published an article by an “automotive journalist” who stated that the new taillamp bulb design in the new Mustangs uses 87% less current than the old bulbs and this equates to saving 10.5 gallons of gas per year.

One Of My Fieros Was Delivered New At A Pontiac Dealer In Fairbanks And Came With A Plug-In Battery Heater. (I have the new car window paper)

Do We Have A Tech Guru Living In A Cold Climate Who Can Go Out And Do A Scientific Test? Any Volunteers?

When I get done shoveling my roof again (winter day 2, global cooling) and get caught up, I’ll try it. What do I need to do? What minimal equipment do I need?
We Have made -19F, so far last week (Autumn).

It has been a few years past, but it was reported here and, as I recall, supported by the brothers, that turning on the head lamps for a short time, and I believe allowing a minute or two rest time for the battery did result in better cranking under the conditions of the test, which was rather cold as I recall. I don’t recall which theory was suggested.

However as I also recall, it was not really enough of a difference to make it a worthwhile trick, and I would have to guess trying to start the car and having failed waiting a minute or two and trying again would do as well or better.

WD-40 is a water displacement and would be a terrible choice for cleaning a carburetor as it quickly dries to a sticky goo.

In cold weather turn on your lights before trying to start your car. It will increase the cold cranking amps and start your car easier without running down your battery. Fact or Fiction?

The theory behind this was that turning your lights on would heat up the battery just a little to increase it’s cold cranking power. I have no idea if it works. In my opinion if your battery is that far gone you should replace it anyways.

You must be kidding.

Wouldn’t hurt to charge it while sitting inside too. I do this every two months, only in the winter, on a car I drive short trips twice a week. My last battery in this car lasted over 7 years.

This is true, in fact I once had a car that would not turn over, the temp was 5 below, I did this and the engine started.

This is true if you have a somewhat healthy battery.

Did you pursue the cause of your engine’s failure to crank further? or were you satisfied with the explanation that this was a “X” Files event?

Test the theory! Yes, I say, test the theory. Use a clamp on amp meter, and the the procedure the theory specifies. Take a reading of the amperage output. On the next day, when conditions are identical, do the test without turning the headlight on. Repeat the test, on a number of days, to get the best averages.
We know that no theory believer will put it to the test, don’t we?! So, the unsubstantiated theory goes unchallenged, and continues ad infinitum…

Utter tripe IMHO but tell you what I will do.
I’ll throw my ammeter and voltmeter on my guinea pig Lincoln tomorrow and measure this every which way but loose.

Battery voltage, starter current draw, etc, etc. will all be measured “normally” and with the lights on scenario.

There is no way on God’s green Earth that turning on the lights for a few seconds is going to miraculously cause a non-cranking car to start all of a sudden.
Better go back to cable ends, ignition switches, fusible link connectors, etc to find that problem.

It’s been plenty cold here in OK and the results will be posted tomorrow.