Argument between me & my old man


#1

My dad has a 2002 Jetta (probably irrelevant)and here’s what the dispute is about:



Occasionally I ride with him and when he parks the vehicle he shuts everything off… by everything I mean heating/cooling and radio and wiper blades if applicable.



I ask him why he does this and he says to “save the battery” and I always argue that this only makes sense for leaving the car parked overnight and then starting it stone cold the next morning. Cold start = hard on the battery, Luke warm start = No problem.



Who is correct? Thanks!


#2

I don’t think it makes any difference, any time, most all that stuff doesn’t run in the ‘engine start’ position for the key. If it does, then it makes a tiny difference. I would turn off the wipers to get them ‘parked’, and not left up on the glass.


#3

People get set in their ways,Senior’s reasoning is false and your reasoning is also false.

It is a good idea to shut the AC compressor off a few minutes before you shut the fan down.

I like my wipers parked.

I don’t like the radio comming on upon start.

My preferences have nothing to do with “saving the battery” it does not need saving,my battery has penty of reserve.


#4

It’s NOT saving battery. Makes no difference if everything is on or off…or parked over-night or just 2 minutes.

When you turn the ignition off it shuts everything off (except the lights). So there is no strain what-so-ever.

When you go to start the vehicle the next morning…by turning the key to start it will also shut everything off (except the lights) until the car is started and key is moved back to the on position.


#5

Thanks oldschool. I like my wipers parked too just out of curiosity why is it a good idea to shut off the compressor prior to shutting off the fan? Interesting.


#6

If you do not shut off the wipers, and leave the car in freezing weather, make sure you LOOSEN UP the wiper blades before starting the car. I’ve burned out a wiper motor by not shutting off the wipers.


#7

Running the blower with the compressor off tends to dry the evaporator coils,this inhibits mold build-up (you know the gym sock smell the AC sometimes puts out)there a kits called after-blow kits than run the blower for extended periods of time after engins shut down(up to 30 min that provide extra drying)


#8

Actually, I think your dad is doing the prudent thing.

It does absolutely no harm to shut everything down first, and should he try to start it with the wipers on and the blades are stuck in ice he could damage the linkage, or should he try to start it on a below-zero day with the headlights on and the battery marginal, that could make starting it more difficult.

Besides, unless someone is doing something that you believe dangerous or harmful, their protocols are really just a matter of preference…especially of it’s their car and their financial responsibility! If you’r eold enough to be having this argument, that tells me your dad has many years of driving experience from which you can learn if you’re open to doing so. My own kids, both grown adults, are finally realizing that the ol’ man wasn’t so dumb after all!


#9

It drives me nuts when I turn the ignition switch and there is lots of movement and sound. Your dad is probably the same way so be considerate, since it is his car, and do what he asks, sonny.

(The distractions detract from my car-starting experience. When I hear the starter turn over I like to revel in the fact that I am making stuff explode under the hood.)


#10

You are both wrong. He is likely wearing the switches enough to counter any savings by doing what he is doing. You are wrong because you are not just saying, “That’s a good idea dad.”


#11

Off topic - a gallon of gasoline release about the same amount of energy as 400 sticks of dynamite! So those are some powerful explosions!


#12

sometimes there is no “correct”. It is obvious from the above posts that we all do things a little differently for various reasons, some very logical and others not so…this is what makes life so much fun and reading car talk posts so interesting…rarely find absolute agreement and the discussions usually are informative.


#13

Be happy that these things seem important to worry about. When I was young, the questions were all about how to feed us next week.


#14

I would beg to differ on that first point. I too always turn everything off, even drive always with my headlights on no matter the time of day or weather (which means I constantly cycle the switch), and in over 40 years have never worn a switch out yet. Even after hundreds of thousands of miles.

Switches occasionally wear out, just because everything possible eventually happens, by those are really premature failures.


#15

When you are starting the engine NOTHING IS ON EXCEPT THE IGNITION (AND STARTER). Therefore there should be NO distractions. As has been stated already, in freezing weather, it might be wise to park the wipers.


#16

I would beg to differ on that first point. I too always turn everything off, even drive always with my headlights on no matter the time of day or weather (which means I constantly cycle the switch), and in over 40 years have never worn a switch out yet.

 And I am not even a little surprised.  My point is that neither action has any meaningful effect on the car.

#17

This is off topic, how?


#18

just out of curiosity… how much gas vapor is injected into the cylinder with each explosion? mostly just a small spray correct?


#19

how much gas vapor is injected into the cylinder with each explosion?

Here is a back-of-the-envelope approximation. Someone please correct me if I made a math error:

Assuming a 6 cylinder car that gets 30mpg and is traveling at 60 mph and the engine is turning at 2000 RPM, that means in 1/2 hour:

  • the car would have burned 1 gallon of gas,
  • the engine would have turned over 2000x30=60,000 revolutions.
  • that 60,000 revolutions times 6 cylinders = 360,000 pistons going up and down.
  • since every other stroke is a power stroke, the engine had 180,000 cylinders get fuel and fire during that 30 minutes.

To summarize the above approximation, the engine would use 1 gallon of fuel for 180,000 times fuel is injected into the cylinders. So yes, it must be a very small spray.

Please correct any errors or omissions in my approximation.


#20

Off topic because it doesn’t have much to do with turning off switches…and I think Joe got the math right. So 1 gallon = about 4 liters = 4000 ccs/ 180,000 firings = about 0.02 cc/firing…not much!