Saturday, June 4, 2016

Listening to Your Car

Being in touch with your car means listening to it.

A lot of folks have a hard time with cars, mostly because they don't understand how they work.   And since they don't pay attention to their cars, they take small problems and turn them into big ones, or worse yet, get stuck somewhere.

Listening to your car will help you understand whether it is working properly.   And a lot of noises cars make tell you whether something is working right or not.   Not all noises are bad things, either.  In fact, it is often the absence of noise that tells you something has gone wrong.

1.  Fuel Pump:   In many cars, when you turn the ignition key to the "on" position, the electronic fuel pump turns on for a brief moment.   It stays on for just a second, until the fuel system is pressurized, and then shuts off.  Modern cars use fuel injection which requires pressurized fuel from an electronic pump, usually located under the car or in the gas tank itself.

Listen for this whine of the fuel pump the next time you start your car.  Turn the key to the on position and see if you can hear it.   If you don't, don't worry - so long as the car starts.   Some newer cars have quieter fuel pumps, and of course, these push-button start cars don't allow you to pause with the key in the "on" position.

If your car does make this noise, and one day decides not to start, check to see whether the fuel pump is turning on.   It could be something as simple as a blown fuse or a crash sensor.   Many cars have a sensor that detects whether there has been a crash and then shuts off the fuel pump to prevent everyone from being sprayed with flaming gasoline.   Usually there is a reset button in the trunk or hatch to reset this sensor, if it is set off by accident.  Consult your owner's manual and see if you have one.

By the way, running a car out of gas is really bad for the fuel pump (in most cases).   In some cars, the fuel pump is in the tank itself (making replacement a pain in the butt) and the gasoline in the tank actually cools the pump.  Running the tank to empty will shorten the life of the fuel pump and leave you stranded somewhere someday.

2.  Fan Roar:  Most cars today have multiple cooling fans.  Some have electric fans only, others have an engine-driven fan supplemented by an electronic cooling fan that kicks in when the engine gets hotter or if the A/C is turned on.

The engine driven fan usually has a thermostatically controlled clutch ("fan clutch") that engages the fan when additional cooling is necessary.  When you first start the car, you may hear the engine-driven fan "roar" for a few moments before the clutch disengages.   Make a note of this.   If you stop hearing this roar on cold starts, maybe your fan clutch is bad.

Similarly, if your auxiliary cooling fan goes South, the A/C may not work well.  When you turn the A/C on, you should hear this fan go on (or if you can see it when you open the hood, it should start turning).   If not, you need to see your A/C specialist.

By the way, fan roar is normal when it is hot out.   Many folks "freak out" when they are driving their car or truck, under load, on a hot day and the engine temperature goes up.   The fan clutch engages and suddenly you hear this "roar" from under the hood as the fan kicks in.  This is normal.   A lot of folks go so far as to seek out a mechanic, convinced the car is breaking down.

Of course, engine-driven fans are becoming a thing of the past, as more and more cars have electric fans only (particularly front-wheel drive cars).   But in trucks and some SUVs, as well as some sports cars, engine-driven fans are still the norm, and fan roar is still normal - on startup, and when the vehicle is under load on a hot day.

3.  Compressor Noise:   Similarly, when you turn the A/C on, an electronic clutch on the A/C compressor is engaged to start the A/C system.   You should hear this and also note a minor change in engine speed.   If your A/C suddenly stops working and you don't hear the usual noise (and see if the A/C pulley moving with the hood up) then chances are you have a bad A/C clutch, or the system is so low on charge, that the low pressure sensor has shut down the A/C system.

4.  Belt Noise:  Almost all modern cars have serpentine belts, eliminating the fussy v-belts of yore, that required constant adjustment.   But of course, serpentine belts have their own issues - they crack and dry out and stretch and the tensioners go south with regularity.

If your car is running normally, you should hear no noises at all.   However, if you have let the car sit for a while, particularly in a damp climate or if it was put away wet, you may hear some chirping on startup.  It is a regular "chirp, chirp, chirp" that gets progressively quieter until it goes away.  This is just rust from the pulleys working its way off.

However, as cars age, the tensioner (which is a pulley with a spring attached to it) may start to weaken, causing belt tension to loosen, which will cause chirping and squealing.   You will notice it when the A/C is turned on, or you turn the wheel hard (activating the power steering pump) or even turning on the headlights (causing a load on the alternator).   Some cars have separate belts for the A/C, and thus you can diagnose which belt has gone by listing for the squeal when you turn the A/C on.

In the old days when we had separate V-belts for every engine accessory, you could spot which belt was going South by listening for the squeal when turning the wheel (power steering pump belt) or when you turned on the headlights or some other electrical load (alternator belt).   The point is, you can figure these things out, if you listen carefully or even try.   A lot of folks "live with" squealing belts until they break and leave them stranded.  This is a shitty plan.

By the way, if you replace a belt that is going South, keep the old one in your spare tire well.   Belts can be hard to find, late a night on a Sunday, and the spare will get you home and a local gas station mechanci can replace it - or you can even do it yourself.   Save the old belt as a spare.

5.  Battery:   As I noted in earlier postings, if you are really astute, you can hear when a Battery is about to go South.   When you crank the engine you may hear it seem to be slightly slower that normal.  But this change is so subtle and takes place over time that few people notice it.

In the movies, they use a sound effect that was taken from a 1940 Dodge with a six-volt electrical system.  In those cars, when the battery went South, it would crank slower and slower and them stop cranking.   People expect that kind of behavior today from 12-volt systems, and it largely doesn't work that way.   Modern cars start one day and then don't the next.  All you hear is the "click" of the solenoid, and then not even that.

But again, if you are astute, you will notice that the car cranks a little slower than when new, and if the battery is a few years old (five or so) it may be time to replace it.   And if it was going bad, you will notice the difference with the higher-pitched sound when you start the car with the new battery.

6.  Tires:   Tire noise is annoying and wears on your spirit.  Here in Georiga we have "noisy pavement" that makes a grinding noise as you drive on it.   When you hit the Florida border - blessed silence!   Why this is, I don't know, other than I presume we use cheaper pavement.

But tires wear over time, and modern radial tires tend to "feather" as they wear.   Again, the process is gradual.  When the car is new, it is silent.  Over time, the tire noise gets louder and louder and you have to turn up the radio.

Rotating your tires is a good way to cut down on this noise and make them last longer.   If you run your hand over the tires, particularly the front ones, you may notice it feels smooth in one direction but catches your hand in the other.  This is classic "feathering" and it is somewhat normal.   The front-end of a car isn't straight, but instead, the tires are slightly (ever so slightly) pigeon-toed (what we call "toe-in") to keep the car driving straight.

This does cause more rolling resistance - and many car makers set very low toe-in at the factory in order to up gas mileage.  This in turn causes many modern cars to have a vague and wandering feel.   Our truck was this way, until we dialed in a little more toe-in, and now it tracks straight.

But over time, tires wear in a pattern and this pattern can cause noise.  Rotating the tires regularly (every 10,000 miles or so) can cause them to last 10,000 miles longer and also reduce tire noise.

And it goes without saying that before you decide to put "monster truck" tires on your truck or SUV you should think about tire noise.   The grinding noise you hear going down the road will wear on your nerves over time, cost you a lot in fuel economy, and cause a lot of tire wear.   And for what?   The appearance that you are going to go off-road but never do?   Just own up to reality and get regular tires and be happy.

* * * 

These are just a few sounds your car may make that you should be aware of - when they occur and when they stop occurring.   It always amazes me when someone says, "My car won't start!" and I ask them if the fuel pump is running.  "How would I know that?" they reply.  "Well, did you hear it kick on when you turned the key?" And they reply, "I dunno, I never notice those sorts of things!"

Similarly, when their A/C stops working,  you ask, "Well, did the compressor come on?  What about the auxiliary cooling fan?" and again you get the blank stare.   They know when their refrigerator or air conditioner is running in their home, but for some reason, the noises their car makes are an utter mystery to them.

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