Joe Clark dropped the
receiver onto its hook and poked his head through the doorway that led to the
Model Garage repair shop.
"Tom Messler was just on the wire, Gus," he called
to his gray-haired partner who was half hidden under the head of a motor.
"He's stranded out on the
and wants you to come and get him."
"What's his trouble?" Gus
Wilson asked as he tugged at the end of a wrench.
"Out of gas, I suppose."
"Claims he's out of oil,"
explained Joe with a shrug, "But I just checked it for him the other day and it
was right up to the mark."
"Well, I was about to quit
for the day, but I don't suppose we can let a friend spend the night on a lonely
road," Gus decided as he rubbed his hands on a wad of waste.
"Grab one of those six gallon cans of oil and I'll meet you at the
In less than twenty minutes,
the Model Garage tow car, with Gus at the wheel and Joe perched on the seat
beside him, pulled up behind a small sedan.
Tom Messler's head was framed in the car window as he greeted the two
"My crankcase has sprung a
leak," he sputtered critically.
"She's almost dry. First thing I knew, my pressure gage started to drop as I
stopped and took a look at the oil and she's less than one-third full."
While Messler talked, Gus
peered under the car and then walking to the rear, followed the general route
the car had taken for several hundred feet.
When he returned, he was shaking his head.
"Most of your oil is back
there on the road," he announced as he slipped his flashlight into his hip
pocket. "Been noticing any puddles
under your car when it's been parked?"
"Not particularly," Messler
replied, "In fact, it was only this morning that I noticed how clean the garage
"That's funny," mused Gus.
"And there's no sign of oil underneath now.
The stream ends about three feet back.
The means the leak stopped when you stopped your car."
"Do you suppose the drain
plug or the crankcase bolts are loose?"
put in Messler.
"No such luck," replied Gus.
"Chances are it's the rear main bearing.
But there's no sense guessing.
Let's hoist her up and tow her in.
We'll drop you off at your house and you can stop in at the garage
tomorrow and I'll go over it with you."
Gus was a little late getting
to the garage the next morning and Tom Messler was there waiting for him.
"Well, what's the verdict"
the car owner called as the veteran mechanic entered the repair shop.
"There she is," Gus replied,
extending a large thumb in the general direction of his bench.
"Soon as I can get into my work duds I'll be with you.
"You can blame two things for
that little oil leak that left you stranded last night," Gus explained as he
joined Messler beside the open hood of the car.
"Burned piston rings and a
clogged breather cap on the oil filter pipe.
The combination of the two forced the oil through the rear main bearing."
"But what's a breather cap
got to do with a bearing?" asked Messler.
"Plenty," Gus asserted.
"In the first place, your piston rings are just worn enough to be leaky.
Naturally, any gas that blew by collected in the crankcase.
Under ordinary conditions that wouldn't be so bad but in some way your
breather cap got clogged with dirt and goo.
That closed up your crankcase tighter'n a corked bottle and the gas
couldn't escape. Something had to
give, so the gas just forced the oil out at the bearing.
"I've seen lots of small oil leaks
caused by nothing more than a clogged breather.
Even without leaky rings, the up and down motion of the pistons will
actually pump up enough pressure to force the oil out if it fails to escape
through the breather," he explained to Messler.
"Moral: always see that your
breather cap is clean when you check the oil," concluded Messler when Gus had
"You know, Gus, I never
thought much about my oil until last night when I didn't have any.
I never added any between oil changes."
"But that doesn't mean you
weren't losing some," put in Gus.
"The oil level stayed pretty
much the same," argued Messler.
"That's possible," Gus
agreed. "With the blow-by that
motor has, enough gasoline probably leaked into the crankcase to make up for any
you lost. In every explosion of a
cylinder there's a certain portion of the gas that doesn't burn completely.
Finally, it's forced by the pistons into the oil.
Then, there's the mixture that collects in the cylinders.
That ends up in the oil too."
"Moisture," repeated Messler,
"where does that come from?"
"It's formed when the gas
burns," explained Gus. "It's one of
the products of combustion. Let's go
out in the driveway, Joe has his car parked out there and with a little
experimenting I think I can show you what I mean."
On their way to the car, Gus
recruited Joe, who was busy working on some bills in the garage office.
As Joe started his car, Gus, sitting on his haunches, held a shiny piece
of scrap metal near the end of the exhaust pipe.
As the gases struck the metal, a misty coating of water turned out its
"You see," Gus said, pointing
to the tiny droplets that beaded the metal, "water and unburned gasoline.
It's our old enemy dilution.
Every car has it, but leaky pistons and rings allow more of it to reach the
"Isn't there some way to
prevent it?" asked Messler.
"Sure, but you can't
eliminate it entirely. The best
safeguard is to keep your motor in good condition.
As for your driving habits, don't use your choke any more than you have
to. You know, Tom, you
probably won't believe it, but every time you yank your choke buttons all the
way out to start a cold motor, you force several ounces of new gas into your
"Fouled spark plugs and a
skipping engine help to dilute the oil, too.
Some of the unburned gas is bound to find its way past the pistons into
the crankcase. And a carburetor
that's set too rich will do the same thing."
"How can you tell when your
oil is so diluted that it isn't doing its job?" asked Messler.
"There's no way that's
particularly accurate," confessed Gus.
"Maybe some day automobile manufacturers will equip their cars with some
sort of dashboard meter that will measure the viscosity or thickness of the oil
in the crankcase. Until then, the
safest thing is to change your oil regularly.
"Of course, you can check it
to some extent by watching your oil pressure gage.
If the reading drops down to about half of what it was when you put in
new oil, it's a fairly good sign that the oil is getting thin."
"Aside from dilution, why is
it that some cars use more oil than others?" interrupted Messler.
"In most cases," advised Gus,
"it's just a little reminder that the motor isn't running as well as it should.
Of course every motor is bound to use some oil, but when adding oil get
to be a habit, look for trouble. Bad
bearings, loose-fitting piston rings, sprung connecting rods, and worn or scared
cylinders are just some of the faults that show up in the oil hogs.
Then there are leaks of all sorts.
"The way you
drive has a lot to do with how much oil a car uses," went on Gus.
"A motor that's running at high speed or up long pulls is bound to bust
up. Naturally, the oil will get thinner and weaker.
Hot, thin oil not only leaks easier but it's bad for the bearings.
It pits the Babbitt metal and makes it crumble.
That's why some of the new cars are fitted with oil coolers.
The oil is water-cooked.
"Then too, the faster you
drive, the faster your oil pump will work and the pressure of the oil will
increase. High oil pressure will
force more oil into your cylinders and possibly through the bearings."
"Say, listen," grinned
Messler, "Before you think of any more troubles, what's to be done with my car?"
"Well," Gus drawled, "you
could get by with those rings for a while as long as the breather is open and
the crankcase is ventilated. But to
make a good job of it, I'd suggest new rings and a recondition job on the
"Phew!" sighed Messler.
"The way you were going at it a few minutes ago I expected nothing less
than the advice that I get a new motor.
Well, give her the works, Gus.
Might as well have it done now as later on when things may get worse.
Besides I may be able to save a little on oil."
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