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All Just just about Automobile CareThe Engine Explained
by:
Kevin Schappell
The engine is the heart of your car, but instead of pumping blood, the engine pumps air and fuel. The engines main function is to convert air and fuel into rotary motion so it can drive the wheels of the car. How makes it do that ??.... Well let's start with a cutaway of the engine and see all the major parts then we wish get into the actual mechanics.
Pistons: Most common engines have 4, 6, or 8 pistons, which come up and down in the cylinders. On the upper side of the piston is what is called the combustion chamber wherever
the fuel and air mix before ignited. On the different side is the crankcase, which is full of oil. Pistons have rings which serve to keep the oil out of the combustion chamber and the fuel and air out of the oil.
Crankshaft: The shaft
is connected to the pistons via a connecting rod. As the piston moves up and down in the cylinder it rotates the shaft
and converts the straight line motion into rotary motion.
Valve train: The valve train consists of valves, rocker arms, pushrods, lifters, and the camshaft. (shown in above image in blue, yellow, and green) The valve train’s only job is that of a traffic cop. It lets air and fuel in and out of the engine at the proper time. The temporal order
is controlled by the camshaft, which is synchronal to the shaft
by a chain or belt.
Now that we have a general summary
of the parts involved let's talk just about what happens. Most automotive engine now are 4-stroke (or 4-cycle) engines, meaning they have four distinct events which do up the cycle.
· Intake stroke: The shaft
opens the intake valve and the piston moves down the cylinder. This creates vacuum and sucks in air and fuel into the combustion chamber above the piston.
· Compression stroke: As the piston starts moving back up the cylinder the intake valve closes and seals off the combustion chamber. The causes the air and fuel to compress.
· Power stroke: As the fuel is compressed and the piston nears the top of the cylinder the spark plug fires and ignites the fuel and air. This explosion pushes the piston back down the cylinder and drives the crankshaft.
· Exhaust stroke: After the piston reaches the bottom of the cylinder, the exhaust valve opens and the gasses left over from the fuel and air are sent out to the exhaust system.
Put these four events together in the above order and you have a complete cycle. Are you asleep yet? That's enough theory, let's talk just about the real earth and problems you power encounter with the above mentioned parts.
Pistons: Remember I talked just about the rings, which seal the combustion chamber from the crankcase. The rings over time tend to wear out. Once
they wear they allow the fuel and air to enter into the oil and dilute it. This dilution reduces the oils ability to lubricate your engine and can cause premature wear. As well if the rings wear down they can allow oil from the housing
to enter the combustion chambers. This wish result in oil being burned and exiting your pipage as grayish/white smoke. If your car spews grayish white smoke and it makes not go finish in the 1st few minutes after start-up you power have warn rings. If the smoke goes away after start-up look to the valve train section.
Crankshaft: The shaft
rides on bearings, which can wear down over time. The bearings keep the shaft
and as well the rods, which connect the pistons to the crankshaft. A loud medium pitched sound
noise in the engine points to warn bearings most of the time. This is commonly a costly repair and involves removing the shaft
and either machining the surface wherever
the bearings ride, or commutation the entire crankshaft. To prevent this type of problem, use a high quality oil, change your oil at advisable
intervals (3 months or 3000 miles is a safe number) and always maintain your oil level between oil changes.
Valve train: Remember the oil smoke problem mentioned above in the piston sections. If your car only smokes grayish/white smoke at start-up you may have unseaworthy
valve seals. Valve seals keep oil from above the valve from unseaworthy
into the combustion chamber. Once
they wear, they can allow oil to course into the combustion chamber and collect there until your start the engine again. You generally do not get oil unseaworthy
past the valve seals patch the engine is running since the seals expand with the heat of the engine and plug the leak.
Another common problem is the temporal order
chain or belt wish slip or even as break deed the cam shaft to finish rotating. Remember the shaft
tells the valves once
to open and if it stops spinning then the valves finish opening and closing. No valve moving, no engine running :-)
A term you wish here once
talking just about temporal order
chains and belts is "interference engine". Once
an engine is an "interference engine" the pistons and valves are so close together that if the valves were to finish moving (broken belt or chain) and the shaft
unbroken
spinning they would-be crash into the piston. (that's the interference) This crash tends to do bad things to an engine, breaking valve, bending pushrods, and even as cracking pistons. This is why most manufacturers recommend dynamic the temporal order
chain or belt every 60,000 miles. Temporal order
belts dry out, stretch and deteriorate over time so even as if you do not have 60,000 miles on the car think just about dynamic the belt after it's 6 years old.
Preventive Maintenance:
· Change your oil regularly.
· Give your engine a chance to warm up before drive if possible. Let the oil get into all parts of the engine before driving. This is even as more critical in cooler temperatures once
the oil is cold and sluggish.
· Change your temporal order
belt or chain at your manufacturer's advisable
interval.
· void "snake oil" additives publicised
on late night TV. Regular oil changes and nice maintenance habits wish keep your engine running it's best.
· If you have a turbo charged engine, give the engine a minute or two cool down before turning it off. This cool down period allows oil to circulate and cool down the bearings. If you shut off the engine at once after hard driving, the oil can gum up about the hot bearings and create problems down the road.
What to discuss with your mechanic:
· If you have to replace your engine, discuss the benefits of purchase
used versus new. If you plan on keeping your car for several time, a new engine power be the better bet. Sometimes new engines are not more much costly than restored
ones, and offer the better solution.
· Once
trying to diagnose engine noises, be as synchronal as possible. Take note to once
the noise occurs; at what throttle position, and once
the noise started occurring. Sometimes dynamic the weight of oil being used can cause a new noise to crop up. Do sure you mechanic knows if you changed oil brands or weight recently.
Just just about the author:
Kevin Schappell maintains http://www.carbuyersclub.comwhere he gives proposal
on buying, selling, insurance, and financing. A mechanical engineer and car guy, Kevin has definite
to spend his online time serving others discover just about automobiles. To discover more just about how your car works, Kevin has createdhttp://www.mycarwizard.com
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