The Engine ExplainedWritten by Kevin Schappell
The engine is heart of your car, but instead of pumping blood, engine pumps air and fuel. The engines main function is to convert air and fuel into rotary motion so it can drive wheels of car. How does it do that ??.... Well let's start with a cutaway of engine and see all major parts then we will get into actual mechanics. Pistons: Most common engines have 4, 6, or 8 pistons, which move up and down in cylinders. On upper side of piston is what is called combustion chamber where fuel and air mix before ignited. On other side is crankcase, which is full of oil. Pistons have rings which serve to keep oil out of combustion chamber and fuel and air out of oil. Crankshaft: The crankshaft is connected to pistons via a connecting rod. As piston moves up and down in cylinder it rotates crankshaft and converts straight line motion into rotary motion. Valve train: The valve train consists of valves, rocker arms, pushrods, lifters, and camshaft. (shown in above picture 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 engine at proper time. The timing is controlled by camshaft, which is synchronized to crankshaft by a chain or belt. Now that we have a general overview of parts involved let's talk about what happens. Most automotive engine today are 4-stroke (or 4-cycle) engines, meaning they have four distinct events which make up cycle. ·Intake stroke: The camshaft opens intake valve and piston moves down cylinder. This creates vacuum and sucks in air and fuel into combustion chamber above piston. ·Compression stroke: As piston starts moving back up cylinder intake valve closes and seals off combustion chamber. The causes air and fuel to compress. ·Power stroke: As fuel is compressed and piston nears top of cylinder spark plug fires and ignites fuel and air. This explosion pushes piston back down cylinder and drives crankshaft. ·Exhaust stroke: After piston reaches bottom of cylinder, exhaust valve opens and gasses left over from fuel and air are sent out to exhaust system. Put these four events together in above order and you have a complete cycle. Are you asleep yet? That's enough theory, let's talk about real world and problems you might encounter with above mentioned parts. Pistons: Remember I talked about rings, which seal combustion chamber from crankcase. The rings over time tend to wear out. When they wear they allow fuel and air to enter into oil and dilute it. This dilution reduces oils ability to lubricate your engine and can cause premature wear. Also if rings wear down they can allow oil from crankcase to enter combustion chambers. This will result in oil being burned and exiting your tailpipe as grayish/white smoke. If your car spews grayish white smoke and it does not go stop in first few minutes after start-up you might have warn rings. If smoke goes away after start-up look to valve train section. Crankshaft: The crankshaft rides on bearings, which can wear down over time. The bearings support crankshaft and also rods, which connect pistons to crankshaft. A loud medium pitched knocking noise in engine points to warn bearings most of time. This is usually a costly repair and involves removing crankshaft and either machining surface where bearings ride, or replacing entire crankshaft. To prevent this type of problem, use a high quality oil, change your oil at suggested intervals (3 months or 3000 miles is a safe number) and always maintain your oil level between oil changes.
How to Change A TireWritten by Kevin Schappell
It always happens at worst times! You need to know how to change a tire even if you have an auto club membership. Depending on where you get a flat, there may not be a phone nearby to call a tow truck. Let's take is step by step and always remember to read your owners manual, there will be detailed instructions relating to your car there. I should mention also a few tips for getting to side of road safely if you have a blowout on road. ·Stay calm, do not panic ·Slowly take your foot off of gas and let vehicle coast to a stop. ·Do not make any sudden braking or steering actions. ·Put your flashers on to alert other drivers. ·Now that you are safely off of road. Step 1: Make sure you are on firm level ground and away from traffic. If you are not, then try to drive to a better spot, but only if you can do it safely. Avoid going back onto road and into traffic. Step 2: Set your emergency brake and put car in Park or 1st gear if you have a manual transmission. Make sure engine is turned off. Step 3: Locate spare tire, jack, and lug wrench. These are usually located in trunk underneath carpet on cars. Trucks usually have jack and lug wrench behind seat or under hood, with spare tire under bed. Step 4: Typically there are instructions printed on jack or somewhere near storage compartment. Read these instructions, they will tell you where to jack vehicle and any special steps you will need to take. Step 5: First remove hubcap or wheel cover. The lug wrench often has a flat end, which you can use to pry off cover. If not, a screwdriver will work just fine. Step 6: Before you jack car up you will want to break loose lug nuts. The weight of car will keep wheel from spinning and allow you to apply more force to nuts. You do not want to completely remove lug nuts yet.... just break them loose. Once lug nut begins to move, STOP and move onto next one. I often carry a small pipe, which will fit over lug wrench. This pipe can provide additional leverage and allow you to get those stubborn lug nuts off. Always remember righty tighty, lefty loosy. Turn lug nuts left or counter clockwise to loosen.