I just started my 4 weeks course of automotive engine on June 14th. We were given n now still working on examining basically everything about the Toyota engine 4A-FE and also have been given the manual with all the specs n stuff. So this is the central tech of the car, the base of the miracle. As far as i know 4A-FE is an inline 4 cylinder DOHC( it has 2 over head cams- 16/4 valves), 1.6L (standard for 4A), descendant of the carbureted 4A-F so i guess "E" stands for electronic fuel injection 'cuz it does use it. This is also a very basic but a modern day engine with the purpose of fuel economy, of course there are others variation for performance.
So what to tell here this is a 4 strokes, petrol, max 113 hp @ 6000rpm pretty standard actually. The good thing is our one is pretty well-preserved n in basically good condition.
On our first day we were assigned to strip out the engine. There are me and another guy so we were supposed to divide task and apparently i'm taking the cylinder head and he's taking the cylinder block which is also called short block. The reason 4 this is there are 2 manual for each part it means that Toyota wants us mechanics to treat the engine as 2 main parts nt 1 unit. I can also clearly see that those 2 parts are very separated when it comes to stripping down so.
Lets get down 2 business shall we! First we had to take the cylinder head out so i can take care of the head and my buddy is able to take car of the short block. Giving u guys some heads up there is a large gasket that fits the entire area dividing between short block and head block. Cylinder head basically contain all the government controls of the valves that inlet and exhaust the combustion chamber. That consists of 2 camshafts which have lobes to lift or push the poppet valve up n down, numbers of lobes are correspondent to numbers of inlets and exhaus valve, n they are set up in different bearings for each cylinder. This is simply because there are 4 cylinders and firing order is important as it maintain the smooth, continuous output generation to the flywheel for maximum mechanical efficiency and least maximum vibration.
There are 2 camshaft one is intake n is exhaust as i can tell the intake from the exhaust because the intake sits in the place where it is hooks up with the valve timing actuator. It is also important that you know the front n rear of the engine, obviously where there are pulley n the timing belt thats the front and the rear is with the flywheel- the output of an engine. Also, intake valve always bigger than the exhaust valve, why, because intake is the large volume of air n fuel; exhaust is the discard of compressed, burned gas.
Right underneath the combustion chamber is the crankcase where is the crankshaft and all of its weight balancing for the same purpose. One thing I should remember about the engine is it might be 2-3 units when stripping but when it's put together it operates like a one impeccable unit. Every motion, every combustion is in timing, sequence hence needs to fit perfectly and set correctly in its place. The way the valves open n close are mechanically automatic thanks to the cams, while they are driven by a timing belt driven by the crankshaft pulley. EVERYTHING, fitted, timed and operate in an unchanged pattern.
So what I'm doing is taking care of the cams, and all the valves. And my partner is taking care of the cylinders, the chambers, the crankshaft...all the under parts. As I mentioned before everything is mechanically automated so a fixed order allows no individual or unresponsive change, so is the compulsory stripping in order process. After the head cover, I literally have to number mark all the bolts, keepers, springs, valves as I strip them out with a numerical order and putting them back in a reverse order. With the bolts, order helps balance out the amount of load that each bolt have to carry, because when you take out this position the bolts at other position might be under heavier load. With the valves and springs, because there are going to be a huge number of tests with all sorts of tools and units like length, diameter, wears, compression ratios etc... I need to know individually where they came from. Because each group of valve through time are like bonded with their cylinder, what effects the combustion has on this cylinder are all relative to what effects are on the valves, springs. If I mixed them up, and my engine went wrong i would never know which valve is the source for that cylinder's misfire, etc...and...That's it for now.
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