ENGINE COMPRESSION TEST: HOW IS IT DONE?

1. WARM YOUR ENGINE UNTIL IT REACH THE NORMAL OPERATION TEMPERATURE

Engine compression test is done with engine is at normal operating temperature. Let it idle for 20 mins. then turn it off. Do not let your engine becomes too hot because it will be dangerous for the spark plugs to be removed when it is too hot that it might break and cause more problem to your engine.

2. IF YOUR FUEL PUMP IS ELECTRONICALLY OPERATED - DISABLE IT

Turn off or disable electronic fuel pump to avoid the fuel from being injected into the cylinders

3. DISCONNECT THE HIGH TENSION WIRES AND REMOVE ALL SPARK PLUGS

Disconnect all high tension wires and remove all the spark plugs(remember do not remove spark plugs if the engine is too hot). Disconnect the high tension wire from the ignition coil to cut the secondary circuit.

4. CONNECT THE COMPRESSION TESTER ON EACH CYLINDER - ONE AT A TIME

Connect the compression tester to spark plug hole at each cylinder. DO NOT USE WRENCH OR ANY TOOL WHILE TIGHTENING THE COMPRESSION TESTER. Do it with your bare hands only.

5. ASK A FRIEND TO CRANK THE ENGINE

A friend or an assistant will crank the engine several times while pressing the accelerator pedal fully while you are holding the compression tester and check the needle's movement. Crank the engine several times until the needle stops rising then record the final reading. This test should be done on all cylinders.

6. CLOSELY MONITOR THE NEEDLE'S MOVEMENT WHILE YOUR ASSISTANT IS CRANKING THE ENGINE

In every engine crank the needle in the tester should respond and rise. If the needle is not responding to the cranking of the engine then suddenly rises or have a reading then you might have a sticky valve. Servicing the valve will correct the problem.

7. COMPARE THE READING OF EACH CYLINDERS

Each cylinders compression should be close to each other. If one or two cylinders are 14 psi lower than the other it might be the piston rings or the cylinder linings are at fault. Do the compression test again but this time squirt a small amount of oil to the cylinder and let it still for a couple of minutes then do the compression test. If the compression changes; then the piston rings or cylinder are at fault. If not. the valves are at fault.

The video below is an example of actual compression testing

HOW TO: ENGINE COMPRESSION TEST

HOW TO: VALVE CLEARANCE ADJUSTMENT

Valve clearance adjustment is one of many maintenance needed by the engine to ensure that it is in good running condition. Incorrect adjustment may result to lack of air & fuel mixture to be supplied in each cylinder; or loose compression. Both intake and exhaust valves are adjusted to their specific clearance measurement depending on engine models and car manufacturer's specification.

There are two methods that can be used in valve clearance adjustment. The LONGER METHOD or per cylinder two valves to be adjusted every 180 degrees crankshaft turn. The other one is the SHORTER METHOD wherein you will position the no. 1 cylinder at Top Dead Center (TDC) compression stroke and then adjust four valves (depending on total number of valves of a certain engine model) at a time then rotate the crankshaft by 360 degrees and put the no.4 cylinder at TDC compression stroke then adjust the remaining four valves.

Below is a tutorial video that will help you understand easier how is it done

HOW TO: VALVE CLEARANCE ADJUSTMENT - FOUR CYLINDER ENGINES 8-VALVE

IGNITION TIMING - DISTRIBUTOR - MECHANICAL & VACUUM ADVANCE

Ignition timing, in a spark ignition internal combustion engine, is the process of setting the angle relative to piston position and crankshaft angular velocity that a spark will occur in the combustion chamber near the end of the compression stroke.

The need for advancing the timing of the spark is because fuel does not completely burn the instant the spark fires, the combustion gases take a period of time to expand, and the angular or rotational speed of the engine can lengthen or shorten the time frame in which the burning and expansion should occur.

Distributor is a device in a gasoline type engine wherein the electricity is transferred from the ignition coil to the spark plug thru high tension wires. Ignition timing can be advanced or retarded by turning the distributor. A use of timing light is highly recommended in adjusting ignition timing to ensure accurate reading and to avoid over-retarded or over-advanced timing. The distributor have essential parts that partially advancing the ignition timing depending on several factors like load; speed; driving habit; etc. These parts are called mechanical advance and vacuum advance. Properly working distributor advance will ensure that the ignition timing will be advance depending on the condition and driveability of the engine. Failure of the distributor advance will result to poor fuel mileage; loss of power; spark plug fouling (due to carbon deposit) and can result to engine failure.

Distributor will also require proper maintenance  just like carburetors to ensure that it will be dirt free and the moving parts will be lubricated.

The videos below will show what maintenance practices can be done to the distributor.

HOW TO: SET IGNITION TIMING W/ A TIMING LIGHT

HOW TO: UNINSTALL AND REINSTALL DISTRIBUTOR THE RIGHT WAY

HOW TO: DIAGNOSE DISTRIBUTOR ADVANCE - MECHANICAL AND VACUUM

CARBURETOR AIR AND FUEL MIXTURE

A carburetor is a device used in vehicles that blends air and fuel mixture for internal combustion engine in the proper ratio for combustion. Carburetor tuning is a very essential car maintenance to achieve the engine's peak performance. Improper air and fuel mixture will result to loss of power; too much fuel consumption; cylinder carbon build-up; etc.
A use of tachometer and a vacuum gauge is the most accurate way of tuning the carburetor. In the Philippines some mechanic are tuning the carburetor using plain hearing sense which is can be deceiving because of ones hearing condition. In the video below. you will learn how to properly tune the carburetor using the right instruments.

Toyota 4k Carburetor Idle speed & idle mixture adjustment