Things you must understand when grinding the Seating Valves OF Internal Combustion Engines
This post may not be giving you the whole details concerning the internal combustion engines rather it will center majorly on the grinding Valves operation in the internal combustion engines.
In the real sense, we are expecting you to go through our previous posts that gave more details concerning internal combustion engines and their various categories that will enable you to comprehend the real aspects of the engine this post will be covering.
First of all what is an Internal Combustion Engine Valve?
Every Internal Combustion Engines have either Four-stroke cycle or two-stroke cycle to make a complete combustion cycle. Though not all the internal Combustion engines have valves, majority of the four-stroke IC engines types do have valves on them.
Valves play vital roles in the internal Combustion Engines. The two major types of valves found in this categories of engine are the inlet or induction Valve and the outlet or exhaust Valve.
THE INLET OR INDUCTION VALVE
Before power stroke occurs in an internal Combustion Engine, there is an Induction stroke where the Piston travels down the cylinder to the down-dead-center, during this period the camshaft controls the inlet valve to open there by allowing enough inflow of air or Air-Fuel Mixture. During that Time the Camshaft controls the Exhaust Valve to remain closed.
This stroke is then followed by a Compression Stroke where the Piston returns back in other words, the piston tends to travel back to the Top-dead-center of the Cylinder. At this stage, the Camshaft controls the both the inlet Valve and the Exhaust Valve to remain closed. This stroke is known as the Compression Stroke stroke.
The high-pressure and Temperature built-up in the cylinder during the compression stroke makes it easy for the mixtures to ignite when the spark plug release a small spark from its bottom. The ignition will caused an explosive combustion of the the air-fuel mixture, hence the Piston will be forced to go down again due to the energy from the combustion.
During this stage, the two valves remain closed until the piston reaches the Down-dead-Center, to complete the power stroke.
While returning back to the Top-dead-center of the Cylinder the Exhaust Valve also Known as the outlet valve will be controlled to open through the Camshaft. The Opening of the Valve will force all the carbon monoxide which is a by-product of the combustion that took place to exit the exhaust valve.
This stroke is known as the exhaust stroke. It evacuates all the burnt gases out of the engine cylinder in order to initiate a cycle of four-strokes. Inlet Valve seating is usually wider in size than the exhaust-valve seating, except in few IC engines designs. Where the both can be found to be equal in size.
THE EXHAUST VALVE
As mentioned earlier, exhaust valve is just to help control the compressor stroke and power stroke and then assist to evacuate the burnt gases from the cylinder. The two cylinders are usually located above the cylinder where the two faces the piston head. The same position is where the spark-plugs and fuel injector can be found. The entire engine working operations are so synchronized that everything works according to timing for efficient and maximum power output.
Exhaust valve is usually connected to the exhaust cylinder through a small port that channels the exhaust gas out of the cylinder. The port-opening is where the Exhaust Valve controls. When, it opens, the gas will escape out of the cylinder through the port to the exhaust cylinder. From the exhaust cylinder the gas is diffused to the air in a controlled pressure and sound pollution reduction arrangements.
In terms of Size, Exhaust valve is usually smaller than the inlet Valve. And the exhaust valve is usually seen at the right-side or the end-part of the two Valves arrangements.
WHEN TO SERVICE THE ENGINE VALVES
Knowing when to service the Valves is very important for any auto-mechanic considering the fact that the entire engine efficiency depends on the accuracy or the Valves operations as well as their proper seating on the opening ports they are covering.
When there is a leakage in the valve ports, it affects the entire engine operations ranging from drop in power output to higher fuel consumption, incomplete combustion, and lots more. Some problems this can cause may not be noticeable except an experience engineer or technician access the engine carefully.
The right time to check the valve seating and to know if they need further servicing is when there is irregularity found from the engine especially when there is total incomplete combustion leading to black smoke coming out of the engine exhaust, there is significant power drop from the engine, there is unusual sound from the engine , etc.
THE SERVICES THE VALVES NEED
There are two major services the valve needs. One is to clean and adjust its seating to ensure total closure of the opening port when the valve is close. Ensuring there is no leakage means that the valve will not allow any entrance of air or fuel or allow any exit of engine gases once it is at the closed position. To achieve this service, the valve seating has to be grinded carefully to be able to seat properly on the cylinder head. The Next service will be to change the Valve once it can no longer make a proper closing of the ports irrespective of any grinding or adjustments made on it.
HOW TO GRIND A VALVE
To grind the engines the valves have to be removed from the engine by carefully dismantling all the valve springs and couplings. After that, clean the valve and scrap away smoke scales in the case of exhaust valve. Do the same to the port openings on the cylinder. Get a grinding powder.
Normally grinding powder comes in two forms, one is coarse and the other is smooth or fine. Open the Coarse first and rub a good quantity of it on the valve seating as well as the Opening port that the Valve usually make contact with when it is closed.
Position the valve the same manner the valve usually seat on the port and from the outside hold the valve tip with hand or a small electric motor powered machine. Rotate the valve at that position putting pressure by dragging the valve towards yourself.
For about 5 minutes, bring the valve out and clean the grinding powder on both sides. Then apply the smooth grinding powder. Repeat the same process for another 5 minutes. Then bring the valve out and clean the valve seating and the opening port with a diesel, fuel, or WD-40.
CONDUCT A LEAKAGE TEST
Having finished the grinding operation, the next good step is to ensure your operation was successful. To achieve that you will need to run a leakage test on the valve and the port. It the engine has four cylinders like in the case of car engines you may need to conduct the leakage test at the same time.
In that case, couple back the valves in their normal working settings, then fill up the ports with fuel or diesel, allow it for some time to see if there will be any minor leakage of the Fuel or Diesel coming out of the valve seating. If there is none, press the valve tip with impact force few times to see the instant fuel that escapes through the valve seating.
Once no leakage is seen after that, your grinding operation is successful. Otherwise you may need to repeat the process again or change the valve.
