What is valve guide? What are the symptoms of a valve guide malfunction? Why does the valve guard wear out? What happens if you wear the valve guide ?….
What is Valve Guide?
Valve guides are also known as “valve guides” For most types of piston engines, they are used for each valve. The valve guides are cylindrical components that allow valves open and close easily without wobbling. Because of the rotational motion of the camshaft the guides move along with the valvespring, providing movement and stroke for the intake and exhaust vales. They also transmit some heat (about 25%), which is generated during combustion to the cylinder head.
For the production of valve guides, cast iron, steel and aluminum as well as bronze, brass, and other materials, are used. The basic characteristics of these materials include their low coefficients of friction and high thermal conductivity.
What is Valve Guidewear?
To ensure proper engine performance, the clearance between the valve guide’s inside diameter and the valve stem’s outside diameter is crucial. This clearance is necessary to lubricate and prevent the expansion va from getting stuck in a guide. For intake valves, the valve stem-guide clearance ranges between 0.25 and 0.75 mm. The gap between exhaust valves is between 0.50 and 1. mm due to extra heat. Diesel engines have higher clearances values than gasoline engines. Your vehicle’s make/model may have a different valve clearance. The valves could jam due to oil contamination and thermal expansion factor if the clearance falls below the limits. This can negatively impact the engine’s performance and cause guides to wear, bend, crack, and other problems. The valves will not be properly seated due to excessive running clearance.
As you can see, excessive clearance between the guide (and the valve stem) is a sign of valve guide wear. The guides can cause the valve plate to not fit properly in the seat of the valve (also known as the seat). This can cause compression loss and oil consumption which can lead to engine problems. If there are any doubts, it is important to check the manuals and replace them if they do not conform to the manufacturer’s specifications.
What are the symptoms of Valve Guide Malfunction?
Guide wear, particularly in the intake valves and other areas, can cause more serious problems. The vacuum at the intake valves can cause engine oil to be drawn into the engine and can contaminate spark plugs. It can cause the engine to emit more unburned Hydrocarbons (HC), which can raise emissions. Rapid carbon buildup can occur behind the intake valves as well as in the combustion chamber. Carbon deposits in the combustion chamber can lead to increased compression and even pre-ignition. For multi-point fuel injection systems, deposits behind intake valves can cause engine hesitation and irregularity. If the valve does not close completely due to carbon buildup, misfire symptoms can also occur.
The engine oil is drawn into an exhaust port in the event of damage to the exhaust valves. In newer vehicles, the catalytic converter is equipped with an oil filter to prevent oil from entering the exhaust system. This isn’t the only problem. The oxygen sensors will eventually fail, and the EGR valve may become blocked. This will cause the fault to spread to other parts.
Insufficient cooling and premature valve failure are another problem. Around 75% of the heat generated by the valves is retained in the seats, while 25% goes up to the body and is expunged from the guide. Newer engines have a higher heat transfer rate and the seats heat up more. The guides can fail and the valves may melt or wear due to heat. Wearing guides can also introduce unmetered air to the engine. This can cause engine problems such as misfires, excessive fuel consumption, and poor engine performance.
Valve breakage can also result from worn-out valve guides. When the valves open or close, the guides help to center them. A worn guide could cause the valve to wobble when it opens or slide out from the seat. Each time the valve is closed, the valve plate can bend slightly. Due to millions of work hours, the metal can wear out and the valve plate could come off of the stem.
You may notice blue smoke from your cold engine’s exhaust when you start it. It could be due to worn or damaged valve rubbers. Most often, the leftover oil from your last ride builds up in the valve cover. This oil is then drawn into the combustion chamber by worn guides and damaged valve tires. This causes the engine’s oil to burn and produces blue smoke. If excessive smoke is coming from the exhaust, it is likely that the problem is deeper in the piston rings. It is easiest to distinguish the two by having the engine compression checked. The fault lies in the valve rubbers, guides, or piston rings if the compression is too high. Both cases require professional diagnosis and repair.
