The exhaust valve is a crucial engine component. As part of the timing system, it enables the exhaust gases produced by combustion in the engine's cylinders to be discharged.
During the engine cycle, the exhaust valve opens at the end of the combustion phase to allow exhaust gases (combustion residues) to be discharged into the vehicle's exhaust system. Once the gases have been evacuated, the valve closes again to prepare the cylinder for the next cycle.
When the piston reaches its lowest point, the exhaust valve opens, allowing the burnt gases to be expelled under pressure to the exhaust manifold.Once all the gases have been expelled, the valve closes and the cylinder prepares for the next intake and compression cycle.
An exhaust valve that doesn't close properly can lead to exhaust gas leakage, reducing engine performance and power.An abnormal noise from the engine, such as a "rattling" or metallic knocking sound, may indicate that the valve is incorrectly closed or damaged.If the valve is not working properly, this can lead to inefficient combustion and increased fuel consumption.A faulty valve can cause incomplete combustion, resulting in excessive smoke emissions, including blue smoke (burnt oil) or black smoke (incomplete fuel).
As the engine ages, exhaust valves can become worn or deformed due to the extreme heat generated during combustion cycles.Overheating or poor thermal management can cause valves to crack or deform, preventing them from closing properly.Carbon deposits or other impurities can build up on the valve, impairing its operation.On some engines, valve clearances need to be adjusted regularly. If the valve clearance is too high or too low, this can affect valve operation.
Checking the condition of valves often involves dismantling the engine, removing the cylinder head and examining the valves and valve seats.If a valve is worn, cracked or damaged, it will need to be replaced. In some cases, it may be necessary to replace the valve guides or rectify the valve seats.In some engines (mechanical tappets), it may be necessary to adjust the valve clearances to ensure that the exhaust valve operates correctly. This adjustment should be carried out at regular intervals.Carbon deposits can be removed, but this may require careful disassembly and cleaning of the components.
In short, exhaust valves play a key role in engine operation and must be serviced regularly.
With a head diameter of 33 mm and a tail diameter of 9 mm, this valve is suitable for VW T2, T25, T3, 412, Type 4 engines:- 1700cc 62hp (CE 08/71 ->004 500)- 1700cc 66hp (CB 08/71 ->12/73)- 1700cc 66hp (CA 08/71 ->050 000)- 1700cc 80hp (W 08/69 ->250 000)- 1700cc 80hp (EA 08/71 ->098 793)- 1700cc 80hp (EB 08/71 ->010 020)- 1800cc 68hp (AP 027 466 ->055 000)- 2000cc 70hp (CJ, GE, CU, CV)- 2000cc 70hp (GD 000 001 ->055 800)
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