November 5, 2025
Every combustion engine depends on a precisely timed air flow to operate efficiently. This task is performed by the valves. The intake valves regulate the supply of air in direct injection engines. In indirect injection engines, this is the air-fuel mixture. The exhaust valves regulate the discharge of combustion gases to the exhaust system. An incorrectly adjusted valve or poor installation can lead to compression loss, ignition faults, or even total engine failure. Understanding how valves work, the different types of valves, and how they should be properly installed and maintained is essential for anyone who works with engines.
A valve is a mechanical component that opens and closes at precise intervals, allowing air (or the air-fuel mixture) to enter the cylinder and the combustion gases to flow out of the cylinder.
Intake valves: these are usually larger and allow air (or the air-fuel mixture) to flow into the combustion chamber.
Exhaust valves: these are smaller and thermally highly resilient due to the use of high-quality materials, making them resistant to the extreme temperatures of the combustion gases.
The valves are part of the valve system, also known as the valve train, which consists of the camshaft, rocker arms, push rods, and valve springs. Depending on the design, they are driven by a single overhead camshaft (SOHC), double overhead camshafts (DOHC), or a bottom camshaft, using push rods. SOHC stands for Single Overhead Camshaft and DOHC for Double Overhead Camshaft.
Interesting fact: not all engines use valves. Rotary engines and two-stroke engines use ports instead.
Wilmink Engine Parts offers a variety of valve types tailored to different applications:
Standard steel valves – Reliable for everyday passenger cars and trucks. Brands such as TRW, MAHLE, Eaton, and Freccia are recognized suppliers.
Sodium-filled valves – Hollow valves filled with sodium that liquefies under the influence of heat and provides better heat dissipation. These are often used in turbo engines and heavier, high-load engines.
Bimetal valves – Made from different alloys to combine heat resistance with high material strength.
Custom-made valves – We offer tailor-made solutions under our Wilmink Engine Parts Private Label for industrial and marine engines, among others. In addition, together with the Ferrea brand, we can supply titanium valves for performance and classic cars, for example.
Whether you are maintaining a car for everyday use or building a race car, choosing the right type of valve is crucial for performance and durability.
Valves open and close millions of times, making them susceptible to wear and tear and defects. According to Kolbenschmidt the most common causes are:
Thermal overload – leads to burnt valve edges.
Poor lubrication – results in stem wear and stuck valves.
Improper installation – can cause breakage or poor sealing.
A well-known case involved broken intake valves in certain engines, demonstrating how material stress and thermal fatigue can play a role. Ensure that valves are properly maintained and installed. Symptoms of defective valves can include:
Engine misfires when idling or under load.
Reduced compression, leading to loss of power.
Unusual ticking or knocking noises.
Check the engine light, which is activated by ignition faults or leaks.
Installing valves is a precise job. Here is a clear step-by-step plan.
Thoroughly clean the cylinder head and remove all carbon and gasket residue.
Check the valve guides for wear. Replace them if the clearance between the valve and guide exceeds specifications.
Always replace the valve rubbers when installing new valves.
Use the correct installation tools to prevent damage.
Lubricate the valve stem with clean engine oil.
Carefully slide the valve into the guide without forcing it. Ensure that the valve can move freely in the guide.
Measure the clearance with precision tools.
Place the spring and valve head over the valve. Make sure that the spring fits properly in any recess in the cylinder head!
Use a valve spring compressor to compress the spring.
Install the valve collet in the groove of the valve stem.
Slowly release the spring compressor to lock them in place.
Always use new valve collets to prevent defects caused by worn or damaged valve collets.
The valve clearance (the small gap between the camshaft or rocker arm and the valve stem) ensures that the valve closes completely when necessary. Incorrect clearance can lead to:
Too tight: The valve may not close completely, which can lead to a burnt valve and loss of compression.
Too loose: Noisy operation, faster wear of the valve system, and loss of power.
Some engines require the valve clearance to be adjusted manually, using an adjustment bolt or valve adjustment shims. Other engines use hydraulic tappets that are self-adjusting and do not need to be adjusted manually.
The correct valve clearance is not a fixed value and varies depending on the engine brand. The manufacturer specifies the correct valve clearance, measured when the engine is warm or cold. Therefore, always consult the adjustment values for the relevant engine brand.
Measuring valve clearance requires professional tools to perform this precision work correctly. We can supply feeler gauges (WG1889229) from Kolbenschmidt for this purpose. Feeler gauges are used for:
Checking all types of clearance, including valve clearance.
General use in the workshop where exact measurements are required.
By using feeler gauges, you can be sure that the adjustments meet OE specifications.
Keeping valves and their components clean extends their service life.
Replacing valve cover gaskets – A worn gasket can leak oil, which can lead to ignition faults and even cause a malfunction warning on the dashboard when ignition parts or engine electronics are affected by the oil. Replacing the gasket in good time prevents contamination, malfunctions, and oil loss.
Cleaning EGR valves (diesel engines) – Carbon deposits restrict the recirculation of exhaust gases, increasing emissions. Regular cleaning of EGR valves restores proper operation and flow of exhaust gases.
Cleaning the throttle valve – Improves airflow to the engine and prevents irregular idling.
The use of special products such as EGR valve cleaner helps to effectively dissolve carbon deposits without removing or damaging the component.
Good quality valves for engines are essential for combustion, efficiency, and reliability. With proper installation, clearance, and periodic cleaning, they are ready for the next miles.
At Wilmink Engine Parts, you will find a complete range of:
Standard replacement valves.
High-quality sodium-filled and bimetal valves.
Fully customized valves for performance or special projects.
Need advice or help with products? Contact our specialists at sales@wilminkgroup.com. They will be happy to help you. Or fill in our customer form to request your own webshop account.
