Car engine camshaft: function, wear and maintenance
Car engine camshaft: the heart and rhythm creator of the engine
A car engine is a complex feat of engineering, with hundreds of parts working in perfect synergy. At the heart of this symphony is a component often referred to as the "brain" or "conductor" of the engine – the camshaft . While the pistons and crankshaft are responsible for generating raw power, it is the camshaft that determines when and for how long the engine "breathes".
What is a camshaft and how does it work?
The camshaft is a long metal rod with special egg- or teardrop-shaped cams designed on it. Its main function is to open and close the intake and exhaust valves at exactly the right time. Each cam corresponds to a specific valve. As the shaft rotates, the higher part of the cam (the lift) pushes the valve down (open), allowing the fuel-air mixture to enter the cylinder or the exhaust gases to exit. Springs push the valve back to the closed position when the cam has passed.
The movement of the camshaft is synchronized with the crankshaft. In a four-stroke engine, the camshaft rotates at exactly half the speed of the crankshaft. This synchronization is achieved either by a timing belt, a timing chain, or, in rare cases, by gears.
camshaft position: sohc vs dohc
In modern engines, we mainly encounter two types of solutions:
- SOHC (single overhead cam): one camshaft per cylinder head that operates both the intake and exhaust valves. Common in simpler and more economical engines.
- DOHC (Double Overhead Cam): Two camshafts per cylinder head – one for the intake and one for the exhaust valves. This allows for more precise valve timing, more valves per cylinder (e.g. 4 valves) and better power at high revs.
most common car models and their camshaft specifications
Various car manufacturers have had specific problems with camshafts and their actuators over the years. Here are some examples of common models:
volkswagen, audi, škoda, seat (vag group) 1.9 and 2.0 tdi
The legendary 1.9 TDI (especially the PD or pump injector versions) is known for its camshaft wear. Since the cam has to operate the fuel injectors in addition to the valves, the pressure on the cams is enormous. Using the wrong oil or having too long service intervals leads to the cams "sharpening" and eventually the hydraulic tappets breaking. Symptoms include a "thumping" sound in the air cleaner and loss of power.
BMW 3 Series and 5 Series (N47 and N57 engines)
In these engines, the problem is not always the camshaft itself, but its drive. The chain drive is located at the rear of the engine, which makes maintenance difficult. Stretching the chain changes the camshaft timing, which can, in the worst case, result in valves and pistons meeting.
Ford Focus and Mondeo (1.6 TDCI / PSA engines)
These engines use a small chain between the camshafts, which tends to wear out and cause rattling. If ignored, the chain can break, requiring an engine overhaul.
opel astra and insignia (2.0 cdti)
Aging of the engine oil pump seal can cause a momentary drop in oil pressure, which first damages the camshaft lobes and cam surfaces, as they are located at the furthest point of the lubrication system.
signs that the camshaft needs inspection
Camshaft failure usually doesn't happen overnight, but is the result of long-term wear. The following symptoms indicate a problem:
- A ticking or clicking noise at the top of the engine: This may indicate a worn cam or a faulty hydraulic lifter that can no longer compensate for the clearance between the valve and the cam.
- uneven engine idling: if the cam is worn, the valve does not open sufficiently, which disrupts the filling of the cylinder with air.
- loss of power at high rpm: the engine "hangs" because a worn camshaft does not allow sufficient gas exchange.
- "Check Engine" warning light: Modern cars monitor the timing using a camshaft position sensor (CMP). If the camshaft is worn or the chain is stretched, the engine goes into emergency mode.
Why does the camshaft wear out?
The camshaft is made of hardened steel or cast iron and should ideally last the life of the engine. However, there are several factors that accelerate wear:
- Insufficient lubrication: this is enemy number one. Oil is what creates a protective layer between the cam and the tappet. When the oil pressure is low or the channels are clogged, metal-to-metal contact occurs.
- wrong oil grade: specific engines require additives (e.g. zinc or phosphorus) that protect high-pressure surfaces.
- Fuel getting into the oil: failed DPF regenerations or leaking injectors dilute the oil, losing its lubricating properties.
well-known spare parts brands
When replacing a camshaft or its components, it is critical to choose a quality manufacturer, as the amount of work is large and there is little room for error. Well-known names on the market include:
- ina: probably the best known name in the world of camshafts, hydraulic tappets and chain kits. Original parts supplier to many car manufacturers.
- febi bilstein: a German quality brand that offers a wide range of camshafts and related parts for almost all car brands.
- ruville: specializes in engine components, offering durable solutions even for older engines.
- Kolbenschmidt (KS): Known for its precision and materials science, especially for halls and camshafts.
- SKF and Gates: Although known primarily for belts and bearings, they are indispensable when upgrading the camshaft drive (drive system).
Camshaft replacement – what do you need to know?
Replacing a camshaft is a complex procedure that often requires special tools to lock the engine timing. When replacing the camshaft, it is strongly recommended that you also replace:
- hydraulic tappets or mechanical tappets: an old worn tappet will damage the surface of a new camshaft very quickly.
- Camshaft seals (simmerings): to prevent oil leaks when installing a new component.
- Timing belt or chain: Since the engine has already been disassembled, this is the most sensible time to upgrade the drive.
- Oil and filter: A new camshaft needs clean and fresh grease for running in.
Image. Camshaft hydraulic lifters.
summary
The camshaft is a critical component for the longevity and efficiency of an engine. Its condition directly depends on the owner's diligence - high-quality oil and timely maintenance are the best ways to avoid expensive repair bills. However, if you notice the first signs of wear on your car, don't delay getting it checked. By using parts from reputable brands such as ina or febi, you ensure that your car's engine will stay in rhythm for many years to come.
Engine technology is constantly evolving, but the camshaft's role as a "conductor" remains as important in the twilight of the internal combustion engine as it was in the early days of the automotive industry.
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