What is a Cam Phaser? Symptoms and Replacement Cost

by James Clayton
Cam Phaser

Almost all late-model motors are equipped with variable valve timing (VVT). Depending on the device configuration, generation can improve engine performance, reduce emissions, increase gasoline economy, or all of the above.

One or more camshaft actuators—also called camshaft phasers—act as the heart of a VVT machine. When the conditions are right, the engine valves change the position of the phaser camshafts to control timing.

Although camshaft phasers sound over the top in concept, they are not uncommon failure factors for many modern engines. It’s helpful to have a basic understanding of phasers in case you ever need to replace them for your car.

What is a Camshaft Phaser?

Camshaft Phaser

Some automobile manufacturers refer to camshaft actuators as phasers, while others use the same term. However, regardless of what they are called, all phasers serve the same purpose: to adjust the position or “phase” of the camshaft with respect to the crankshaft, thereby changing the timing of the valve.

To understand the concept better, it helps to first identify the camshaft, valve, and variable valve timing.

How do the Camshafts and Valves work?

Inside the engine are a crankshaft and one or more camshafts. The camshaft opens and closes a series of valves that allow air (and fuel, in the case of port injection) into the engine and exhaust gases.

The timing chain (or timing belt) connects the crankshaft to the camshaft.
The timing chain (or timing belt) connects the crankshaft to the camshaft.

Meanwhile, the crankshaft is connected to the connecting rod and piston. When the car is running, the valve allows air to enter the engine’s cylinders and mix with the gas. The aggregate is ignited by a spark plug, which develops a series of small explosions. Each detonation pushes a piston down inside the engine.

The movement of the pistons rotates the crankshaft, increasing the rotational pressure to propel your car down the road.

The timing chain (or timing belt) connects the crankshaft to the camshaft. The shaft must be aligned so that the valve opens and closes at the correct point in the piston’s travel.

How do variable valve timing and phasers work?

In a conventional engine, the valve timing (when the valve opens and closes) is constant. But with a sophisticated VVT device, the placement of the camshaft can be adjusted, thereby changing the valve timing. Having this capability can improve engine performance, increase gasoline economy, or both.

Some special additives work collectively within the general VVT system. Most automobiles use hydraulically operated phasers (aka actuators) located at the ends of the camshafts to alter camshaft function and to retard or extend valve timing.

An oil manipulation solenoid (often called a VVT solenoid), applies oil tension to set the phaser. The PCM controls the VVT ​​solenoid entirely based on inputs from various sensors. Generally, there is one VVT ​​solenoid for each phase.

Some simple motors have phasers on either the exhaust camshaft or the intake camshaft, while others have phasers on each. It is worth noting that different automakers have specific naming conventions for their VVT systems.

For example, Ford refers to its device as Bilaterally Variable Camshaft Timing (Ti-VCT) and BMW calls its setup Vanos.

What happens when a cam phaser goes bad: three common symptoms

Cam phasers are a common problem in many modern vehicles. Ford, in particular, is known for phasing out problems in its gas-powered full-size trucks and SUVs.

If your vehicle’s cam phaser starts to fail, you may experience one or more of the following symptoms.

1. Illuminated Check Engine Light

Your car’s engine computer, called the Powertrain Manipulate Module (PCM), displays the position of the camshaft(s) via a video display of one or additional camshaft position sensors. If the module detects that the camshaft has deviated from its expected position (due to a faulty phaser), the module will gently activate the test engine and store a diagnostic trouble code in its memory.

2. Poor Engine Performance

A faulty phaser valve can prevent timing from moving forward or backward as needed. As a result, the engine may exhibit performance problems, such as rough tread and poor acceleration.

3. Rattling Noise

The Max phaser is designed to be mounted in a roll on the base idler. However, when the phaser fails, it cannot stop in the area, resulting in a rattling or rattling noise from the top of the engine. Noise is loudest at idle when the engine is warm.

What Causes the Cam Phaser to Fail?

1. Low Oil Pressure

Each cam phaser requires the correct amount of oil pressure to offer power. When the tension is missing, the cam phaser will go through a terrible. You may be experiencing oil stress in your vehicle due to a leaking oil well or oil pump failure. Bad oil stress can also occur in phasers because they are made of steel and require lubrication.

2. Wrong Oil Viscosity

You must use the correct oil viscosity for the engine to ensure proper friction and lubrication. Engines are constantly running at extreme temperatures and the wrong viscosity can cause a lot of damage. By using the right oil, you also ensure the right pressure. Otherwise, the cam phasers will react slowly and damage will occur.

3. Contaminated Oil

As oil ages, it becomes contaminated with mud, dust, and debris. All those factors reduce the oil weight, which affects the beauty of the cam phaser. That’s why you should always change the oil at the right time. If you use synthetic oil, you won’t need to trade it in as often as conventional oil. Don’t forget to exchange the oil filter at the same time to make sure the fluid stays sparkling.

4. Damaged Gear/Sprocket

Motor oil also helps lubricate the gears and sprockets. If there is an excessive amount of friction, these precious elements will already fail, mainly cam phaser problems. If you are concerned about proper lubrication, you can add a constant friction modifier for very short stretches. But, these days top oil manufacturers provide everything needed to keep the engine running smoothly.

How Much Does it Cost to Replace Cam Phasers?

Replacing cam phasers is not cheap. You can expect to pay anywhere from $800 to $2500 for a professional to do the job. Of course, the exact price will depend on several factors, such as the year, make, and model of the vehicle.

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