Hydraulic Timing Belt Actuator
- The timing belt keeps the revolution of the crankshaft and the camshaft/s in perfect rhythm, so cylinders can fire in the correct order.
- On some drive belt systems, a hydraulic timing belt actuator, also known as a hydraulic tensioner, is used to keep the belt taut, so it can turn easily with the gears and pulleys without slipping and making a lot of noise.
- Because of the actuator’s stroke length and the tensioner’s lever design, they can better deal with dynamic belt forces and behaviors.
- The hydraulic timing belt tensioner starts to fail or underperform when the tensioner pulley bearing and the actuator wear out as they age, when the tensioner becomes contaminated, and when the actuator seal leaks.
- Symptoms of a bad tensioner include squealing, chirping, grinding, or rattling from the pulleys or from the timing cover; knocking around the timing cover and other components inside it; and engine troubles such as misfires, no-start condition, power loss, and drivability problems under high loads or rpm.
- Aside from the timing belt kit, the hydraulic timing belt actuator may be sold along with a water pump, a head gasket set, a cylinder head bolt kit, or a valve cover gasket.
Camshafts must rotate at half the speed of the engine crankshaft. The timing is controlled by the toothed belt that is interlocked with their cogwheels. As they roll along with the timing belt, the valves open and close just as the pistons travel up and down for the intake and exhaust stroke.
The timing belt keeps the revolution of the crankshaft and the camshaft/s in perfect rhythm, so cylinders can fire in the correct order. If the valves open too soon, this will lead to inefficient combustion, insufficient pressure, and power loss. When engine parts are totally out of sync, the pistons may collide with the valves, causing a catastrophic engine breakdown.
The timing belt is not only used for maintaining a specific drive ratio. This rubber winds over and through pulleys and gears to drive other components and accessories as well, including the alternator, power steering pump, water pump, and compressor on newer vehicles. On some drive belt systems, a hydraulic timing belt actuator, also known as the hydraulic tensioner, is used to keep it tight, so it can turn easily with the gears and pulleys without slipping and making a lot of noise.
How a hydraulic tensioner works
On some engines, the drive belt system is equipped with a hydraulic tensioner, which consists of a hydraulic actuator and a tensioner pulley. The actuator is built with a cylinder housing, a piston rod, a piston, a spring, a retaining valve, and a one-way pin. It also has oil and air in it. The actuator’s piston rod moves in one direction. The movement is guided by oil that runs from one end to the other end through the one-way valve. Through the lever, the movement of the piston rod is transferred to the pulley.
The hydraulic tensioner system is used mainly on V6 or V8 applications or where angular vibrations are common. Compared to mechanical tensioners, hydraulic tensioners are more flexible since they can be used on a range of dynamic belt lengths. Even when the length of the belt changes due to thermal expansion, these tensioners can maintain constant belt tension.
Because of the actuator’s stroke length and the tensioner’s lever design, they can better deal with dynamic belt forces and behaviors. They can effectively handle any loss in timing belt tension due to changes in engine temperatures and speed or overall wear. They are well equipped to deal with dynamic belt behaviors or loads through high unidirectional hydraulic damping, wherein the piston rod is pushed inward to displace oil in the cylinder. These characteristics not only keep the belt tight and quiet but also effective in transmitting power even with the changes in tension.
Why replace the timing belt tensioner
The hydraulic timing belt tensioner starts to fail or underperform as the tensioner pulley bearing and the actuator wear out. This is what normally happens when they age. The hydraulic tensioner system can also become contaminated. The actuator seal may break, and this will cause an oil leak. The leak does not have to be wide or large before this may cause wear or start to weaken the damping abilities of the tensioner.
Over time, the constant movement of parts can place a lot of stress on the tensioner. Although this is designed to easily accommodate changes leading to loss of tension, it can only hold out for so long before it is strained enough to break down.
Usually, it is the tensioner that gives out first, unless the belt is already stretched out and burned due to age. Because of a bad tensioner, the pulley can seize up and the belt can come loose. When the belt comes in contact with the timing cover, this will cause more than just a fracture on the rubber. A damaged belt can result in a costly engine failure.
How to tell if the timing belt tensioner has failed
Once the tensioner wears out, the timing belt will become slack. Valve timing will be off, and this will set off a trouble code or trigger the check engine light to flash on the dash. This symptom may be combined with other signs of impending failure, such as:.
A bad tensioner will make all kinds of noise. Since a loose timing belt will no longer have a firm grip on the pulleys, you may hear some squealing or rattling from the pulleys or from the timing cover. Once the pulley bearing fails or goes bad, they will squeal or make some grinding noise.
A timing belt that is not properly tensioned will knock around and may even bang into the timing cover and other components in it. This will be accompanied by a slapping sound.
A failing tensioner cannot keep the timing belt tight. The engine crankshaft and camshaft/s will not be synchronized because of this, and the valves will not be timed properly. This will lead to a host of engine problems. The engine may fail to turn over. When turning on the ignition, the motor may start whirring or clicking but will not start as the air-fuel mixture fails to ignite in the chamber. Engine misfires will also happen when the valves open or close too soon. The vehicle will suffer from loss or lack of engine power and drivability problems under high loads or rpm.
Visible signs of damage
Aside from a loose timing belt, there are visible signs of damage that you can spot on the tensioner. You may find rust bleeding through the different parts of tensioner assembly or find some chips, cracks, dents, bends, streaks, or gouges. You also have to check the alignment.
How to find the right timing belt tensioner replacement
The timing belt tensioner replacement should match the specific application or drive belt system of your vehicle. Tension should not be too low, which will make the belt slip or wear out easily, nor too high, which will cause excessive wear on belt-driven parts and accessories.
Hydraulic timing belt actuators can be bought per unit, although when replacing the tensioner, it is a good idea to replace the entire timing belt. The tensioner is available in different sets. Aside from the timing belt kit, the hydraulic timing belt actuator may be sold along with a water pump, a head gasket set, a cylinder head bolt kit, and a valve cover gasket. The set may include all or just some of these parts, depending on what your vehicle needs.
Replacing Your Hydraulic Timing Belt Actuator
The hydraulic timing belt actuator is a device that ensures that the timing belt of a vehicle is wound tight enough around the necessary gears of the engine. It does its job together with the timing belt pulley. As the name suggests, timing belts make sure that various components in the engine run smoothly in the correct order. A malfunction with the actuator can cause the timing belt to go slack which in turn means that the gears in the engine compartment won't properly rotate. A number of moving parts in the engine will then stop moving in sync with one another and this could lead to a catastrophic engine failure that could cost you thousands of dollars. Don't wait for that moment to happen, replace your timing belt actuator as soon as you sense a problem with it.
Difficulty level: Moderate
Tools that you'll need:
- Hydraulic timing belt actuator
- Socket wrench
- Screw Driver
- Allen wrench
Removing the old hydraulic timing belt actuator
Step 1: Locate the timing belt of your engine. Consult your vehicle's manual to do so. The timing belts of most cars can be accessed from the hood of your car while some can only be reached underneath. Other vehicles require the removal of a number of engine components before you can reach the timing belt. Make sure to do the necessary steps required.
Step 2: Locate the timing belt pulley. Just follow the timing belt around until you see it. The pulley is usually in contact with the smooth side of the timing belt. You can also see hydraulic timing belt actuator attached to it.
Step 3: Loosen the timing belt pulley to loosen the tension of the timing belt. Doing so may require different methods depending on the manufacturer so consult a manual.
Step 4: Remove the bolts securing the timing belt pulley and slide the pulley out of its housing or mount.
Step 5: Remove the bolts securing the hydraulic belt actuator before removing it as well.
Installing the new hydraulic timing belt actuator
Step 1: Secure the hydraulic timing belt actuator to its place by tightening the appropriate bolts. Be careful not to pull the hydraulic timing belt actuator's retaining pin.
Step 2: Reinstall the pulley and secure it.
Step 3: Put the timing belt back on the pulley and around the proper gears. Make sure it is tight enough and in its proper place. Crank the whole pulley a bit just to be sure.
Step 4: Remove the retaining pin attached to the hydraulic timing belt actuator.
Be sure that your engine is cool before working on it. If car your was running just prior to your installation attempt, then abort your repair attempt and leave it for about 30 minutes before trying again.
Do not remove the pin of the hydraulic timing belt actuator until it is installed in the engine. Doing so can mix up the air and the oil contained within. If the pin has be removed accidentally, put the actuator in an upright position and compress the piston rods to separate the oil and the air.