In cars with an underhead camshaft, you will find a rocker arm. The rocker arm transfers the camshaft's movement to the intake valves. The rotating motion of the camshaft is converted into a vertical movement using a lever effect. The camshaft has oval lobes, which push against the pushrod, causing it to move up and down. This pushrod then presses against the rocker arm, which opens the valve.
Defective rocker arm
If a rocker arm is defective, it must be replaced. A broken rocker arm will no longer open the valves properly, causing incorrect valve timing, resulting in power loss and increased fuel consumption.
There are several symptoms that can indicate a defective rocker arm:
- Power loss: A defective rocker arm causes the intake valve's timing to be off. Correct timing is crucial for the intake and exhaust of air in the combustion chamber. The right amount of air at the right time ensures engine power.
- A stuttering engine: If valve timing is off due to a defect, you may notice a stuttering engine.
- A fast ticking noise: This sound is most noticeable when starting and stopping the car.
- The engine warning light is on: If there is a defect in one of the engine components, the dashboard warning light will illuminate.
Check the rocker arms if you recognise any of these symptoms. A crack or break in the rocker arm clearly indicates a fault, but if you notice metal debris under the rocker arm, this also signals a defect. You can compare the rocker arms to identify the problem.
Replacing a rocker arm
Is the rocker arm defective and do you want to replace it? You can do this job yourself. To replace it, you will need a ratchet, masking tape, and a new rocker arm.
Here?s how to replace a rocker arm:
1. Before starting, disconnect the negative cable from the battery to avoid short circuits during the replacement.
2. Next, remove the air filter and unplug the spark plug wires. Mark the spark plug wires with masking tape to ensure correct reassembly.
3. Then, detach the throttle cables from the throttle body. Remove the valve cover and the valve cover gasket.
4. Once everything has been removed and unscrewed, you can loosen the rocker arm nuts and remove the rocker arm.
5. Install the new rocker arm and tighten the bolts with a torque of 30 Nm using a torque wrench.
6. Then, reinstall the valve cover with a new gasket and reconnect the cables to the throttle body and the spark plugs.
7. Finally, reinstall the air filter and reconnect the negative cable to the battery.
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