What is a rocker arm?
A rocker arm is the part that receives motion from the camshaft and pushes the valve stem (intake or exhaust) to open and close at the right time. Think of a seesaw: the cam pushes one end, and the valve moves down at the other.
The channel's engines use two main types of rocker arm:
- Mechanical rocker arm with an adjusting screw — used in air-cooled VW engines (Brasília/Fusca), Ford Endura (Ka 1.0), Honda Fit 1.4 i-DSI, and Honda CR-V R20A. These require periodic valve-clearance adjustment.
- Rocker arm with a hydraulic lifter — common in newer engines; it adjusts clearance automatically. No adjustment is needed, but it can tap when cold if the lifter is worn.
What does the rocker arm do?
Without a rocker arm, the valve will not open at the right time, and the engine loses compression and power. When a rocker arm starts to fail, three classic symptoms appear:
- A light, rhythmic metallic tapping in the cylinder head, synchronized with engine speed (do not confuse it with crankshaft knock, which is more serious and comes from the bottom end)
- Loss of power and rough idle — the check-engine light may come on
- Increased fuel and oil consumption
When should you replace or adjust the rocker arm?
Every engine has its own schedule. Valve-clearance adjustment is preventive maintenance — you do not replace anything, just adjust it. Replace the entire rocker arm only when there is mechanical wear (a worn contact surface, stripped adjusting screw, or seized roller).
On engines that do not have hydraulic lifters, periodic adjustment keeps the engine healthy. That is why the channel has detailed procedures for all those cars.
Step-by-step procedures on the channel
Each link below opens the full valve-clearance adjustment procedure, with torque values, feeler-gauge measurements, and a channel video:
- Honda Fit 1.4 (L13A) — intake 0,15-0,19 mm / exhaust 0,26-0,30 mm
- Honda CR-V 2.0 (R20A) — intake 0,18-0,22 mm / exhaust 0,23-0,27 mm
- Ford Ka 1.0 (Endura) — intake 0,20 mm / exhaust 0,50 mm
- VW Brasília 1600 (air-cooled engine) — intake and exhaust 0,10 mm
Endura engine rocker arms — dedicated video
In the Ford Ka Endura engine rebuild series, Paulo devoted an entire episode to the rocker arms — disassembly, wear inspection, and reassembly with the correct torque:
When should you see a mechanic?
Valve-clearance adjustment is a straightforward DIY job with a feeler gauge and the right wrench — the channel shows every step. But replacing a rocker arm, camshaft, or cylinder head requires controlled torque in a specific sequence and wear measurements. If the tapping continues after adjustment, or if there is emulsified oil in the cylinder head, take it to a mechanic you trust.