Crankshaft, timing and valvetrain

Rocker arms

Rocker arms that pivot between the camshaft, or the pushrod, and the valve stem and pass the lift of the cam lobe to the valve, with the hardened pad or roller that runs on the lobe and the adjuster or hydraulic element that sets the clearance, for European and Japanese passenger cars, identified by OE reference.

MONTTRON rocker arms: two cast steel rocker arms with their pivot bores, the hardened pads that run on the camshaft and the threaded adjuster ends

The rocker arm sits between the camshaft and the valve. On an overhead-cam engine it pivots on a shaft or a hydraulic pivot, its pad or roller rides on the cam lobe and its other end presses on the valve stem; on a pushrod engine the pushrod lifts one end and the other end opens the valve. The arm’s geometry sets the ratio between the lift of the lobe and the lift of the valve, and an adjuster screw or a hydraulic element at the pivot takes up the clearance in the valvetrain so the valve opens fully and closes quietly.

Rocker arms wear where they touch. The pad wears and pits when the oil film between it and the lobe breaks down, the pivot bush or the roller bearing wears and the arm develops play, and the adjuster or the hydraulic element loses its ability to hold the clearance; the valvetrain then ticks, the valve lift drops and the engine loses power. An arm can break when a valve floats at high speed or when the timing drive fails and a piston strikes an open valve.

MONTTRON rocker arms are made to OEM-compliant quality and as aftermarket spare parts: the pivot bore, the arm ratio, the hardened pad or roller and the adjuster of the original, so the arm runs on the original camshaft and pivot and lifts the original valve by the original amount. The materials are tested for durability and temperature resistance.

The range covers European and Japanese passenger cars. Each reference is identified by the OE number of the original part; send that number and the vehicle identification number (VIN) and we confirm the matching MONTTRON reference.

For availability and OE cross-references, contact us by email.

Frequently asked questions

What is the ticking from the top of the engine?
A gap in the valvetrain. The pad of a rocker arm wears where it runs on the cam lobe, its pivot bush wears, or the adjuster or the hydraulic element no longer takes up the clearance; the lobe then strikes the arm at every cycle. A workshop checks the clearances and the pads before replacing the arms.
Are rocker arms replaced with the camshaft?
Normally yes. A worn pad wears a new cam lobe quickly, so the arms that ran on a worn camshaft are renewed with it, as a set, with new oil and a new filter.

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