Crankshaft, timing and valvetrain

VVT camshaft adjusters

Variable valve timing (VVT) camshaft adjusters: the phasers on the end of the camshaft that turn it against its sprocket under oil pressure, so the engine control unit can advance or retard the valve timing with speed and load, for European and Japanese passenger cars, identified by OE reference.

MONTTRON VVT camshaft adjusters: two variable valve timing phasers with their chain sprockets, one seen from the front and one from the back

A VVT camshaft adjuster, also called a phaser, sits on the end of the camshaft in place of a plain sprocket. Inside it a rotor with vanes, fixed to the camshaft, turns within a housing fixed to the sprocket; engine oil, directed by a solenoid control valve, pushes the vanes one way or the other, so the camshaft turns a few degrees against its drive and the valves open earlier or later. The engine control unit uses this to give more torque at low speed, more power at high speed and lower emissions and consumption in between. A locking pin holds the adjuster at its base position when there is no oil pressure, so the engine starts quietly and in time.

Adjusters wear inside. The locking pin and its seat wear, so the vanes rattle for a moment after every cold start until oil pressure takes over; the vanes and the housing wear, so the adjuster no longer holds the angle the control unit asks for and the engine idles roughly, loses power and logs a camshaft timing fault. Dirty oil and blocked oil ports make all of this worse, which is why the oil condition and the control valve are checked before the adjuster is condemned.

MONTTRON VVT camshaft adjusters are made to OEM-compliant quality and as aftermarket spare parts: the sprocket, the vane geometry, the oil ports and the locking pin of the original, so the adjuster runs on the original chain and answers the original control valve. 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 rattle from the front of the engine at start-up?
Often the adjuster. At start-up the phaser should be held at its base position by a locking pin until oil pressure builds; when the pin or its seat is worn, the vanes knock inside the housing for a second or two after every cold start. The noise goes away as pressure builds, and it comes back the next morning.
Which faults point to the adjuster?
A camshaft position or timing correlation fault code, a rough idle, a loss of power or a rise in fuel consumption, and the start-up rattle. The control valve that feeds the adjuster and the oil condition are checked first, because a sticking valve or dirty oil produces the same codes.

Back to Crankshaft, timing and valvetrain