Acura engine rattle at cold start

This bulletin involves 2009 Acura YSX L4 and 2010 Acura TSX L4 from VIN JH4CU2....AC000001 through JH4CU2....AC027068. At cold start-up, the engine rattles loudly for about two seconds.

The probable cause: the variable valve timing control (VTC) actuator is defective.

Replacing the VTC does not require the complete removal of the cam chain and associated parts.

The replacement VTC is available as P/N 14310-R40-A01. Required materials include Hondabond HY liquid silicone gasket, P/N 08718-0004 (one tube is enough for two vehicle repairs). Required tools include a stopper (lock pin), P/N 14511-PNA-003, tappet adjuster P/N 07MAA-PR70110 and tappet locknut wrench P/N 07MAA-PR70120.


Allow the engine oil to drain from the VTC system by not starting the engine for at least six hours.

Start the engine. If you hear a loud rattle that lasts about two seconds, continue with the repair.

Remove the ignition coil cover and coils. Remove the engine oil dipstick and power steering hose bracket. Disconnect the breather hose and the brake booster vacuum hose from the cylinder head cover. Remove the two bolts holding the EVAP canister purge valve bracket to the cylinder head. Remove the cylinder head cover.

Raise the vehicle on a lift and turn the front wheels or remove the right front wheel. Remove the splash shield to access the crank pulley. Remove the camshaft auto-tensioner (chain case) cover.

Rotate the crankshaft clockwise to bring No. 1 piston to top dead center (TDC).

Rotate the crankshaft counterclockwise to compress the auto tensioner, then align the hole in the lock and auto tensioner, and insert a 1.2 mm stopper (lock pin).

Rotate the crankshaft clockwise to No. 1 TDC. Lower the vehicle.

Mark the cam chain at the punch marks on the exhaust camshaft sprocket and the VTC actuator. Secure the chain to the sprocket with a wire tie.

Hold the camshaft steady with an open-end wrench, and loosen the VTC actuator mounting bolt. Do not use an impact wrench to loosen or tighten this bolt, as this will damage the locking pin inside the actuator.

Loosen the camshaft main cap bolts, in sequence, two turns at a time. Remove the cam main caps.

Carefully tip up the end of the intake camshaft until there is enough slack to lift the chain off of the VTC actuator teeth. Remove the intake camshaft while keeping some tension on the chain. Store the intake camshaft on a clean workbench.

Secure the chain to the A/C compressor hose with a wire tie to keep it from falling down into the front cover.

Remove the VTC actuator mounting bolt and separate the actuator from the camshaft.

Apply clean engine oil to the mounting bolt threads and install the new VTC actuator to the camshaft, finger-tight.

Remove the wire ties while keeping light tension on the chain.

Rotate the VTC actuator clockwise to lock it.

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