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.
Slide the camshaft in at an angle so that the chain can slip over the VTC actuator teeth.
Line up the marks you made on the chain with the punch marks on the exhaust camshaft sprocket and VTC actuator.
Apply clean engine oil to the camshaft journals and cap saddles on both camshafts and reinstall the caps.
Torque the camshaft cap bolts, starting in the center and working your way outward in the numbered sequence. The 8mm x 1.25 bolts must be tightened to a value of 16 ft.-lbs. (22 Nm), and the 6mm x 1.0 bolts are tightened to 8.7 ft.-lbs. (12 Nm).
Hold the camshaft steady with an open-end wrench and torque the VTC actuator mounting bolt to 83 ft.-lbs. (113 Nm). Remove the lock pin from the auto tensioner.
Rotate the crankshaft in the direction of engine rotation (clockwise) two full turns, then stop at the white TDC mark. Make sure that the camshafts are aligned (scribed lines facing each other).
Re-seal and reinstall the chain case cover. Check (and if needed, re-adjust) valve clearance using a tappet adjuster. Intake valve clearance should be 0.008 - 0.010 in. Exhaust valve clearance should be 0.010 - 0.011 in.
Using a tappet locknut wrench, torque the locknuts to a value of 10 ft.-lbs.(14 Nm) at both intake and exhaust locations.
Raise the vehicle, re-install the splash shield, reinstall the right front wheel and lower the vehicle.
Re-install the cylinder head cover (tighten bolts to 8.7 ft.-lbs.(12 Nm). Reinstall the EVAP canister purge valve bracket. Reinstall the engine oil dipstick and power steering hose bracket and reconnect the breather hose a brake booster hose. Reinstall the ignition coils and coil cover. Reinstall the engine cover. Reinstall the frame strut brace, tightening bolts to 16 ft.-lbs.(22 Nm).\
NOTE: Allow at least three hours for the liquid gasket to cure before starting the engine.