Toyota 13801-23011 Arm Sub-Assembly, Valve Rocker

To take off the valve cover, first, you need to unscrew the timing chain guide from the top of the timing chain area and pull off the O-ring underneath it. The engine needs to be set to TDC on the compression stroke, then align the timing marks that are seen on the camshaft sprockets to those of the camshaft front bearing caps, one must make a mark on the stated links of the chain. Disconnect the plug from the right side of the timing chain cover, and use flat blade screw driver and rotate the tensioner stopper plate unlock the tensioner by pushing the plunger in. Rotate the stopper plate up and by turning the exhaust camshaft a little clockwise to compress the plunger, and then insert the steel pin into the stopper plate hole. Take off the exhaust camshaft sprocket bolt and pull out the sprocket, along with the removal of the camshaft bearing cap bolts, but in an opposite sequence as to how they were tightened. Afterwards, take off the oil tube and its rubber O-ring and then the front camshaft bearing cap followed by the other bearing caps to extract the camshafts out with tension on the chain. Pull the timing chain upwards and lock it to prevent the chain from falling to the timing chain cover, additionally, if necessary, remove all the rocker arms and the lash adjusters, and mark all the components which should be reattached. Place the intake camshaft on the bench in such a way that the timing gear should not be able to rotate, then, thereafter, take off the center intake camshaft sprocket bolt. Check each rocker arm for wear and damage paying attention to each roller that must spin freely and inspect the lash adjuster for signs of damage, replacing any damaged lash adjusters. Cam lobes and bearing journals should also be checked for signs of wear or overheating and if the height of each camshaft lobe and the diameter of each journal does not conform to the factory set parameters, they should be replaced. To check the oil clearance of each camshaft journal, it will be done with the help of Plastigage and the width of the crushed material should be within the limit. On installation, ensure the intake camshaft sprocket has engaged the knock pin and torque the bolt; apply oil on the lobes and bearing journals of both camshafts. Position and properly seat each of the lash adjuster and rocker arm and then fit the intake camshaft with sprocket mark upwards, engaged with the timing chain, and the paint mark aligned. Place the exhaust camshaft without sprocket followed by assembling the front camshaft bearing cap together with the bolts, tighten them only in this manner and the other caps in a progressive way. Retorque the bearing cap bolts to specification by turning them in the opposite direction in increments of ninety degrees till you achieve the necessary torque weight, fit the timing chain around the exhaust camshaft sprocket and screw the sprocket up to the camshaft. Ensure that all the corresponding timing marks are in the appropriate positions then, through the tensioner, the pin of the crankshaft pulley must be released and the hole of the tensioner duly fitted using the tensioner hole plug along with a sealant. Screw in the crankshaft pulley bolt and try to rotate the engine clockwise with the key till the camshafts and the chain are correctly positioned; do not force the engine if resistance is met. Lastly, reverse the manner and replace such items as the O-rings for the guide of the timing chain and the tube for oil, if necessary.

The manufacturer recommends removing the engine and transaxle assembly before starting this procedure. This procedure is not recommended for beginners or those with limited experience.

The initial steps involve draining the engine oil and coolant, followed by the removal of the timing chains and sprockets.

Inspect each rocker and lash adjuster arm for wear.

Apply a dab of paint to the timing chain links where they meet the upper timing marks on the camshaft sprockets.

Carefully pry the camshaft housing from the top of the cylinder head.

Disconnect the cable from the negative terminal of the battery.