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Toyota Avalon 3.5L Engine Repair Information

Here you can find information regarding the assembly of the Toyota 3.5L engine. In this guide we will start from the inside of the engine including the crankshaft, connecting rods, and piston ring installation and then move outwards all the way to the pulley belt system. Along the way correct procedures and torque specs will be given to aid in the assembly of the engine. Feel free to start from the beggining and work your way outwards or skip ahead to your current position in the engine for what you may need.

Crankshaft Main Caps Installation

The 3.5L engine block main bearing caps should be inspected for any defects or flaws before installation. Be sure to lubricate the bearing surfaces prior to installation. Once prepared you can place the caps onto the crankshaft and begin tightening the bolts down in a multi stage process. The first being 10 ft-lbs starting from the middle and going outwards. The second time around you can go to 45 ft-lbs and then for the third time you do an additional 90 degree turn for each bolt. Once finished you should be good to continue with the rest of the engine. The side main cap bolts get tightened down to 38 ft-lbs.

Toyota Avalon 3.5L Main Cap Torque Specs : 45 ft-lbs + 90°

Toyota Avalon 3.5L Main Cap Side Bolts Torque Specs : 38 ft-lbs

 

Piston and Connecting Rod Installation

To install the pistons and connecting rods you must first install the piston rings into each piston. Be careful not to stretch the rings or break them during installation. Make sure to put the correct rings in the correct positions, this can be determined by looking at the instructions given with the new rings. Each ring manufacturer is different so be sure to check for your specific rings. Once the rings have been installed you can now fit the connecting rod bearings into the end caps and lube them up with oil or lithium grease. The piston can now be lowered into the cylinder, make sure the dot or mark is facing the front of the engine and that you don't scratch the cylinder. Once installed you can match the connecting rod caps with the correct rods and start to torque the connecting rod bolts to 18 ft-lbs and then an additional 90 degree turn for each bolt. After all are done rotate the crank to ensure all pistons move smoothly in and out of their cylinders and nothing binds.

Toyota Avalon 3.5L Connecting Rod Torque Specs : 18 ft-lbs + 90°

 

Oil Pump Installation

When installing the oil pump be sure to use the proper sealant around the pump base if neccessary to ensure that oil pressure doesn't drop due to leakage. After preparing the contact surfaces carefully install the oil pump mechanics onto the crankshaft by aligning the crankshaft end with the hole on the center of the pump gear. Once installed you can then place the oil pump onto the engine block and tighten down the bolts to 8 ft-lbs. The oil pickup tube on this engine then bolts up to the bottom of the engine block through the use of 2 fasteners. These bolts can be tightened down to 8 ft-lbs. The oil pump relief valve tightens down to the oil pump at 36 ft-lbs.

Toyota Avalon 3.5L Oil Pump Torque Specs : 8 ft-lbs

Toyota Avalon 3.5L Oil Pump Relief Valve Torque Specs : 36 ft-lbs

Toyota Avalon 3.5L Oil Pickup Tube Torque Specs : 8 ft-lbs

 

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Cylinder Head Installation

The first thing you must do when installing cylinder heads is to ensure both the block and head surfaces are completely clean from dust, oil, and any debris. The next thing you must to is to set the camshafts to their correct positions to prevent any valves from hitting pistons during installation and torquing of the head bolts. Much the same you have to set the pistons to their correct locations, typically this means putting the #1 piston to TDC or Top Dead Center. Once everything is ready you can install the head gasket onto the engine block by aligning the alignment dowels. Something I usually do is spray down the head gasket with some engine copper spray from permatex which you can find here, this ensures that any gaps that could be present between the 2 surfaces gets filled with the spray. It also helps to transfer heat between the 2 metals. With the gasket in place you can set the cylinder head onto the gasket and block, if needed have someone assist with this process as the head can be heavy and you don't want to scratch anything or drop it! Once the head has been placed you will want to start installing the head bolts to make sure it doesn't move. Be sure to buy new head bolts as many manufacturers use TTY or Torque to Yield head bolts meaning they stretch during torqueing and cannot be used twice. Also make sure to lubricate the bolts in clean engine oil before installing them into the head. Once all the head bolts have been installed and finger tightened you can start the torqueing process, almost all head bolts have a multi-step process for torqueing. The 3.5L starts off with 20 ft-lbs and then requires you to back them off a full turn. Then you must again torque them to 27 ft-lbs and then a 90 degree turn and finally add another 90 degrees by going through each bolt with each step. The additional cylinder head bolts with 14mm heads get tightened down to 22 ft-lbs. These will be the bolts which do not follow a pattern like the others. They simply are on the edge of the head. After torquing the heads are completely installed and you can now move to intalling the timing.

Toyota Avalon 3.5L Cylinder Head Torque Specs : 27 ft-lbs + 90° + 90°

Toyota Avalon 3.5L Cylinder Head Extra Bolts Torque Specs (14mm): 22 ft-lbs

 

Timing Chain and Tensioner Installation

On the Toyota 3.5 engine the timing system is ran by the use of a timing chain. This chain system consists of a sprocket on a single camshaft per head, a tensioner guide, a crankshaft sprocket, and an idler sprocket between the heads. Before installing the chain itself make sure all of the components are tight and torqued properly. The camshaft sprockets get tightened to 74 ft-lbs, while the idler gear gets tightened down to 44 ft-lbs. The camshafts are held down to the cylinder head by camshaft bearing caps which should be tightened to 8 ft-lbs. The No1 camshaft bearing cap should be torqued down to 18 ft-lbs. This is the one that is biggest and closer to the timing chain system. The timing chain guides and tensioer all get torqued down to 14 ft-lbs but this will occur after the chain has been placed onto the sprockets. The crankshaft timing sprocket merely gets placed onto the shaft and aligned using a woodruf key. With the sprockets all in place and the number 1 cylinder in TDC or top dead center you can then install the timing belt being sure to align the timing marks as shown in the picture. Finally the crankshaft position sensor can be placed into its location and tightened down to 8 ft-lbs.

Toyota Avalon Camshaft Sprockets Torque Spec: 74 ft-lbs

Toyota Avalon Crankshaft Position Sensor Torque Spec: 8 ft-lbs

Toyota Avalon Camshaft Bearing Caps Torque Spec : 12 ft-lbs

Toyota Avalon Camshaft Bearing Cap No1 Torque Spec : 18 ft-lbs

Toyota Avalon Timing Chain Idler Gear Torque Spec : 44 ft-lbs

Toyota Avalon Timing Chain Guides Torque Spec : 14 ft-lbs

Toyota Avalon Timing Chain Tensioner Torque Spec : 14 ft-lbs

 

Timing Cover Installation

The timing cover on the 3.5L is used to cover up the timing chain components and to maintain the engine oil inside of the engine. Since we do not want to have any leaks here I recommend using a new gasket along with some silicon sealant to ensure that a leak does not occur later on. Be sure that both contact surfaces are cleaned properly and preped according to you sealants or gasket manufacturers specs. Once everything is ready you can place the timing cover onto the engine and begin to torque down the timing cover bolts to 15 ft-lbs.

Toyota Avalon Timing Cover Torque Specs : 15 ft-lbs

 

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Oil Pan Installation

Much like the timing cover on the 3.5L the oil pan plays an important role in keeping the engine oil inside the engine. For this reason I recommend using a new gasket as well as some silicone sealant during installation. Using the same technique as before with the cover you clean the surfaces of both the oil pan and the engine block and then install the new gasket onto the block and then follow it up with some silicone sealant. Be sure to follow your sealants instructions to ensure you get the best seal from your application. There are 2 different sized oil pan bolts on this engine. The smaller of the 2 needs to be torque to 7 ft-lbs in a cross pattern design. The larger bolts can be tightened down to 15 ft-lbs in a similar pattern. Along with the pan is the oil pan drain plug, this gets removed and reinstalled quite frequently and can be torqued down to 27 ft-lbs.

Toyota Avalon Oil Pan Torque Specs (10 mm) : 7 ft-lbs

Toyota Avalon Oil Pan Torque Specs (12 mm) : 15 ft-lbs

Toyota Avalon Oil Drain Plug Torque Specs : 27 ft-lbs

 

Valve Covers Installation

The valve cover installation is rather simple, there are rubber seals for each bolt hole and a silicone gasket that prevents oil from leaking out of the engine. It is recommended to replace both the seals and the gaskets although if they are in good condition you can reuse them. If you do choose to reuse them I would use some silicone sealant along with the silicon gasket to ensure it does not leak. The valve cover bolts torque down to 106 in-lbs or about 8 ft-lbs in a criss cross order. Be sure not to miss any bolts to avoid having oil leak out onto the exhaust pipes and cause a lot of smoking.

Toyota Avalon Valve Cover Torque Specs : 8 ft-lbs

 

Intake Manifold and Fuel Rail Installation

When installing the intake manifold you want to make sure you have all the surfaces as well as intake holes cleaned out before placing the manifold into position. Once cleaned you can then place the intake manifold gaskets onto the alignment pins. If you want you can also use a little bit of sealant on the gaskets to help ensure there are no leaks. With the gaskets in place you can now put the manifold down onto the gaskets and begin to install the bolts. The intake manifold bolts torque to 15 ft-lbs and can be tightened starting from the inside and going outwards. The air surge tank that bolts onto the intake manifold can then be installed and torqued down to 21 ft-lbs. The COPs or the coils for the spark plugs get torqued down to 60 in-lbs or about 5 ft-lbs and the spark plugs themselves can be torqued down to 13 ft-lbs, be careful not to overtorque these as they can snap and cause big problems. When installing the fuel rail make sure that all the fuel injectors are in good condition and that all the o-rings are in place and are in good condition. If everything is good you can place the fuel rail into position and push the injectors into their holes and start to torque the rail bolts to 90 in-lbs or about 8 ft-lbs.

Toyota Avalon Intake Manifold Torque Specs : 15 ft-lbs

Toyota Avalon Intake Surge Tank Torque Specs : 21 ft-lbs

Toyota Avalon Ignition Coil Torque Specs : 5 ft-lbs

Toyota Avalon Spark Plug Torque Specs : 13 ft-lbs

Toyota Avalon Fuel Rail Torque Specs : 8 ft-lbs

 

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Exhaust Manifold Installation

The exhaust manifold can be installed by cleaning the surface areas on both the head an the manifold itself and then by using the exhaust manifold gasket and putting it in place. Once the gasket is in its location you can put the manifold onto the heads and begin to torque the nuts down to 15 ft-lbs. I always use some copper spray from permatex on the exhaust manifold gaskets to ensure I do not end up with any exhaust leaks once done. When you go to install the engine into the vehicle or if it is already in the vehicle the torque specs for the exhaust manifold to the exhaust pipes or catalytic converter and exhaust pipe stay is 30 ft-lbs. The EGR system consists of a series of pipes that range from the manifold to the head. All of the EGR pipes can be tightened down to 14 ft-lbs.

Toyota Avalon Exhaust Manifold Torque Spec : 15 ft-lbs

Toyota Avalon Exhaust Pipe Torque Specs : 30 ft-lbs

Toyota Avalon EGR Pipe Torque Specs : 14 ft-lbs

 

Water Pump and Thermostat Installation

The water pump on the Toyota 3.5L engine should be installed by using a new gasket and if desired some silicon sealant to help prevent leaks. Be sure to clean both metal surfaces prior to installing the pump. Once prepared the pump can be moved into placed and the bolts can be installed and torqued. This engines water pump bolts can be torqued down to 8 ft-lbs on the timing cover. The larger bolts can be torqued down to 15 ft-lbs. The water pump pulley can be torqued to the water pump itself with 15 ft-lbs.

Toyota Avalon Water Pump Torque Specs (10 mm) : 8 ft-lbs

Toyota Avalon Water Pump Torque Specs (12 mm) : 15 ft-lbs

Toyota Avalon Water Pump Pulley Torque Specs : 15 ft-lbs

 

Front Dress and Pulley belt Installation

Most of what is left on the engine is just place and tighten objects such as the belt pulleys, belt tensioner, throttle body, oil filter neck, crankshaft pulley, and motor mounts. If the items have a gasket and hold either oil or coolant inside the engine then feel free to add some sealant along with the gasket. Always be sure to inspect your gaskets and replace them if there is any deteriation or flaws within them. For the belt system the crankshaft pulley gets torqued to 185 ft-lbs. The belt tensioner can be tightened to 27 ft-lbs and the idler pulley can be torqued down to 30 ft-lbs. When installing be sure they both turn smoothly and if they do not then replace them with new ones as the bearings can go bad. The engine motor mount can be installed onto the engine block if it hasn't been already, the torques for the mount to the block is 59 ft-lbs and then when installing the mount to the vehicle or frame it can be torqued to 35 ft-lbs. Finally the throttle body can be installed on top of the intake manifold with a good gasket and some added sealant using 7 ft-lbs in a criss cross pattern. For installing the belt you can use a tool to move the tensioner into its springed state and install the belt as shown in the picture. The power steering pump pulley should be tightened down to the engine at 30 ft-lbs.

Toyota Avalon Crankshaft Pulley Torque Specs : 185 ft-lbs

Toyota Avalon Idler Pulley Bolt Torque Spec : 30 ft-lbs

Toyota Avalon Belt Tensioner Torque Specs : 27 ft-lbs

Toyota Avalon Motor Mount to Engine Torque Specs : 59 ft-lbs

Toyota Avalon Motor Mount to Frame Torque Specs : 35 ft-lbs

Toyota Avalon Power Steering to Engine Torque Specs : 30 ft-lbs

Toyota Avalon A/C Compressor to Engine Torque Specs : 16 ft-lbs

Toyota Avalon Alternator to Engine Torque Specs : 18 ft-lbs