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Toyota Land Cruiser 4.6L Engine Repair Information

Here you can find information regarding the assembly of the Toyota 4.6L 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 4.6L 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 for the inside bolts and 20 ft-lbs for the outside bolts and then for the third time you do an additional 90 degree turn for each bolt. The bolts on the side of the engine block for the main bearings get torqued down to 20 ft-lbs and then 33 ft-lbs. Once finished you should be good to continue with the rest of the engine.

Toyota Land Cruiser 4.6L Main Cap Torque Specs (Inside) : 45 ft-lbs + 90°

Toyota Land Cruiser 4.6L Main Cap Torque Specs (Outside) : 20 ft-lbs + 90°

Toyota Land Cruiser 4.6L Main Cap Torque Specs (Side) : 33 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 30 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 Land Cruiser 4.6L Connecting Rod Torque Specs : 30 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 pump cover can then be installed onto the oil pump and tighten down to 7 ft-lbs. The oil pickup tube on this engine then bolts up to the bottom of the engine block through the use of 2 nuts. These nuts can be tightened down to 7 ft-lbs.

Toyota Land Cruiser 4.6L Oil Pump Torque Specs : 8 ft-lbs

Toyota Land Cruiser 4.6L Oil Pump Cover Torque Spec: 7 ft-lbs

Toyota Land Cruiser 4.6L Oil Pickup Tube Torque Specs : 7 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 4.6L starts off with 25 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 smaller bolts for the cylinder head that have a 12mm bolt head can be torqued down to 15 ft-lbs. After torquing the heads are completely installed and you can now move to intalling the timing.

Toyota Land Cruiser 4.6L Cylinder Head Torque Specs : 27 ft-lbs + 90° + 90°

Toyota Land Cruiser 4.6L Cylinder Head Torque Specs (12 mm) : 15 ft-lbs

 

Timing Chain and Tensioner Installation

On the Toyota 4.6 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, 2 chain tensioners, a crankshaft pulley, and 2 chain guides. Before installing the chain itself make sure all of the components are tight and torqued properly. The camshaft timing tube sprockets get tightened to 74 ft-lbs, the tensioners get tightened down to 17 ft-lbs and the guides get tightened down to 10 ft-lbs. The timing camshaft chain system that is isolated within the heads has a chain that runs from one camshaft to the other. The chains tensioner gets tightened down to 17 ft-lbs while the chains guides get tightened down to 15 ft-lbs. The chains should be installed using the timing marks on the chain and sprockets. New chains come with imagery for this installation. The camshafts are held down to the cylinder head by camshaft bearing caps which should be tightened to 12 ft-lbs and 22 ft-lbs for the bolts directly over the timing tubes. The crankshaft timing sprocket merely gets placed onto the shaft and aligned using a woodruff key. With the sprockets all in place and the number 1 cylinder in TDC or top dead center you can then install the timing chain onto each sprocket by aligning the painted marks with the dots on each sprocket. The left side chain should be installed first followed by the right side. Be sure to have the timing correct as this is a crucial part of the engine. Once the marks are lined up you can detension the tensioners which will hold the chains in place. From here you can move onto the timing cover. The crankshaft position sensor should either be already installed or installed now and torqued down to 8 ft-lbs.

Toyota Land Cruiser Camshaft Sprocket Torque Spec: 74 ft-lbs

Toyota Land Cruiser Crankshaft Position Sensor Torque Spec: 8 ft-lbs

Toyota Land Cruiser Camshaft Bearing Caps Torque Spec : 12 ft-lbs

Toyota Land Cruiser Camshaft Bearing Cap No1 Torque Spec : 22 ft-lbs

Toyota Land Cruiser Timing Chain Tensioner Torque Spec : 17 ft-lbs

Toyota Land Cruiser Timing Chain Guides Torque Spec : 10 ft-lbs

Toyota Land Cruiser Camshaft Timing Chain Tensioners Torque Spec : 17 ft-lbs

Toyota Land Cruiser Camshaft Timing Chain Guides Torque Spec : 15 ft-lbs

 

Timing Cover Installation

The timing cover on the 4.6L is used to cover up the timing chain and to keep engine oil inside of the engine. For this reason I recommend using a new gaskets and or silicon sealant during the installation of this part. Make sure that both contact surfaces are clean and ready before installing. Once ready you can place the timing cover onto the engine and begin to hand tighten the bolts. Be sure to follow your gasket or sealant manufacturers specifications. There are 2 different sized cover bolts on this engine, the larger bolts need to be torqued down to 35 ft-lbs while the smaller bolts need to be torqued down to 17 ft-lbs. Be sure to check the sizes before torqueing.

Toyota Land Cruiser Timing Cover Torque Specs (large) : 35 ft-lbs

Toyota Land Cruiser Timing Cover Torque Specs (small) : 17 ft-lbs

 

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Oil Pan Installation

On the 4.6L 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. On the 4.6L there is an upper and lower oil pan. On the upper pan there are 2 different sizes of oil pan bolts being 10mm and 12mm bolt heads. The 10mm bolts get tightened down to 7 ft-lbs while the 12mm ones get tightened down to 26 ft-lbs. On the lower oil pan the bolts get tightened down to 7 ft-lbs. 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 Land Cruiser Upper Oil Pan Torque Specs (10mm): 7 ft-lbs

Toyota Land Cruiser Upper Oil Pan Torque Specs (12mm): 26 ft-lbs

Toyota Land Cruiser Lower Oil Pan Torque Specs : 7 ft-lbs

Toyota Land Cruiser 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 Land Cruiser 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 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 15 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. The fuel inlet pipe can be tightened down to 22 ft-lbs.

Toyota Land Cruiser Intake Manifold Torque Specs : 15 ft-lbs

Toyota Land Cruiser Ignition Coil Torque Specs : 5 ft-lbs

Toyota Land Cruiser Spark Plug Torque Specs : 15 ft-lbs

Toyota Land Cruiser Fuel Rail Torque Specs : 8 ft-lbs

Toyota Land Cruiser Fuel Inlet Pipe Torque Specs : 22 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 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 Land Cruiser Exhaust Manifold Torque Spec : 15 ft-lbs

Toyota Land Cruiser Exhaust Pipe Torque Specs : 30 ft-lbs

Toyota Land Cruiser EGR Pipe Torque Specs : 14 ft-lbs

 

Water Pump and Thermostat Installation

The water pump on the Toyota 4.6L 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 should be torqued to 14 ft-lbs. The water pump pulley can be torqued to the water pump itself with 14 ft-lbs.

Toyota Land Cruiser Water Pump Torque Specs : 14 ft-lbs

Toyota Land Cruiser Water Pump Pulley Torque Specs : 14 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 with them. For the belt system the crankshaft pulley gets torqued to 221 ft-lbs. The belt tensioner can be tightened to 17 ft-lbs and the idler pulley can be torqued down to 32 ft-lbs as well. 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 14 ft-lbs.

Toyota Land Cruiser Crankshaft Pulley Torque Specs : 221 ft-lbs

Toyota Land Cruiser Idler Pulley Bolt Torque Spec : 32 ft-lbs

Toyota Land Cruiser Belt Tensioner Torque Specs : 17 ft-lbs

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

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

Toyota Land Cruiser Power Steering to Head Torque Specs : 14 ft-lbs

Toyota Land Cruiser Power Steering to Bracket Torque Specs : 30 ft-lbs