Unit Repair

Engine Component Description

Engine Construction
The engine is a four cylinder in-line, four stroke gasoline unit with a Double Overhead Cam (DOHC) valve mechanism arranged for V-type valve configuration.
The DOHC is mounted over the cylinder head and is driven by the crankshaft through TWC timing chains. In this configuration there are no push rods and no rocker arms provided in the valve train system.

Cylinder Block
The cylinder block is an aluminum casting with four cast iron cylinder sleeves. The cylinder block has four in-line cylinders, which are numbered 1 through 4 starting from the crankshaft pulley. The cylinder block contains coolant jackets through which coolant flows around the cylinders, to cool the cylinder block and maintain a constant operating temperature. The lower crankcase of the cylinder block is also an aluminum casting with cast iron inserts at the main bearing locations. The lower crankcase runs the entire perimeter of the cylinder block.

Crankshaft
The crankshaft is nodular cast iron and is supported by five main bearings. The crankpins of cylinders 1 and 4 are 180 degrees from the crankpins of cylinders 2 and 3. The crankshaft is counterbalanced by the flywheel, the crankshaft balancer and eight counterweights cast into the crankshaft. Oil holes run through the center of the crankshaft to supply oil to the connecting rods, bearings, pistons and other components. The end thrust load is taken by the thrust washers installed at the center number three bearing journal. The main bearings are of the precision insert type. The front of the crankshaft incorporates a sprocket, which drives the oil pump through a sprocket and chain.

Connecting Rod and Piston
Each piston is cast aluminum alloy and has TWC compression rings and one oil ring. The piston rings are of a low tension type to reduce friction. The top compression ring is plated with chromium for abrasion resistance. The second compression ring is gray iron. The oil ring is a 3-piece spring construction, consisting of TWC rails and one spacer.
The piston pin is offset 0.5 mm (0.02 inch) toward the thrust side. This allows a gradual change in thrust pressure against the cylinder wall as the piston travels through the bore. The connecting rods are forged steel, heat treated and shot peened. Piston pins are chromium steel and have a full floating fit in the pistons and in the connecting rods. The connecting rod bearings are of the precision insert type.

Oil Pump
The oil pump is bolted to the bottom of the lower crankcase. A sprocket on the front of the oil pump is driven by a chain from the sprocket on the front of the crankshaft. The tension on the oil pump drive chain is accomplished by an adjustable guide.

Oil Pan
The oil pan is constructed of stamped steel and is mounted to the lower crankcase. The oil pan includes a baffle that helps prevent the oil from shifting away from the oil pump suction pipe during hard turns, acceleration or stopping.

Cylinder Head
The cylinder head is an aluminum alloy casting with pressed-in valve guides and valve seat inserts. The fuel injection nozzles are located in the intake ports.
The cylinder head has four in-line combustion chambers. Each combustion chamber has TWC intake valves and TWC exhaust valves.
A fuel injector is positioned near each set of intake valves. During each intake stroke of the engine, a fuel injector sprays or atomizes fuel into a fine mist. This mist mixes with air drawn in through the intake manifold as the piston reaches the bottom of the cylinder during the intake stroke.

Valves
The valve train is driven by a double overhead camshaft. Each camshaft has eight cam lobes. Each cam lobe operates an intake or exhaust valve. Valve lash is not adjustable. Valve Lash is provided for by Hydraulic Valve Lash (HVL) Adjusters.
There are TWC intake and TWC exhaust valves per cylinder. There are TWC valve springs per valve. The valve springs are conical-shaped to fit inside the valve lifter body. Positive valve stem seals are used on all valves.

Valve Lifters
Direct acting hydraulic valve lifters are used. The valve lifter body includes a hardened iron contact foot bonded to a steel shell. These lifters are not repairable.

Valve Lifter (Hydraulic Valve Lash Adjuster) Operation





The Hydraulic Valve Lash (HVL) Adjuster located between the camshaft and the valve stem is a direct acting type.
With the engine oil delivered into it from the oil pump, the HVL adjuster operates as follows to adjust the valve lash (clearance) to 0 automatically at all times.
1. When the camshaft is not depressing the HVL adjuster, the adjuster is held against the camshaft and the valve stem by the plunger spring. In this state, the valve lash is kept at 0. (At 0 valve lash, the oil pressure becomes equal in the A (1) and B (2) chambers, and the check ball closes the passage between these TWC chambers.
2. When the lobe of the camshaft starts pressing the HVL adjuster, the adjuster and plunger are pushed downward at the same time the body is pushed upward by the counterforce from the valve stem. As a result, the B (2) chamber is compressed and the pressure rises inside the HVL adjuster. The engine oil in the B (2) chamber will leak through the slight clearance between the body and the plunger. However, since the compression time is very short, the volume of engine oil in the B (2) chamber will only change slightly and the HVL adjuster (plunger and body as one unit) push down the valve stem to open the valve.
3. When the pushing of the camshaft against the HVL adjuster is over, the operation starts again as described in step 1. As the oil pressure in the B (2) chamber is lower than that in A (1) (the oil in the B (2) chamber under high pressure has leaked gradually-refer to step 2), the oil pressure in the A (1) chamber pushes the check ball open to allow the engine oil to flow from the A (1) chamber to the B (2) chamber until the oil pressure becomes equal between the TWC chambers.

Camshaft
TWC camshafts are used, one for all intake valves, the other for all exhaust valves. The camshafts are cast iron. The exhaust camshaft rear end is slotted to mate with, and drive the camshaft position sensor.

Camshaft Housings and Caps
The camshaft housings and caps are cast aluminum. The camshafts run directly on the housings and caps without bearing inserts.

Camshaft Drive
TWC roller timing chains are used. One chain is driven from the crankshaft and drives an idler gear. A second chain is driven from the idler gear and drives the camshafts.
A mechanical, ratcheting tensioner applies tension to an adjustable guide on the slack side of the crankshaft timing chain. A fixed guide controls crankshaft chain motion on the tension side of the chain.
An hydraulic tensioner and an upper guide control camshaft chain motion. The hydraulic tensioner incorporates a guide, which applies tension to the slack side of the camshaft timing chain.

Timing Chain Housing and Cover
The timing chain housing is die cast aluminum and retains the crankshaft front seal.

Cylinder Head Cover
The cylinder head cover is die cast aluminum and houses the ignition coils.

Intake and Exhaust Manifold
The intake manifold is made of aluminum. The exhaust manifold is cast iron.

Lubrication Description
The oil pump is of a trochoid type, and is mounted under the crankshaft. Oil is drawn up through the oil pump strainer and passed through the pump to the oil filter. The filtered oil flows into 2 paths in the cylinder block. In one path, the oil reaches the crankshaft journal bearings. Oil from the crankshaft journal bearings is supplied to the connecting rod bearings by means of intersecting passages drilled in the crankshaft, and then injected from the big end of the connecting rod to lubricate the piston, rings, and cylinder wall.
In other paths oil goes up to the cylinder head and lubricates valves and camshafts after passing through he internal oilway of camshafts.
An oil relief valve is provided on the oil pump. This valve starts relieving oil pressure when the pressure exceeds about 420 kPa (59.7 psi).

Cleanliness and Care
An automobile engine is a combination of many machined, honed, polished, and lapped surfaces with tolerances that are measured in ten thousandths of an inch. When any internal engine parts are serviced, care and cleanliness are important. A liberal coating of engine oil should be applied to friction areas during assembly to protect and lubricate the surfaces during initial operation. It should be understood that proper cleaning and protection of machined surfaces and friction areas are part of the repair procedure. This is considered standard shop practice even if not specifically stated.
When valve train components are removed for service, they should be retained in order. At the time of installation, they should be installed in the same locations and with the same mating surfaces as when removed.

Replacing Engine Gaskets
- Tools Required
- J 28410 Gasket Remover (Aluminum)

Gasket Reuse and Applying Sealants
- Do not reuse any gasket unless specified.
- Gaskets that can be reused will be identified in the service procedure.
- Do not apply sealant to any gasket or sealing surface unless called out in the service information.

Separating Components
- Use the proper prying points to separate components.
- Use caution when separating all RTV sealed components.

Cleaning Gasket Surfaces
- Remove all gasket and sealing material from the part using the J28410
- Care must be used to avoid gouging or scraping the sealing surfaces.
- Do not use any other method or technique to remove sealant or gasket material from a part.
- Do not use abrasive pads, sand paper, or power tools to clean the gasket surfaces.
- These methods of cleaning can cause damage to the component sealing surfaces.
- Abrasive pads also produce a fine grit that the oil filter cannot remove from the oil.
- This grit is abrasive and has been known to cause internal engine damage.

Assembling Components
- When assembling components, use only the sealant specified or equivalent in the service procedure.
- Sealing surfaces should be clean and free of debris or oil.
- Specific components such as crankshaft oil seals or valve stem oil seals may require lubrication during assembly.
- Components requiring lubrication will be identified in the service procedure.
- When applying sealant to a component, apply the amount specified in the service procedure.
- Do not allow the sealant to enter into any blind threaded holes, as it may prevent the bolt from clamping properly or cause component damage when tightened.
- Tighten bolts to specifications. Do not overtighten.

Use of RTV and Anaerobic Sealer
The following 2 types of sealer are commonly used in engines:
- The RTV sealer
- The anaerobic gasket eliminator sealer
Follow the service procedure instructions. Use the correct sealer in the proper place in order to prevent oil leaks. Do not interchange the 2 types of sealers. Use the sealer recommended in the service procedure.

Applying RTV Sealer
- Do not use the room temperature vulcanizing (RTV) sealant in areas where extreme temperatures are expected. These areas include the following locations:
- The exhaust manifold
- The head gasket
- The other surfaces where gasket eliminator is specified
- Use a rubber mallet in order to separate the components sealed with RTV sealant. Bump the part sideways in order to shear the RTV sealer. Perform the bumping at the bends or the reinforced areas in order to prevent distortion of the components. The RTV sealant is weaker in shear (lateral) strength than in tensile (vertical) strength.

Important: Do not use any other method or technique in order to remove the gasket material from a component.

- Do not use the following items in order to clean the gasket surfaces:
- Abrasive pads
- Sand Paper
- Power tools
These methods of cleaning may damage the part.
Abrasive pads also produce a fine grit that the oil filter cannot remove from the oil. This grit is abrasive and may cause internal engine damage.
- Remove all of the gasket material from the component using a plastic or a wood scraper. Use Loctite brand gasket remover P/N 4MA or the equivalent. Follow all of the safety recommendations and the directions that are on the container.

Important: Do not allow the sealer to enter the blind threaded holes. The sealer may cause the following conditions:

- Prevent you from properly seating the bolt
- Cause damage when you tighten the bolt
- Apply the RTV sealant to a clean surface. Use a bead size as specified in the procedure. Apply the bead to the inside of any bolt holes.
- Assemble the components while the RTV sealant is still wet (within 3 minutes). Do not wait for the RTV sealant to skin over.

Important: Do not overtighten the bolts.

- Tighten the bolts to specifications.

Applying Anaerobic Sealer
The anaerobic gasket eliminator hardens in the absence of air. This type of sealer is used where 2 rigid parts (such as castings) are assembled together. When 2 rigid parts are disassembled and no sealer or gasket is readily noticeable, the parts were probably assembled using a gasket eliminator.

Important: Do not use any other method or technique in order to remove the gasket material from a component.

Do not use the following items in order to clean the gasket surfaces:
- Abrasive pads
- Sand paper
- Power tools
These methods of cleaning may damage the part.
Abrasive pads also produce a fine grit that the oil filter cannot remove from the oil. This grit is abrasive and may cause internal engine damage.
- Remove all of the gasket material from the component using a plastic or a wood scraper. Use Loctite brand gasket remover P/N 4MA or the equivalent. Follow all of the safety recommendations and the directions that are on the container.
- Apply a continuous bead of the gasket eliminator to 1 flange. Clean and dry any surfaces that you will reseal.

Important: Anaerobic sealed joints that are partially torqued and allowed to cure more than 5 minutes may result in incorrect shimming and sealing of the joint.

- Do not allow the sealer to enter the blind threaded holes. The sealer may cause the following conditions:
- Prevent you from properly seating the bolt
- Cause damage when you tighten the bolt
- Spread the sealer evenly in order to get a uniform coating on the sealing surface.
- Tighten the bolts to the specifications.
- Remove the excess sealer from the outside of the joint.

Separating Parts

Important: Many internal engine components will develop specific wear patterns on their friction surfaces.

When disassembling the engine, internal components MUST be separated, marked, or organized in a way to ensure reinstallation to their original location and position.
Separate, mark, or organize the following components:
- Piston and the piston pin
- Piston to the specific cylinder bore
- Piston rings to the piston
- Connecting rod to the crankshaft journal
- Connecting rod to the bearing cap
A paint stick or etching/engraving type tool are recommended. Stamping the connecting rod or cap near the bearing bore may affect component geometry.
- Crankshaft main and connecting rod bearings
- Camshaft and valve lifters
- Valve lifters, lifter guides, pushrods and rocker arm assemblies
- Valve to the valve guide
- Valve spring and shim to the cylinder head location
- Engine block main bearing cap location and direction
- Oil pump drive and driven gears

Tools and Equipment
Special tools (or their equivalents) are specially designed to quickly, and safely accomplish the operations for which they are intended. The use of these special tools will also minimize possible damage to engine components. Some precision measuring tools are required for inspection of certain critical components. Torque wrenches and a torque angle meter are necessary for the proper tightening of various fasteners.
To properly service the engine assembly, the following items should be readily available:
- Approved eye protection and safety gloves
- A clean, well-lit, work area
- A suitable parts cleaning tank
- A compressed air supply
- Trays or storage containers to keep parts and fasteners organized
- An adequate set of hand tools
- Approved engine repair stand
- An approved engine lifting device that will adequately support the weight of the components