Engine Mechanical - 4.3L: Other GMC Savana H2500

Intermittent

Test the vehicle under the same conditions that the customer reported in order to verify the system is operating properly.

Functional Check

With these systems, any blow-by in excess of the system capacity, from a badly worn engine, sustained heavy load, etc., is exhausted into the air cleaner and is drawn into the engine.

Proper operation of the crankcase ventilation system depends upon a sealed engine. If oil slugging or dilution is noted and the crankcase ventilation system is functioning properly, check the engine for a possible cause. Correct any problems.

If an engine is idling rough, check for a clogged crankcase ventilation valve, a dirty vent filter, air cleaner element, or plugged hose. Replace as required. Use the following procedure

1. Remove the crankcase ventilation valve from the rocker arm cover.
2. Operate the engine at idle.
3. Place your thumb over the end of the valve in order to check for a vacuum. If there is no vacuum at the valve, check for the following items: Plugged hoses The manifold port The crankcase ventilation valve
4. Turn OFF the engine. Remove the crankcase ventilation valve. Shake the valve. Listen for the rattle of the check needle inside of the valve. If valve does not rattle, replace the valve.

Honing Procedure

Scheme 699

1. When honing the cylinder bores, follow the manufacturer's recommendations for equipment use, cleaning, and lubrication. Use only clean sharp stones of the proper grade for the amount of material to be removed. Dull, dirty stones cut unevenly and generate excessive heat. DO NOT hone to a final grade with a coarse or medium-grade stone. Leave sufficient metal so that all the stone marks will be removed with the fine grade stones. Perform the final honing with a fine-grade stone and hone the cylinder bore in a cross hatch pattern at 45-65 degrees to obtain the proper clearance.
2. During the honing operation, thoroughly check the cylinder bore. Repeatedly check the cylinder bore fit with the selected piston. All measurements of the piston or cylinder bore should be made with the components at normal room temperature.
3. When honing to eliminate taper in the cylinder bore, use full strokes the complete length of the cylinder bore. Repeatedly check the measurement at the top, the middle, and the bottom of the cylinder bore. The finish marks should be clean but not sharp. The finish marks should be free from imbedded particles or torn or folded metal.
4. When finished, the reconditioned cylinder bores should have less than or meet the specified out-of-round and taper requirements.
5. After the final honing and before the piston is checked for fit, clean the cylinder bore with hot water and detergent. Scrub the cylinder bores with a stiff bristle brush. Rinse the cylinder bores thoroughly with clean hot water. Dry the cylinder bores with a clean rag. Do not allow any abrasive material to remain in the cylinder bores. Abrasive material may cause premature wear of the new piston rings and the cylinder bores. Abrasive material will contaminate the engine oil and may cause premature wear of the bearings.
6. Perform final measurements of the piston and the cylinder bore.
7. Permanently mark the top of the piston for the specified cylinder to which it has been fitted.
8. Apply clean engine oil to each cylinder bore in order to prevent rusting.

Boring Procedure

1. Before starting the honing or reboring operation, measure all the new pistons with the micrometer contacting at points exactly 90 degrees from the piston pin centerline.
2. File the top of the cylinder block in order to remove any dirt or burrs before using any type of boring bar.
3. Follow the instructions furnished by the manufacturer regarding use of the boring equipment.
4. When reboring the cylinders, make sure all the crankshaft bearing caps are installed in the original position and direction.
5. Tighten the crankshaft bearing caps to the proper torque specifications in order to avoid distortion of the cylinder bores in the final assembly.
6. When making the final cut with the boring bar, leave 0.03 mm (0.001 in) on the cylinder bore diameter for finish honing. This gives the required position to the cylinder clearance specifications. Carefully perform the honing and boring operation in order to maintain the specified clearances between the pistons, the piston rings, and the cylinder bores.

Valve Guide Reaming/Valve and Seat Grinding

Tools Required

J 5830-02 Valve Guide Reamer Set

Scheme 700

Scheme 701

Scheme 702

Scheme 703

1. Measure the valve stem-to-guide clearance. Refer to «Cylinder Head Cleaning and Inspection»(ref-158806-S21145876512005031600000) .
2. Improper valve stem (1) to valve guide (2) clearance may cause excessive oil consumption. WARNING: Wear safety glasses in order to avoid eye damage. Important: Exhaust valves with excessive valve stem-to-guide clearance must be replaced with the available service valve that has an 0.774 mm (0.0305 in) oversize valve stem. The intake valves are NOT available with oversize valve stems. Replace the cylinder head if after using a NEW intake valve in order to measure the valve stem-to-guide clearance, the valve stem-to-guide clearance is not within specifications.
3. Use the J 5830-3 in order to ream the exhaust valve guide in order to achieve the correct valve stem-to-guide clearance.
4. Always recondition the exhaust valve seat after reaming the exhaust valve guide bores and installing new exhaust valves.
5. Inspect the valves for the following: Burnt or damaged areas (1) Undersized margin (2) Bent stem (3) Scoring or other damage to the stem (4) Worn key groove (5) Worn stem tip (6)
6. Inspect the valve contact surface for the following: Undersized margin (1) Pitted surface (2) Burnt or eroded areas (3) Acceptable edge margin (4) Valves with excessive damage must be replaced. Minor imperfections of the valve or valve seat may be repaired.
7. Reconditioning of the valves and valve seats: The valves must seat perfectly for the engine to deliver optimum power and performance. Cooling the valve heads is another important factor. Good contact between each valve and valve seat in the cylinder head is necessary to insure that the heat in the valve head is properly carried away. Regardless of what type of equipment is used, it is essential that the valve guide bores are free from carbon or dirt in order to ensure the proper centering of the pilot in the valve guide. The valve seats should be concentric to within 0.05 mm (0.002 in) total indicator reading. Reface pitted valves on a valve refacing machine in order to ensure the correct relationship between the valve head and the valve stem. Replace the valve if the valve stem is excessively worn or warped. Replace the valve if the edge margin (4) of the valve head is less than 0.79 mm (0.031 in) thick after grinding. Several different types of equipment are available for reconditioning valves and valve seats. Follow the equipment manufacturer's recommendations for equipment use to attain the proper results.

Thread Repair

General purpose thread repair kits are available commercially.

Important: Refer to the thread repair kit manufacturer's instructions regarding the size of the drill and which tap to use.

Always avoid any buildup of chips. Back out the tap every few turns and remove the chips.

Scheme 704

Scheme 705

1. Determine the size, the pitch, and the depth of the damaged thread.
2. Adjust the stop collars on the cutting tool as needed. Tap the stop collars to the required depth.
3. Drill out the damaged thread.
4. Remove the chips.
5. Apply clean engine oil to the top thread.
6. Use the tap in order to cut new thread.
7. Clean the thread.
8. Screw the thread insert onto the mandrel of the thread insert installer. Engage the tang of the thread insert onto the end of the mandrel. Important: The thread insert should be flush to 1 turn below the surface.
9. Lubricate the thread insert with clean engine oil - except when installing in aluminum - and install the thread insert.
10. If the tang of the thread insert does not break off when backing out the thread insert installer, break off the tang using a drift punch.

Engine Prelubing

Tools Required

J 45299 Engine Preluber

Important: A constant and continuous flow of clean engine oil is required in order to properly prime the engine. Be sure to use an approved engine oil as specified in the owners manual.

Scheme 706

Scheme 707

1. Remove the engine oil filter and fill with clean engine oil. CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
2. Install the oil filter. Tighten Tighten the oil filter to 30 N.m (22 lb ft).
3. Locate the engine block left oil gallery plug and remove.
4. Install the M16 x 1.5 adapter P/N 509375.
5. Install the flexible hose to the adapter and open the valve.
6. Pump the handle on the J 45299 in order to flow a minimum of 1-1.9 liters (1-2 quarts) engine oil. Observe the flow of engine oil through the flexible hose and into the engine assembly.
7. Close the valve and remove the flexible hose and adapter from the engine.
8. Install the gallery plug to the engine. Tighten Tighten the oil gallery plug to 60 N.m (44 lb ft).
9. Top-off the engine oil to the proper level.

Piston Selection

Important: Measurements of all components should be taken with the components at normal room temperature.

For proper piston fit, the engine block cylinder bores should not have excessive wear or taper.

A used piston and piston pin set may be reinstalled if, after cleaning and inspection, the piston and piston pin are within specifications.

Scheme 708

Scheme 709

Scheme 710

1. Use the J 8087 in order to measure the cylinder bore diameter. Measure at a point 64 mm (2.5 in) from the top of the cylinder bore and 90 degrees to the crankshaft centerline.
2. Measure the J 8087 with a micrometer and record the reading.
3. With a micrometer or caliper at a right angle to the piston pin bore, measure the piston 11 mm (0.433 in) from the bottom of the skirt.
4. Subtract the piston diameter from the cylinder bore diameter in order to determine piston-to-bore clearance. Refer to «Engine Mechanical Specifications»(ref-158806-S02255375142005031600000) .
5. If the proper clearance cannot be obtained, then select another piston and measure the clearances. If the proper fit cannot be obtained, the cylinder bore may require honing or boring.
6. When the piston-to-cylinder bore clearance is within specifications, permanently mark the top of the piston for installation into the proper cylinder.

Scheme 711

Scheme 712

Scheme 713

Scheme 714

Scheme 715

Scheme 716

Scheme 717

1. Apply clean engine oil to the following components: The piston The piston rings The cylinder bore The bearing surfaces
2. Install the J 5239 onto the connecting rod bolts.
3. Install the J 8037 onto the piston and compress the piston rings. Important: The mark on the top of the piston must face the front of the engine block. When assembled, the flanges on the connecting rod and connecting rod cap should face to the front of the engine block on the left bank, and to the rear of the engine block on the right bank.
4. Install the piston and connecting rod assembly, and the J 8037 into the proper cylinder bore.
5. Use the J 8037 and the J 5239 and lightly tap the top of the piston with a wooden hammer handle. Hold the J 8037 firmly against the engine block until all of the piston rings have entered the cylinder bore. Use the J 5239 in order to guide the connecting rod onto the crankshaft journal.
6. Remove the J 5239 . CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
7. Install the connecting rod caps, bearings, and nuts. Tighten Tighten the nuts evenly on the first pass to 27 N.m (20 lb ft). Use the J 36660-A in order to tighten the nuts on the final pass an additional 70 degrees.
8. After the piston and connecting rod assemblies have been installed, lightly tap each connecting rod assembly, parallel to the crankpin, in order to ensure that the connecting rods have side clearance.
9. Use a feeler gage or a dial indicator to measure the connecting rod side clearance between the connecting rod caps. The connecting rod side clearance should be 0.15-0.44 mm (0.006-0.017 in).

Scheme 718

Scheme 719

1. Apply clean engine oil GM P/N 12345610 (Canadian P/N 993193) or equivalent, or engine oil supplement GM P/N 1052367 (Canadian P/N 992367) or equivalent, to the following components: The engine camshaft lobes The camshaft bearing journals The camshaft bearings The distributor drive gear
2. Install three 5/16-18 x 4.0 inch bolts into the engine camshaft front bolt holes. CAUTION: All camshaft journals are the same diameter, so care must be used in removing or installing the camshaft to avoid damage to the camshaft bearings.
3. Use the bolts as a handle in order to install the engine camshaft.
4. Remove the 3 bolts from the front of the engine camshaft.
5. If reusing the fasteners, apply threadlock GM P/N 12345382 (Canadian P/N 10953489) or equivalent, to the threads of the camshaft retainer bolts. CAUTION: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
6. Install the camshaft retainer and bolts. Tighten Tighten the camshaft retainer bolts to 12 N.m (106 lb in).

Balance Shaft

The cast iron balance shaft is mounted in the crankcase above and in-line with the camshaft. A camshaft gear drives the gear attached to the balance shaft. The front end of the balance shaft is supported by a ball-type bearing. The rear end of the balance shaft uses a sleeve-type bearing.

Camshaft

The steel camshaft is supported by four bearings pressed into the engine block. The camshaft timing chain sprocket mounted to the front of the camshaft is driven by the crankshaft sprocket through a camshaft timing chain.

Crankshaft

The cast nodular iron crankshaft is supported by four crankshaft bearings. The number four crankshaft bearing at the rear of the engine is the end thrust bearing. The crankshaft bearings are retained by bearing caps that are machined with the engine block for proper alignment and clearances. The crankshaft position sensor reluctor ring has three lugs used for crankshaft timing and is constructed of powdered metal. The crankshaft position sensor reluctor ring has a slight interference fit onto the crankshaft and an internal keyway for correct positioning.

Cylinder Heads

The cast iron cylinder heads have one intake and one exhaust valve for each cylinder. A spark plug is located between the valves in the side of the cylinder head. The valve guides and seats are integral to the cylinder head. The 4.3L heavy duty applications have pressed in exhaust valve seats. The valve rocker arms are positioned on the valve rocker arm supports and retained by a bolt.

Engine Block

The cast iron engine block has six cylinders arranged in a V shape with three cylinders in each bank. Starting at the front side of the engine block, the cylinders in the left bank are numbered 1-3-5 and cylinders in the right bank are numbered 2-4-6 when viewed from the rear. The firing order of the cylinders is 1-6-5-4-3-2. The cylinders are encircled by coolant jackets.

Exhaust Manifolds

The cast iron exhaust manifolds direct exhaust gases from the combustion chambers to the exhaust system.

Intake Manifold

The intake manifold is a two-piece design. The upper portion is made from a composite material and the lower portion is cast aluminum. The throttle body attaches to the upper manifold. The Central Multipoint Flexible Injection (MFI) system uses multiple fuel injectors to meter and distribute fuel to each engine cylinder. The MFI is retained by a bracket bolted to the lower intake manifold. The fuel meter body also houses the pressure regulator. Metal inlet and outlet fuel lines and nylon delivery tubes connect to the Central MFI unit. The delivery tubes independently distribute fuel to each cylinder through injectors located at the port entrance of each manifold runner where the fuel is atomized.

Valve Train

Motion is transmitted from the camshaft through the hydraulic roller valve lifters and the tubular valve pushrods to the roller type valve rocker arms. The roller type valve rocker arm pivots on a needle type bearing in order to open the valve. The valve rocker arms for each bank of cylinders are mounted to a one piece valve rocker arm support. Each valve rocker arm is retained on the valve rocker arm support and the cylinder head by a bolt. The hydraulic valve lifters keep all the parts of the valve train in constant contact. Each hydraulic valve lifter acts as an automatic adjuster and maintains zero lash in the valve train. This eliminates the need for periodic valve adjustment.

New Product Information

The purpose of New Product Information is to highlight or indicate important product changes from the previous model year.

Changes may include one or more of the following items

1. A component comparison from the previous year
2. Fastener changes
3. Torque values and/or fastener tightening strategies
4. Changed engine specifications
5. New sealants and/or adhesives
6. Disassembly and assembly procedure revisions
7. Engine mechanical diagnostic procedure revisions
8. New special tools required

Component Comparison

1. New Central Multipoint Flexible Injection (MFI) fuel system.
2. EGR valve and components are deleted.
3. Revised lower intake manifold due to the deletion of the EGR.

New Sealants and/or Adhesives

No new sealants or adhesives have been added.

Cleanliness and Care

1. Throughout this section, it should be understood that proper cleaning and protection of machined surfaces and friction areas is part of the repair procedure. This is considered standard shop practice even if not specifically stated.
2. When any internal engine parts are serviced, care and cleanliness is important.
3. When components are removed for service, the components should be marked, organized or retained in a specific order for re-assembly.
4. At the time of installation, the components should be installed in the same location and with the same mating surface as when removed.
5. An automobile engine is a combination of many machined, honed, polished and lapped surfaces with tolerances that are measured in millimeters or thousandths of an inch. The surfaces should be protected to avoid component damage.
6. Apply a liberal amount of clean engine oil to friction areas during assembly.
7. Proper lubrication will protect and lubricate friction areas during initial operation.

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 and organized in a way to ensure reinstallation to original location and position.

Mark or identify the following components

1. Piston and the piston pin
2. Piston to the specific cylinder bore
3. Piston rings to the specific cylinder bore
4. Connecting rod to the crankshaft journal
5. Connecting rod to connecting rod cap
6. Crankshaft bearings and connecting rod bearings
7. Engine camshaft and valve lifters
8. Valve lifters, valve rocker arms, and valve rocker arm supports
9. Valve to the valve guide
10. Valve spring to cylinder head location
11. Engine block bearing cap location and direction
12. Oil pump drive and driven gears

Gasket Reuse and Applying Sealant

1. Do not reuse any gasket unless specified.
2. Gaskets that can be reused will be identified in the service procedure.
3. Do not apply sealant to any gasket or sealing surface unless specified in the service procedure.

Separating Components

1. Use a rubber mallet in order to separate the components.
2. Bump the part sideways in order to loosen the components.
3. Bumping of the component should be done at bends or reinforced areas of the component to prevent distortion of the components.

Cleaning Gasket Surfaces

1. Use care to avoid gouging or scraping the sealing surfaces.
2. Use a plastic or wood scraper in order to remove all the sealant from the components. Do not use any other method or technique to remove the sealant or the gasket material from a part.
3. 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 engine oil. This fine grit is an abrasive and can cause internal engine damage.

Sealant Types

Important: The correct sealant and amount of sealant must be used in the proper location to prevent oil leaks, coolant leaks, or the loosening of the fasteners. DO NOT interchange the sealants. Use only the sealant, or equivalent, as specified in the service procedure.

The following 2 major types of sealant are commonly used in engines

1. Aerobic sealant Room Temperature Vulcanizing (RTV)
2. Anaerobic sealant, which include the following: Gasket eliminator Pipe Threadlock

Aerobic Type Room Temperature Vulcanizing (RTV) Sealant

Aerobic type Room Temperature Vulcanizing (RTV) sealant cures when exposed to air. This type of sealant is used where 2 components, such as the intake manifold and the engine block, are assembled together.

Use the following information when using RTV sealant

1. Do not use RTV sealant in areas where extreme temperatures are expected. These areas include: The exhaust manifold The head gasket Any other surfaces where a different type of sealant is specified in the service procedure
2. Always follow all the safety recommendations and the directions that are on the RTV sealant container.
3. Use a plastic or wood scraper in order to remove all the RTV sealant from the components. CAUTION: Do not allow the RTV sealant to enter any blind threaded hole. RTV sealant that is allowed to enter a blind threaded hole can cause hydraulic lock of the fastener when the fastener is tightened. Hydraulic lock of a fastener can lead to damage to the fastener and/or the components. Hydraulic lock of a fastener can also prevent the proper clamping loads to be obtained when the fastener is tightened. Improper clamping loads can prevent proper sealing of the components allowing leakage to occur. Preventing proper fastener tightening can allow the components to loosen or separate leading to extensive engine damage.
4. The surfaces to be sealed must be clean and dry.
5. Use a RTV sealant bead size as specified in the service procedure.
6. Apply the RTV sealant bead to the inside of any bolt holes areas. Important: Do not wait for the RTV sealant to skin over.
7. Assemble the components while the RTV sealant is still wet to the touch, within 3 minutes. Important: Do not overtighten the fasteners.
8. Tighten the fasteners in sequence, if specified, and to the proper torque specifications.

Anaerobic Type Gasket Eliminator Sealant

Anaerobic type gasket eliminator sealant cures in the absence of air. This type of sealant is used where 2 rigid parts, such as castings, are assembled together. When 2 rigid parts are disassembled and no sealant or gasket is readily noticeable, then the 2 parts were probably assembled using an anaerobic type gasket eliminator sealant.

Use the following information when using gasket eliminator sealant

1. Always follow all the safety recommendations and directions that are on the gasket eliminator sealant container.
2. Apply a continuous bead of gasket eliminator sealant to one flange. The surfaces to be sealed must be clean and dry.

Important

1. Gasket eliminator sealed joint fasteners that are partially torqued and the gasket eliminator sealant allowed to cure more than five minutes, may result in incorrect shimming and sealing of the joint.
2. Do not overtighten the fasteners. Apply the gasket eliminator sealant evenly to get a uniform thickness of the gasket eliminator sealant on the sealing surface. Tighten the fasteners in sequence, if specified, and to the proper torque specifications. After properly tightening the fasteners, remove the excess gasket eliminator sealant from the outside of the joint.

Anaerobic Type Threadlock Sealant

Anaerobic type threadlock sealant cures in the absence of air. This type of sealant is used for threadlocking and sealing of bolts, fittings, nuts, and studs. This type of sealant cures only when confined between 2 close fitting metal surfaces.

Use the following information when using threadlock sealant

1. Always follow all safety recommendations and directions that are on the threadlock sealant container.
2. The threaded surfaces to be sealed must be clean and dry.
3. Apply the threadlock sealant as specified on the threadlock sealant container.

Important

1. Fasteners that are partially torqued and then the threadlock sealant allowed to cure more than five minutes, may result in incorrect clamp load of assembled components.
2. Do not overtighten the fasteners.
3. Tighten the fasteners in sequence, if specified, and to the proper torque specifications.

Anaerobic Type Pipe Sealant

Anaerobic type pipe sealant cures in the absence of air and remains pliable when cured. This type of sealant is used where 2 parts are assembled together and require a leak proof joint.

Use the following information when using pipe sealant

1. Do not use pipe sealant in areas where extreme temperatures are expected. These areas include: The exhaust manifold The head gasket Surfaces where a different sealant is specified
2. Always follow all the safety recommendations and the directions that are on the pipe sealant container.
3. The surfaces to be sealed must be clean and dry.
4. Use a pipe sealant bead of the size or quantity as specified in the service procedure. CAUTION: Do not allow the sealant to enter a blind hole. The sealant may prevent the fastener from achieving proper clamp load, cause component damage when the fastener is tightened, or lead to component failure.
5. Apply the pipe sealant bead to the inside of any bolt hole areas.
6. Apply a continuous bead of pipe sealant to 1 sealing surface. Important: Do not overtighten the fasteners.
7. Tighten the fasteners in sequence, if specified, and to the proper torque specifications.

Tools and Equipment

Special tools are listed and illustrated throughout this section with a complete listing at the end of the section. The tools (or the equivalents) are specially designed to quickly and safely accomplish the operations for which the tools are intended. The use of 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

1. Approved eye protection and safety gloves
2. A clean, well-lit, work area
3. A suitable parts cleaning tank
4. A compressed air supply
5. Trays or storage containers to keep parts and fasteners organized
6. An adequate set of hand tools
7. Approved engine repair stand
8. An approved engine lifting device that will adequately support the weight of the components

Scheme 720

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Scheme 727