B5.9G, B5.9LPG – Troubleshooting and Repair Manual – 002-004   Cylinder Head

The cylinder head is a one-piece, cross-flow design with two valves per cylinder. The head has integrally cast valve guides and hardened valve seat surfaces that can be repaired in a machine shop using the appropriate service parts.

The cylinder head has a cast intake manifold, a thermostat housing, and an internal water bypass.

Separate pedestals for each cylinder are to support and route oil to the rocker levers.

The cylinder head gasket is a specialized metal design with a printed o-seal on both sides around the water holes. An embossment in the gasket seals the cylinder bores. As discussed in the Cooling System, the gasket also provides orifices to control coolant flow.

A compression leak to the coolant will normally be detected by loss of coolant as the coolant is blown from the cooling system.

The sound emitted from the overhead can indicate a valve train problem. Loose rocker levers will clatter. A squeaking noise can mean lack of lubrication for the adjusting screw and the push rod socket.

Valve leakage is often audible from the intake and exhaust manifolds.

If the compression is low on one or more nonadjacent cylinders and the pressure can not be increased by oiling the rings, improper valve sealing is to be suspected.

WARNING  Fuel is flammable. Keep all cigarettes, flames, pilot lights, arcing equipment, and switches out of the work area and areas sharing ventilation to reduce the possibility of severe personal injury or death when working on the fuel system.

WARNING  Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.

WARNING  Coolant is toxic. Keep away from children and pets. If not reused, dispose of in accordance with local environmental regulations.

WARNING  Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50°C [120°F] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.

• Turn off the vehicle’s main fuel shutoff valve.
• Disconnect the battery cables, negative (-) cable first.
• Drain the coolant. Refer to Procedure 008-018.
• Remove all water and heater hoses.

Remove the turbocharger and exhaust manifold. Refer to Procedures 010-033 and 011-007.

Remove the spark plugs and plug wires. Refer to Procedure 013-014.

Remove the ignition coils.

Remove the rocker lever cover, rocker levers, and push rods. Refer to Procedures 003-011, 003-008, and 004-014.

Remove the intake manifold cover. Refer to Procedure 010-023.

NOTE: Note the manifold cover orientation for proper direction during installation.

Remove the drive belt. Refer to Procedure 008-002.

NOTE: Removal is easier if the crankshaft pulley is loosened before removing the belt.

Remove the belt tensioner and bracket. Refer to Procedure 008-087.

Remove the fan hub assembly. Refer to Procedure 008-036.

NOTE: Omit this step if the fan bracket is not attached to the cylinder head.

Loosen the alternator link, mounting bolt, and water inlet connection capscrews.

Remove the alternator bracket mounting capscrews, and pivot the alternator away from the engine. Refer to Procedure 013-001.

Remove the thermostat housing assembly and bracket from the engine. Refer to Procedure 008-013.

Remove the cylinder head capscrews in the sequence shown.

WARNING  This component weighs 23 kg [50 lb] or more. To reduce the possibility of personal injury, use a hoist or get assistance to lift this component.

CAUTION  Do not lay the cylinder head on the combustion deck. This can damage the cylinder head deck.

Remove the cylinder head and gasket from the cylinder block. Be sure that the head is removed in a direct upward direction.

Scrape the gasket material from all gasket surfaces on the block and head.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

Clean the buildup of deposits from the coolant passages. Excessive deposits can be cleaned in an acid tank, but the expansion plugs must first be removed.

WARNING  Do not mix gasoline, alcohol, or gasohol with diesel fuel. This mixture can cause an explosion.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

WARNING  Use skin and eye protection when handling caustic solutions to reduce the possibility of personal injury.

Clean the cylinder head combustion deck with a Scotch-Brite™ pad, or an equivalent cleaning pad, and diesel fuel or solvent.

WARNING  Wear protective eye covering while cleaning carbon deposits to reduce the possibility of eye injury.

Clean carbon deposits from the valve pockets with a high-quality steel wire wheel installed in a drill or a die grinder.

NOTE: An inferior-quality wire wheel will lose steel bristles during operation, thus causing additional contamination.

WARNING  Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.

Wash the cylinder head in hot, soapy water solution.

After rinsing, use compressed air to dry the cylinder head.

WARNING  Use skin and eye protection when handling caustic solutions to reduce the possibility of personal injury.

CAUTION  Do not use caustic or acidic solutions to clean the cylinder head capscrews. Use of these solutions can cause corrosion.

Use a petroleum-based solvent to clean the capscrews.

Clean the capscrew thoroughly with a wire brush or a soft wire wheel, or use a nonabrasive bead blast to remove deposits from the shank and the threads.

Use a straightedge and feeler gauge to measure the overall flatness of the cylinder block. The overall flatness, end-to-end and side-to-side, must not exceed 0.075 mm [0.003 in].

Inspect the combustion deck for any localized dips or imperfections. If present, the cylinder block head deck must be ground.

Refer to the Alternate Repair Manual, Bulletin 3666109, for grinding/milling procedures and limitations.

These guidelines apply only to cracks extending from the spark plug bore to the intake valve seats. Replace cylinder heads that exhibit valve bridge cracks in any other location.

The reuse guidelines for a cylinder head with a crack extending from the spark plug bore to the intake valve seat are as follow:

If the crack does not extend into the valve seat, the cylinder head is reusable.

If the crack extends into or through the valve seat, the cylinder head must be repaired by installing a valve seat insert according to the Alternative Repair Manual, Bulletin 3666109.

Use a straightedge and a feeler gauge to measure the cylinder head combustion surface for flatness.

Inspect the cylinder head capscrews for damaged threads, corroded surfaces, or a reduced diameter (due to capscrew stretching).

Do not reuse cylinder head capscrews under the following conditions:

• Visible corrosion or pitting exceeds 1 cm² [0.155 in²] in area.
• Acceptable is 3/8 x 3/8 inch.
• Unacceptable is 1/2 x 1/2 inch.
• Visible corrosion or pitting exceeds 0.12 mm [0.005 in] in depth.

• Visible corrosion or pitting is located within 3.2 mm [1/8 in] of the fillet.
• Visible corrosion or pitting is located within 3.2 mm [1/8 in] of the threads.
• Stretched beyond “free-length” maximum. Refer to the measurement procedure below:

NOTE: If the capscrews are not damaged, they can be reused throughout the life of the engine unless the specified “free length” is exceeded.

Use capscrew length gauge, Part Number 3823921, or equivalent, to check the capscrew free length. Place the head of the capscrew in the appropriate slot with the flange against the base of the slot.

If the end of the capscrew touches the foot of the gauge, the capscrew is too long and must be discarded.

CAUTION  Be sure the gasket is correctly aligned with holes in the cylinder block. If the gasket is not aligned correctly, engine damage can result.

Position a new cylinder head gasket over the dowels.

“TOP” and the part number must be facing up on the gasket.

WARNING  The component weighs 23 kg [51 lb] or more. To reduce the possibility of personal injury, use a hoist or get assistance to lift the component.

Carefully put the cylinder head straight down onto the cylinder block, and seat it onto the dowels.

Position the push tubes into the valve tappets.

Lubricate the push tube sockets with clean lubricating engine oil.

Lubricate the valve stems with clean gas engine lubricating oil.

Completely loosen the rocker lever adjusting screws.

NOTE: The rocker lever pedestals are aligned with dowels.

Install the pedestals.

Lubricate the 8-mm pedestal capscrew threads and under the capscrew heads with clean lubricating engine oil.

Install the capscrews finger-tight.

Lubricate the 12-mm pedestal/head capscrew bolt threads and under the capscrew heads with clean lubricating engine oil.

Install the capscrews finger-tight.

Lubricate the threads and under the heads on the remaining cylinder head capscrews with clean gas engine lubricating oil.

Install capscrews in the cylinder head and finger-tighten.

Step 1:

1. Follow the numbered sequence, and tighten all 26 capscrews.

Step 2:

2. Follow the numbered sequence, and tighten the six long capscrews only (numbers 4, 5, 12, 13, 20, and 21).

Step 3:

3. Retighten the short capscrews (numbers 1, 2, 3, 6, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 22, 23, 24, 25, and 26) because of cylinder head relaxation and to obtain proper cylinder head torque requirements.

Step 4:

4. Repeat step 2 because of cylinder head relaxation and to obtain proper cylinder head torque requirements.

Step 5:

Follow the numbered sequence, and turn the capscrew 90 degrees as indicated on the capscrew head.

To turn the capscrew to the desired angle accurately, align the capscrew with the small “dot” and “window” that are marked on the capscrew head or use recommended torque angle gauge, Part Number 3823878, or equivalent, torque angle gauge for 19 mm [3/4-in] drive.

Mark the cylinder head adjacent to the dot on the capscrew head. This mark will serve as an indexing aid.

Rotate the capscrew until the mark that has been made on the cylinder head falls into the window on the capscrew head.

Use a permanent marker to mark the socket corresponding to one of the flats of the socket hex.

After the torque has been applied, mark the cylinder head at the location of the dot.

Position the socket on the capscrew such that the mark on the socket is at the same point as the window on the capscrew.

Turn the socket until the mark on the socket aligns with the mark on the cylinder head.

Tighten the 8-mm pedestal capscrews.

Adjust the valve clearance. Refer to Procedure 003-004.

Install the rocker lever covers, and tighten capscrews.

Install the manifold cover plate.

Install the spark plugs, coils, and plug wires. Refer to Procedure 013-016.

Install the exhaust manifold and turbocharger. Refer to Procedures 011-007 and 010-033.

Install the thermostat and thermostat housing. Refer to Procedures 008-013.

Install the fan hub. Refer to Procedure 008-036.

Install the fan hub pulley. Refer to Procedure 008-039.

Install the tensioner bracket to the cylinder head.

Tighten the socket head screws.

Position the belt tensioner on the bracket, and secure it with the capscrew.

NOTE: Some tensioners can be bolted to two different locations on the bracket. Install in the location dictated by your requirement.

Install alternator and alternator bracket. Refer to Procedures 013-001.

Assemble the alternator bracket to the thermostat housing. Refer to Procedure 013-001.

Check the alternator pulley alignment. Use a straightedge to make sure it is aligned with the other pulleys and is parallel to the front face of the block.

Tighten all capscrews in the following sequence:

1. Alternator-to-alternator bracket capscrew
2. Lower brace-to-alternator capscrew
3. Alternator-to-water inlet capscrew
4. Water inlet-to-block capscrews.

Wrench size and torque value is determined by the make and model of alternator. Refer to Procedure 018-009 in Section V.

Lift the tensioner, and install the belt.

Service Tip: If difficulty is experienced installing the drive belt (the belt seems too short), position the belt over the grooved pulleys first; and then, while holding the tensioner up, slide the belt over the water pump pulley.

WARNING  Coolant is toxic. Keep away from children and pets. If not reused, dispose of in accordance with local environmental regulations.

WARNING  Do not remove the pressure cap from a hot engine. Wait until the coolant temperature is below 50° [120°] before removing the pressure cap. Heated coolant spray or steam can cause personal injury.

WARNING  Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.

WARNING  Fuel is flammable. Keep all cigarettes, flames, pilot lights, arcing equipment, and switches out of the work area and areas sharing ventilation to reduce the possibility of severe personal injury or death when working on the fuel system.

• Install all water and heater hoses.
• Add the coolant. Refer to Procedure 008-018.
• Connect the battery cables, positive (+) cable first.
• Turn on the vehicle’s main fuel shutoff valve.