B5.9G, B5.9LPG – Troubleshooting and Repair Manual – 001-008   Camshaft

The camshaft is gear-driven from the crankshaft. A replaceable bushing is used for the front journal to carry the side-loading from the accessory drive. The remainder of the journals operate in cast-iron bores in the cylinder block; however, these bores can be repaired in a machine shop by installing service bushings.

The camshaft has lobes to operate the intake and exhaust valves. The valve lobes contact “mushroom”-shaped valve tappets that operate the push tubes.

Diagnosing Malfunctions

Loose rocker levers and the need to reset the valve clearance frequently can indicate camshaft lobe or tappet wear. If an inspection of the levers, valve stems, and push tubes does not show wear, then inspect the tappet or camshaft lobe for wear.

An indication of loose tappets is excessive overhead noise.

CAUTION  Anytime a new camshaft is installed, new tappets and push tubes must be installed to reduce the possibility of damage to the camshaft and tappet surfaces.

The camshaft lobes can be inspected after removing the oil pan. Also, the face of the tappets can be inspected after removing the push tubes and lifting the tappets.

A severely damaged camshaft journal(s) can generate small metal particles that can be found in the oil pan and oil filter. These metal particles will also be indicated as iron in the oil analysis. As the clearance in the journal(s)
increases, a small decrease in oil pressure can be detected.

Camshaft Gear Installation/Removal Tool, Part Number 3383589

The camshaft end clearance is determined by the clearance between the camshaft and the thrust plate. The camshaft gear must be removed to adjust the camshaft end clearance.

NOTE: The camshaft does not have to be removed to remove the camshaft gear. Use the camshaft installation and removal tool, Part Number 3823589.

Camshafts that are damaged or worn on the valve lobes must
be replaced. Cummins Inc. does not recommend grinding camshaft lobes.

CAUTION  Anytime a new camshaft is installed, new tappets and push tubes must be installed to prevent damage to the camshaft and tappet surfaces.

• Remove the rocker lever cover. Refer to Procedure 003-011.
• Remove the rocker levers. Refer to Procedure 003-008.
• Remove the push tubes. Refer to Procedure 004-014.
• Remove the drive belt. Refer to Procedure 008-002.
• Remove the vibration damper. Refer to Procedure 001-052 or 001-051.
• Remove the gear cover. Refer to Procedure 001-031.

Tappet Changing Tool, Part Number 3822513

Insert the wooden dowels through the push tube holes and into the top of each tappet securely. When properly installed, the dowels can be used to pull the tappets up and should not be able to be pulled out without considerable effort.

Pull the tappets up and wrap a rubber band around the top of the dowel rods. This will prevent the tappets from dropping down.

Rotate the crankshaft to align the crankshaft with the camshaft timing marks.

Remove the capscrews from the thrust plate.

Remove the camshaft thrust plate.

Remove the camshaft from the cylinder block.

NOTE: Rotate the camshaft as it is being removed. Use extreme care to make sure that the cam bushings are not damaged during the process.

WARNING  When using a steam cleaner, wear safety glasses or a face shield, as well as protective clothing. Hot steam can cause serious personal injury.

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

Use solvent or steam to clean the camshaft.

Dry with compressed air.

CAUTION  Do not touch the machined surfaces with bare hands; this can cause rust to form on the camshaft and edges are very sharp and cause personal injury.

Lubricate the camshaft with clean lubricating engine oil before handling.

NOTE: Anytime a new camshaft is installed, new tappets and push tubes must be installed, also.

Inspect the valve lobes and bushing journals for cracking, pitting, or scoring.

Inspect the camshaft gear teeth for pitting; look for cracks at the root of the teeth.

Measure the valve lobes.

Measure the bearing journals.

Pitting Reuse Criteria

A single pit should not be greater than the area of a 2-mm [0.079-in]-diameter circle.

Interconnection of pits is not allowable and is treated as one pit.

The total pits, when added together, should not exceed a circle of 6 mm [0.236 in].

Only one pit is allowed within ±20 degrees of the nose of the cam lobe.

Edge Deterioration (breakdown) Criteria

The area of edge deterioration should not be greater than the equivalent area of a 2-mm [0.079-in] circle within ±20 degrees of the nose of the cam lobe.

Outside the ±20 degrees of the nose of the cam lobe, the areas of edge deterioration should not be greater than the equivalent area of a 6-mm [0.236-in] circle.

Camshaft Bore – Inspection

Inspect the camshaft bore for obvious damage and excessive wear.

Measure the camshaft bore.

NOTE: If the bores without a bushing are worn beyond the limit, the engine
must be removed for machining and installation of service bushings or replacement of the cylinder block.

Apply a coat of clean lubricating engine oil to the front camshaft bore.

Lubricate the camshaft lobes, journals, and thrust washer with clean lubricating engine oil.

Install the camshaft. While pushing in slightly, rotate the camshaft and carefully work the camshaft through the camshaft bushings. As each camshaft journal passes through a bushing, the camshaft will drop slightly and the camshaft lobes will catch on the bushings. Rotating the camshaft will free the lobe from the bushing and allow the camshaft to be installed.

CAUTION  Do not try to force the camshaft into the camshaft bore or damage to the camshaft bushing can result.

Before the camshaft gear engages the crankshaft gear, check the camshaft for ease of rotation. When installed properly, the camshaft should rotate freely.

Install the thrust washer, align the timing marks as illustrated, and finish installing the camshaft.

Install the thrust washer capscrews.

Verify that the camshaft has proper backlash and end play.

Complete the installation of the removed parts.

• Install the gear cover. Refer to Procedure 001-031.
• Install the vibration damper. Refer to Procedure 001-051.
• Install the drive belt. Refer to Procedure 008-002.
• Install the push tubes. Refer to Procedure 004-014.
• Install the rocker levers. Refer to Procedure 003-008.
• Adjust the valve lash. Refer to Procedure 003-004.
• Install the rocker lever cover. Refer to Procedure 003-011.

• Operate the engine at idle for 5 to 10 minutes, and check for leaks and loose parts.