1-1/4 inch
Remove the following parts:
• Unloader cover (1)
• Copper washer (2)
• Unloader pin (4)
• Spring (5)
Discard the copper washer.
Remove and discard the o-ring (3).
9/16 inch
Remove the four cylinder head capscrews (6).
Remove the cylinder head (7).
Remove and discard the cylinder head gasket (8).
Service Tip: Scribe a mark to show proper head orientation before removing the head.
Part No. 3823528, Air Com pressor Seat Socket or 3/4 inch Allen Wrench.
Install the head with the bottom side up in a soft jawedvise.
Remove the exhaust valve seat (9).
Remove the following parts:
• Exhaust valve disc (10)
• Spring (11)
• Copper washer (2)
Discard the copper washer.
NOTE: The exhaust valve stop is pressed in place and must not be removed.
Part No. 3823528, Air Compressor Seat Socket
Remove the inlet valve cage (12).
Remove the following parts:
• Spring (11)
• Inlet valve disc (10)
• Inlet valve seat (13)
• Copper washer (2)
Discard the copper washer
Cleaning
Warning: When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing.
Soak the parts in a kerosene emulsion based cleaner designed to remove carbon. The cleaner must have a pH
of 9.5 or less to avoid turning aluminum parts black. The cleaner manufacturer or supplier can be contacted about
solution concentration, temperature and soak time.
Caution: Do not use a scraper to remove carbon and scale. This can damage sealing surfaces.
Use a stiff non-metalic bristle brush to scrub the parts.
Cleaning
Valve Discs
Inspect and replace if cracked, pitted or grooved in excess of 0.13 mm [0.005 in].
Inlet Valve Seat
Measure the distance from the valve seating surface to the surface that contacts the valve cage.
Replace the intake valve seat if not within limits or if cracked or damaged.
Exhaust Valve Seat
Inspect the seat for damage and wear.
Measure the valve guide diameter.
Replace the exhaust valve seat if not within limits.
Measure the distance from the top of the valve seat to the valve seating surface.
Replace the exhaust valve seat if not within limits.
Inlet Valve Cage
lnsPect the inlet valve cage for damage and wear.
Measure the valve guide diameter.
Replace the inlet valve cage if not within limits.
Measure top of cage to valve stop.
Exhaust Valve Stop
Inspect the exhaust valve stop. Replace the cylinder head assembly if the stop is loose or damaged.
Measure the distance from the valve end of the stop to the face of the cylinder head.
Replace the cylinder head if not within limits.
Unloader Pin
Inspect for scoring or pitting.
Measure the length of the pin.
Replace the pin if not within limits.
Valve Springs
Use valve spring tester, part No. 3375182, to check the springs.
Replace if not within limits in Table 1, shown below.
NOTE: Cummins Engine Company, Inc. recommends that new springs be installed during rebuild.
Cylinder Head
Inspect and replace if cracks, nicks, gouges or damaged threads are found.
Inspect the unloader seal bore for scoring or pitting.
Replace the cylinder head if damaged.
Assembly
Turn the cylinder head bottom side up and install it in a soft jawed vise.
Install the following parts.
a. New washer
b. Inlet valve seat
c. Inlet valve
d. Inlet valve spring
Air Compressor Seat Socket, Part No. 3823528 and
Torque Wrench
Tighten the cage.
Torque Value: 108 N*m [80 ft-lb]
Install the following parts:
a. New washer
b. Exhaust valve spring
c. Exhaust valve disc
3/4 inch Allen Wrench or Air Compressor Seat Socket, Part No 3823528, and Torque Wrench
Tighten the seat.
Torque Value: 108 N»m [80 ft-lb]
Install a new gasket and the cylinder head to the cylinder block, aligning the scribe marks.
Install the four capscrews.
9/16 inch and Torque Wrench
Tighten the capscrews.
Torque Value: 30 N®m [22 ft-lb]
Tighten the capscrews again, in the sequence shown.
Torque Value: 41 N®m [30 ft-lb]
Install a new o-ring on the unloader pin.
1-1/4 inch and Torque Wrench
Install the following parts:
a. Spring
b. Unloader pin
c. New washer
d. Unloader cover
Tighten the cover.
Torque Value: 41 N«m [30 ft-lb]
Warning: The air discharge line must be capable of with standing extreme heat and pressure to prevent personal
injury and property damage. Refer to the manufacturer’s specifications.
Continue to check for carbon buildup in the air discharge line connections up to the first or wet tank.
Clean or replace any lines and fittings with carbon deposits greater than 1.6 mm [0.06 (1/6 inch]. Refer to the
manufacturer’s specifications for cleaning or replacement instructions.
Install and tighten the air inlet and outlet connections.
NOTE: Torque of discharge line dependent upon line size and type. Consult vehicle manufacturer for correct torque
value.
Close the wet tank draincock.
Operate the engine and check for air leaks.
