2011/05/26 Caterpillar

Landfill Compactor:

836H (S/N: BXD1-UP; XTR1-UP)

Excavator:

385C (S/N: EDA1-UP; KGB1-UP; SBE1-UP; T2E1-UP; KKK1-UP; EAM1-UP; JCM1-UP; WAW1-UP)

390D (S/N: WAG1-UP; BYP1-UP; WAP1-UP; WBT1-UP; KCZ1-UP)

Motor Grader:

24M (S/N: B9K1-UP)

Mobile Hydraulic Power Unit:

385C MHPU (S/N: MSF1-UP)

Off-Highway Truck/Tractor:

772 (S/N: RLB1-UP)

Track-Type Tractor:

D9T (S/N: TWG1-UP; RJS1-UP)

Underground Articulated Truck:

AD45B (S/N: CXM1-UP)

AD55 (S/N: DNW1-UP)

Wheel Dozer:

834H (S/N: BTX1-UP)

Wheel Loader:

988H (S/N: BXY1-UP)

Wheel Tractor-Scraper:

631ESeries II (S/N: 1AB1-1445,1446-UP; 1NB1-UP; 3ND1-UP)

631G (S/N: DFA1-UP; DEM1-UP)

633ESeries II (S/N: 2PS1-UP)

637ESeries II (S/N: 1FB1-531,532-UP)

637E (S/N: 1JB1-UP)

637G (S/N: DFJ1-UP; DEX1-UP)

657E (S/N: 5YR1-UP; 6TR1-UP; 90Z1-UP; 91Z1-UP)

657G (S/N: W1B1-UP; W1C1-UP; W1E1-UP; A4G1-UP)

Service Magazine SEPD1771, 18 April 2014, "New Cylinder Pack Assemblies Are Available in Sets for Certain Machines Equipped with C18 Engines ". Disregard this article. The effectivity has been updated.

ReferenceDisassembly and Assembly, "Pistons and Connecting Rods - Install"

The new 20R-0629 Cylinder Pack As and 20R-0631 Cylinder Pack As are composed of a single piece steel piston with a lower ring land support.

Note: Due to a difference in the weight of the new pistons and existing pistons, the new piston must not be matched with the existing pistons. All the pistons must be replaced in an engine as a set.

The new 20R-0629 Cylinder Pack As is adaptable back to first production on the serial numbers that are listed above. Refer to Table 1 for information on the new cylinder pack assemblies and the parts that are replaced.

Table 1

20R-0629 Cylinder Pack As (18:1 Compression Ratio)
New Part Number Included	Existing Part Number	Part Description
20R-0629	10R-8760	Cylinder pack
368-7818	329-4511	Piston
250-2940	230-2569	Retainer

The new 20R-0631 Cylinder Pack As is adaptable back to first production on the serial numbers that are listed above. Refer to Table 2 for information on the new cylinder pack assemblies and the parts that are replaced.

Table 2

20R-0631 Cylinder Pack As (16.3:1 Compression Ratio)
New Part Number Included	Existing Part Number	Part Description
20R-0631	10R-8763	Cylinder pack
368-7816	329-4510	Piston
250-2940	230-2569	Retainer

Illustration 1	g02552100
Shape of the existing piston that is replaced

Illustration 2	g02552196
Shape of the new piston with the lower ring land support

Refer to Tables 3 and 4 for information on the parts that are included in the new cylinder pack assemblies.

Table 3

Components within the 20R-0629 Cylinder Pack As
Part Number	Description	Quantity
10R-2117	Connecting Rod	1
180-7350	Piston Pin	1
223-9159	Top Piston Ring	1
238-2707	Int. Ring	1
246-5659	Oil Ring	1
250-2940	Pin Retainer	2
368-7818	Piston Body As	1
322-1126	Cylinder Block Liner	1
258-8117	Gasket Kit	1

Table 4

Components within the 20R-0631 Cylinder Pack As
Part Number	Description	Quantity
10R-2117	Connecting Rod	1
180-7350	Piston Pin	1
223-9159	Top Piston Ring	1
238-2707	Int. Ring	1
246-5659	Oil Ring	1
250-2940	Pin Retainer	2
368-7816	Piston Body As	1
322-1126	Cylinder Block Liner	1
258-8117	Gasket Kit	1