2003/12/01 Caterpillar

Caterpillar Products:

3500 Family Generator Sets and Power Modules

3500 Family Pumpers

Engine: Commercial

3500 and 3500B Family All

Engine News SEBD9328, December 2003, "New Cylinder Head Groups and Valve Mechanisms". Disregard this article. Corrections have been made to the supplement. The correct information follows.

Description of Change: New cylinder head groups and assemblies are available for all 3500 and 3500B Engines. The new head groups and assemblies include a new exhaust valve with a larger stem diameter and an exhaust valve guide with a larger inside diameter. The larger stem diameter reduces stress in the valve stem during severe engine operation. The new groups also include floating valve bridges that eliminate the need for bridge adjustments. The new groups also include the following new components: valve springs, rotators, spring washers and valve stem seals.

Adaptable To: Use the new basic cylinder head groups for Top End overhauls and for Major overhauls on all 3500 and 3500B Engines. The new basic cylinder head groups may be used individually in replacement of the former basic cylinder head groups.

The former cylinder head groups and the new cylinder head groups are listed in Table 1.

Table 1

Cylinder Head Group	Former Basic Cylinder Head Group	New Basic Cylinder Head Group
3500 Engine with EUI
7E-8758 Cylinder Head Gp	172-0837 Cylinder Head Gp	239-0691 Cylinder Head Gp
3500 MUI Engine (Locomotive)
203-2170 Cylinder Head Gp	203-2144 Cylinder Head Gp	239-0692 Cylinder Head Gp
3500 MUI Engine
4W-0095 Cylinder Head Gp	172-0835 Cylinder Head Gp	239-0690 Cylinder Head Gp
3500B Engine
101-0830 Cylinder Head Gp	145-3216 Cylinder Head Gp	201-4257 Cylinder Head Gp
3500B Engine (Locomotive)
203-2169 Cylinder Head Gp	203-2168 Cylinder Head Gp	234-8779 Cylinder Head Gp

Use the new individual parts for replacement of any former individual parts. If any of the new parts are installed, all of the former parts on that side of the cylinder head must be replaced with the new parts. For example, if one inlet valve spring is replaced with the corresponding new spring, then all of the springs on both inlet valves, both of the seals, and both of the valve rotators must be replaced with the new part numbers. The former parts and the new parts of the basic cylinder head groups are listed in Table 2.

Table 2

Former Part Number	New Part Number
133-9306 Valve Guide (Inlet and Exhaust)	133-9306 Valve Guide (Inlet)
	197-6995 Valve Guide (Exhaust)
210-2542 Inlet Valve	210-2542 Inlet Valve
210-2529 Exhaust Valve	194-4897 Exhaust Valve
137-6856 Seal	197-7006 Seal
2W-2662 Spring Seat	209-0962 Washer
101-1180 Outer Spring	194-4901 Outer Spring
7N-1904 Outer Spring
101-1177 Inner Spring	194-4902 Inner Spring
7N-1903 Inner Spring
197-6999 Rotocoil Assembly (Inlet and Exhaust)	197-7062 Rotocoil Assembly (Inlet)
	197-7063 Rotocoil Assembly (Exhaust)
2A-4429 Retainer Lock (Inlet and Exhaust)	2A-4429 Retainer Lock (Inlet)
	197-7055 Retainer Lock (Exhaust)
8T-6759 Pipe Plug	8T-6759 Pipe Plug
7N-1902 Dowel	239-0689 Dowel (1)
133-9307 Rotocoil Assembly	234-8777 Rotocoil Assembly is serviced by the 197-7063 Rotocoil Assembly and the 234-8776 Shield . (2)
129-4181 Bridge Assembly	230-3152 Bridge (Exhaust)
	230-3153 Bridge (Inlet)

( 1 )	Only required on 3500 MUI
( 2 )	Only required on 3500 Locomotive

The bridge dowels must be removed and/or a bridge dowel must be modified when a cylinder head that originally had adjustable bridges is rebuilt.

Because of the design of the floating bridge, the cylinder head for a 3500 Engine with EUI and for a 3500B Engine does not require any dowels.

Because force is placed on the fuel injector by the rack, the cylinder head for a 3500 MUI Engine requires one 239-0689 Dowel in order to maintain correct orientation of the fuel injector.

Illustration 1	g01023120
(1) 239-0689 Dowel in a cylinder head for a 3500 MUI Engine

When the cylinder head for a 3500 MUI Engine is rebuilt, only the right hand dowel is installed. The dimension from the surface of the cylinder head to the top of the dowel must not exceed 30 mm (1.2 inch). Use a 239-0689 Dowel for the correct orientation of the 3500 MUI fuel injector.

Illustration 2	g01097665
Typical example of the slotted pocket in the floating valve bridge

When viewing the bottom of the new valve bridges the new valve bridges have a pocket on either end for each tip of the valve stem. One of the pockets is round and the other pocket is slotted. The bridge must be placed on the cylinder head so that the round pocket is toward the outside of the engine. Refer to Illustration 3. This orientation of the valve bridge is more stable. This orientation keeps the bridge in position during the initial valve lash adjustment after an engine rebuild.

Illustration 3	g01097686
Orientation of the valve bridge (1) Round pocket (2) Outside of the engine

Table 3 lists the effectivity for the new cylinder head groups and assemblies.

Table 3

Effectivity of the New Cylinder Head Groups in 3500 Engines
3500 Engine with EUI
Serial Number	Serial Number
S/N:3LS00228-UP	S/N:3ZW00473-UP
S/N:3MS00233-UP	S/N:5PS00315-UP
S/N:3NS00246-UP	S/N:7KM00077-UP
3500 MUI Engine (Locomotive)
S/N:2WK00087-UP
3500 MUI Engine
S/N:1JZ00603-UP	S/N:67Z02050-UP
S/N:1KZ01244-UP	S/N:68Z01252-UP
S/N:1LZ00524-UP	S/N:69Z00889-UP
S/N:23Z07938-UP	S/N:70Z01077-UP
S/N:24Z10152-UP	S/N:71Z00403-UP
S/N:25Z07100-UP	S/N:72Z00567-UP
S/N:27Z00851-UP	S/N:73Z00968-UP
S/N:29Z01389-UP	S/N:95Y01216-UP
S/N:49Y01032-UP	S/N:96Y02060-UP
S/N:50Y01802-UP	S/N:CTD00183-UP
S/N:65Z01130-UP	S/N:CTE00333-UP
S/N:66Z00939-UP	S/N:CTF00263-UP
S/N:2TS00008-UP	S/N:3HM00015-UP
S/N:3JS00009-UP	S/N:51Y00861-UP
S/N:8TL00011-UP	S/N:97Y00742-UP
S/N:9WN00358-UP	S/N:LPD00005-UP
3500B Engine
S/N:1FZ01864-UP	S/N:7SM00910-UP
S/N:1GZ01498-UP	S/N:8CN00212-UP
S/N:1NW00145-UP	S/N:8EM00508-UP
S/N:1PW00427-UP	S/N:8KN00567-UP
S/N:1TW00347-UP	S/N:8RM00754-UP
S/N:2AF00364-UP	S/N:9AN00358-UP
S/N:2BM00186-UP	S/N:AAG00006-UP
S/N:2EZ00331-UP	S/N:BAG00025-UP
S/N:2FW00334-UP	S/N:BPX00098-UP
S/N:2GW00401-UP	S/N:BRC00154-UP
S/N:2HW00248-UP	S/N:BRN00192-UP
S/N:2JW00409-UP	S/N:CAN00111-UP
S/N:3CW00254-UP	S/N:CBB00189-UP
S/N:3DM00451-UP	S/N:CBN00312-UP
S/N:3DW00175-UP	S/N:CDE00313-UP
S/N:3KD00266-UP	S/N:CTA00153-UP
S/N:4AW00816-UP	S/N:CTB00186-UP
S/N:4BW00544-UP	S/N:CTC00254-UP
S/N:4DR00007-UP	S/N:CTD00183-UP
S/N:4GM00743-UP	S/N:CTE00333-UP
S/N:4TN00786-UP	S/N:CTF00263-UP
S/N:5AW00135-UP	S/N:CTG00267-UP
S/N:6WN00803-UP	S/N:CTH00235-UP
S/N:7HM00264-UP	S/N:CTJ00200-UP
S/N:7RN01949-UP	S/N:FFG00018-UP
S/N:S2X00102-UP	S/N:S2E00102-UP
S/N:1HZ02430 and 02443-UP
3500B Engine (Locomotive)
S/N:8DF00187-UP	S/N:BCK00274-UP
S/N:9WF00118-UP	S/N:PWG00110-UP