1977/05/02 Caterpillar

6.25"
Bore, Six Cylinder Engines in All Applications

SUPPLEMENT: 11/13/78

SERVICE MAGAZINE, MAY 2, 1977, PAGE 2. In the article "Improved Cylinder Block With Spacer Plate Used With New Cylinder Heads, Cylinder Head Gaskets, Cylinder Liners And Timing Gear Housing," put a mark through the information in the CAUTION at the bottom of the right column on page 2. In the place of the information that was in the "CAUTION", use the following information:

... When replacement of the head gaskets is necessary on engines equipped with the former 1S2587 Cylinder Liners--Grooved, use 8M2970 Cylinder Head Gaskets--Metal Asbestos and 4S9155 Gaskets--Minor Side.

... When replacement of the cylinder liners is necessary on engines that have the former counterbored cylinder block, use 7N5681 Cylinder Liners--Non-Grooved and 7N3083 Cylinder Head Gaskets--Wire Ring.

... Do not mix the grooved and non-grooved cylinder liners under a cylinder head. Use either all grooved or non-grooved cylinder liners under a cylinder head with the correct gaskets.

... Do not use wire ring cylinder head gaskets with the former grooved cylinder liners.

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Description of Change: An improved cylinder block is used in the 6.25" bore, six cylinder engines. The new cylinder block has spacer plates to go between the cylinder block and the cylinder heads. The former cylinder block had counterbores machined in its top surface for the cylinder liners. The new cylinder block design will prevent cracks in the counterbores under the cylinder liner flanges that were seen on some of the former cylinder blocks. In addition to the new cylinder block, new improved cylinder heads, new improved cylinder head gaskets, new cylinder liners, and a new timing gear housing are used. A list of the changes and improvements follows:

1) The new timing gear housing has two sets of bolt holes that are used to hold the timing gear housing to the top of the cylinder block. The upper set of holes has plugs. The plugs are to be removed only if the housing is used on an engine that has the former cylinder block.

2) The oil drain line from the turbocharger to the cylinder block for D9 Tractors and 594 Pipelayers is changed because the hole for the oil drain line is in a new location on the new cylinder block.

3) Bolts are used to hold the new cylinder head. Formerly, studs in the cylinder block were used to hold the cylinder head. This change will make removal of the gasket for the spacer plate easier and make it easier to clean the top of the cylinder block during a repair.

4) New lifting eyes are used with the cylinder head bolts. A plate is added to the front lifting eye for industrial and marine engines for additional strength.

5) Additional cylinder head bolts are added on the push-rod side of the cylinder head. The additional bolts will give more even force on the gaskets to prevent oil leaks.

6) New seals are used for the coolant passages between the cylinder head and the cylinder block. The new cylinder head does not have counterbores in the bottom for seals like the former heads. The new seals give a positive seal at both the ends of the coolant passages.

7) The improved head gasket is one piece. This gasket has a wire ring at the openings of the cylinders for an improved seal. New cylinder liners are used with the new head gasket. The new cylinder liners have a smaller chamfer on the top outer corner of the flange and no groove in the top face of the flange.

8) An improved cylinder head assembly is used for parts service on engines that have the former cylinder block. The new cylinder head assembly has a stronger casting.

Adaptable To: The new cylinder block is adaptable to all 6.25" bore, six cylinder engines. Extra parts are needed for engines that had the former cylinder block. See Chart 2.

Chart 2 shows the parts needed to install the new cylinder block in an engine that had the former cylinder block. Since the former cylinder block is canceled, the new parts will be sent if the former cylinder block is ordered. Always give the engine serial number and engine arrangement number when you order parts from Chart 2. If the engine does not have a serial number, give the machine model number and machine serial number. See the notes about the cylinder liners and the timing gear housing after Chart 2.

NOTE: When the new cylinder block is installed in an engine that had the former cylinder block, it is not necessary to use the new 7N5681 Cylinder Liners if the former liners can be used again and are inspected as follows to see that there is an acceptable seal between the cylinder liners and the cylinder head gasket.

1) Look at the top and side surfaces of the liner flanges. If there are any dents (damage caused by impact) or nicks (small pieces of material removed) in the top or side surfaces of the liner flange, the cylinder liner can not be used with the new cylinder block.

2) Install the cylinder liners in the cylinder block. Put the cylinder head gasket on the top of the cylinder block. If any of the openings for the cylinders in the cylinder head gasket are not centered (equal gap between the gasket and liner all around the circumference) on the top surface of the cylinder liner, that cylinder liner can not be used with the new cylinder block.

NOTE: When the new cylinder block is installed in an engine that had the former cylinder block, it is not necessary to use the new timing gear housing. It is necessary to make modifications to the former timing gear housing to use it with the new cylinder block. The instructions to make the modifications follow:

Procedure To Make Modifications To Timing Gear Housing

The top two holes in the former timing gear housings that were used to hold the timing gear housing to the cylinder block are higher than the top of the new cylinder block. These two holes must be plugged (filled so they will not leak) and two new holes must be machined in lower positions. The procedure that follows gives instructions to do this.

1) Mark points A and B on the timing gear housing as shown in Illustration 1.

Illustration 1--Locations of points A and B.

2) Machine 1.500" (38.10) diameter holes at points A and B.

3) Make 1 1/4" NPT threads in the two holes so that the end of a 1 1/4" solid pipe plug can be installed even with the face of the timing gear housing toward the cylinder block.

NOTE: On most housings there may be part of casting openings that are not machined out as shown in Illustration 2. These small casting openings on the lower part of the holes are acceptable.

Illustration 2--Casting openings as shown is acceptable.

4) Clean the two holes and two 1 1/4" solid cast iron pipe plugs with 8M8060 Primer. Put 5P3413 Thread Sealant on the threads and install the two pipe plugs.

5) Machine the ends of the plugs so they are even with the surface of the timing gear housing toward the cylinder block.

6) Drill holes C and D to .547" (13.89 mm) diameter as shown in Illustration 3.

Illustration 3--Locations of holes C and D.

7) Use a 1.125" (28.58 mm) drill bit that has a flat end to remove any material on the ends of the two .547" (13.89 mm) diameter holes that are not even with the surface of the timing gear housing toward the flywheel housing.

8) This step is optional. Drill and make threads in holes for 10-32 screws opposite the .547" (13.89 mm) diameter holes on the pitch line of the pipe plugs. Do not drill deeper than .31" (7.87 mm). Install two 10-32 screws. Machine the ends of the screws so they are even with the surface of the timing gear housing toward the cylinder block.