VALVE GP-RELIEF 4523625 - Caterpillar

Illustration 10
6V-7840 Deck Checking Tool Assembly. The assembly includes 4B-9820 Wrench, 7B-7640 Wrench, and 6B-7225 Wrenches (11).
Measuring Height of Block Deck
Illustration 11
Measurement of block top deck.
(C) Height of block.
(12) Identification of resurfaced block.
(13) Crankshaft bore.
Should the block require resurfacing, the specifications in Chart E should be used. These are independent of the amount of material removed from the cylinder head, which has separate specifications. Manufacturing attempts to machine blocks to dimension greater than 321.75 mm (12.667 in). However, if the block is machined between 321.75 mm (12.667 in) and 321.50 (12.657 in) a "TG" (thick gasket) identifier must be stamped as shown in Illustrations 11 and 12.
Illustration 12
Top view of "TG" marking location (12) for resurfaced blocks.
Chart E. Dimensions for Height of Block Top Deck
Description Dimension
Surface flatness 0.05 (.002) for any
150 (6.0) span
New block height5 322.00 _b1_
0.017
(12.677 _b1_
.0007)
Minimum block height5
(standard head gasket) 321.75 (12.667)
Absolute minimum height5
(special head gasket) 321.50 (12.657) Note: All dimensions are mm (in).
5 Measured from centerline of main bearing bore.
3126 Engine blocks with heights less than 321.75 mm (12.667 in) require the use of a special 119-2948 Cylinder Head Gasket. This gasket is 0.25 mm (.010 in) thicker than the standard head gasket.
The thicker head gaskets allow the block deck to be resurfaced below what would be possible with the standard head gasket. The increased material removed from the block deck causes the pistons to project higher above the block surface at top dead center (TDC). The thicker head gasket keeps the pistons from hitting the cylinder head and valves.
If the block is re-surfaced, it should be identified on the left hand side in the middle of the block on a pad at the block-to-head joint (12, Illustrations 11 and 12). It is recommended the same location and identifier "TG" (thick gasket) used with remanufactured blocks should also be used on dealer resurfaced blocks.
Note: The thicker cylinder head gaskets should not be used unless the block has been resurfaced below the minimum specified measurement. Using this thicker gasket when it is not needed will result in a lower compression ratio and may cause hard starting, excessive white smoke, etc.
Repairing Block Top Deck with Metal Spray
A metal spray process can also be used to restore the contact surfaces to their original dimensions. An acceptable process is the METCO 6P II Thermospray System. Refer to SERF8704, "Flame Spray Guide", for information about metal spray repair procedures. For complete information, contact Repair Process Engineering of the Marketing & Product Support Division at 1 (309) 675-5434, for use or applications of the metal spray process.
SEBF8277 CATERPILLARAE A92006 Caterpillar