797 Cab Glass Can Break in Extreme Cold Weather Caterpillar

797 Cab Glass Can Break in Extreme Cold Weather [TIBU4405]

OPERATOR STATION

CAB GP

797 Cab Glass Can Break in Extreme Cold Weather

CONFIDENTIAL TIBU4405-00

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TECHNICAL INFORMATION BULLETIN	November 24, 2004
Off-Highway Trucks	797 (5YW) 797B (JSM)
	Component Code(s) 7340

SUBJECT: 797 Cab Glass Can Break in Extreme Cold Weather

PROBLEM:

The front windshield glass for the 797 cab (153-3993 Glass) can break during extremely cold weather (-15° C (5° F) to ?40° C (-40° F). It is believed that the 153-3993 Glass breaks due to a combination of the following three factors:

Extremely cold exterior weather (-15° C (5° F) to ?40° C (-40° F)
Defroster heat being blown directly on the 153-3993 Glass by the 151-5715 Louver Assembly
A rapid increase in cab pressure when the operator closes the cab door

SOLUTION:

Construct a diffuser from PVC pipe as a short-term solution while a new diffuser is being developed. Refer to the procedure below.

Procedure to Construct a Diffuser from a PVC Pipe

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Required Parts List
Pt. No.	Description	Qty
9X-2038	Washer	3
8C-6965	Bolt	3
8T-9014	Silicone Sealant	As Required
-	76mm (3") PVC pipe	1.46 meter (57.5") in Length

Cut the PVC pipe in half lengthwise.
In the middle of the top section of the PVC pipe, drill twelve 12mm (.5") holes center spaced at 114mm (4.5") intervals. Ensure that there is distance of 45mm (1.75") between the center of the first hole and the edge of the PVC pipe (see Illustration 1).
Remove the three Torx head bolts on the top of the dash (see Illustration 1).
Install the PVC pipe onto the dash using the 8C-6965 bolts.
Apply a bead of 8T-9014 Silicone Sealant to seal the diffuser to the dashboard.