RING-PISTON 5B0904 - Caterpillar

Introduction
The problem that is identified below has a known permanent solution. Use the solution that is identified below.Problem
Insufficient fusion has been observed in the firewall bracket weld on certain 307E Mini Hydraulic Excavators. This insufficient fusion can lead to a crack in the weld.Solution
Rework the weld on the bracket after the weld has failed or cracked. Follow the rework procedure as shown.Rework Procedure
Accidental engine starting can cause injury or death to personnel working on the equipment.To avoid accidental engine starting, disconnect the battery cable from the negative (−) battery terminal. Completely tape all metal surfaces of the disconnected battery cable end in order to prevent contact with other metal surfaces which could activate the engine electrical system.Place a Do Not Operate tag at the Start/Stop switch location to inform personnel that the equipment is being worked on.
Personal injury can result from flame cutting or welding on painted areas.The effect of gasses from burned paint is a hazard to the person doing the cutting or welding.Do not flame cut or weld on painted areas.
Before carrying out arc welding on the machine or on any equipment attached to the machine, disconnect all power and ground leads from the batteries in order to avoid possible damage to electronic components.
Park the machine on level ground with the implements lowered.
Turn off the engine. Turn off the battery isolator switch.
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Unbolt two firewall bracket bolts and the engine left door (cab side) hinge bolts.
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Remove the door and keep the door.
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Grind off the cracked weld and ensure that the area is free from oil, grease, paint, and dirt before rewelding.
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Protect the surrounding area using a fire proof blanket with only the welding area exposed.Note: Use a 3.2 mm (0.13 inch) E4303 electrode or equivalent to maintain a 188 A electrical power for the weld repair work.
Perform a fillet weld for the full length of 87 mm (3.43 inch) with a minimum 3 mm (0.12 inch) weld leg size.
Remove the weld slag and touch up the weld with a light grinding or a sanding after the welding.
Use a dye penetrant or the magnetic particle inspection for the weld. Repeat the steps above if the weld is unsatisfactory.
Illustration 5 g03577462
Illustration 6 g03577463
Touch up the weld and the affected area with primer and paint after the weld has cooled.Note: The weld must be free from cracks, porosity, undercut, and incomplete fusion.
Reassemble the left engine door and the two firewall bracket bolts.