CROWN AS-PISTON 3938987 - Caterpillar

Top Deck Visual Inspection
The following inspection process should be followed carefully. Any evidence of top deck wear, fretting, corrosion, pitting, or erosion should be addressed during the repair.
Illustration 2 g03817612
Machining marks present across the entire deck including the liner seat areas. USE AS IS. NO MACHINE WORK REQUIRED
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A closer view of the machining marks still apparent in the liner seat area.USE AS IS. NO MACHINE WORK REQUIRED
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Machining marks still present in the liner seat. USE AS IS. NO MACHINE WORK REQUIRED
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This block shows witness marks 360* around the liner bore seat. No wear can be felt with a fingernail. The machining marks are still present in the lower part of the illustration.USE AS IS. NO MACHINE WORK REQUIRED
Illustration 6 g03817619
Liner seat showing corrosion pitting around the liner seat. MACHINE BLOCK BEFORE REUSING
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Fretting around the liner seat. This fretting can be felt with a fingernail. MACHINE BLOCK BEFORE REUSING
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Polishing at the top of the liner seat and fretting at the bottom. MACHINE BLOCK BEFORE REUSINGIf your cylinder block requires machining and liner seat inserts installed, see your Cat dealer. Your Cat dealer will be able to service the cylinder block bringing the cylinder back into specification.Spacer Plate Inspection
Inspection of the spacer plate is also critical. Never use a spacer plate that shows cracks. Never reuse a spacer plate gasket. Do not grind the plate to clean the spacer plate. Do not reuse spacer plates with cracks, handling damage, cleaning damage, or large amounts of corrosion/erosion.
Illustration 9 g03817738
This spacer plate has a large scratch on the left and handling damage on the right. DO NOT USE AGAIN
Illustration 10 g03812527
Spacer plate with a crack.DO NOT USE AGAIN
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This spacer plate shows imprints from the gasket. USE AGAINOther Considerations
If there has been a head gasket failure the use of new cylinder head bolts is recommended. It is impossible to know how many times a bolt has been used. All bolts yield when they are torqued. Repeated torquing of a bolt will eventually fatigue the bolt and failure of the joint will occur. Before installation, apply Loctite 5923 to both sides of the spacer plate gasket.If one cylinder requires liner seat inserts it is recommended that the other five are also machined. This will ensure the best possible result and long-term reliability of the joint.