ADAPTER AS 2395030 - Caterpillar

Introduction
Do not perform any procedure in this Special Instruction until you read this information and you understand this information.This Special Instruction describes the effects of hydraulic lock or piston to valve contact. To avoid further damage, replacement of parts is recommended.Hydraulic Lock
When a liquid is trapped in an engine cylinder on the compression stroke, hydraulic lock can occur. The liquid cannot be compressed and the liquid does not have an outlet. The force of the piston on the liquid can result in damage to the engine.Hydraulic lock has been known to cause the following damage:
Cracked piston skirt on the two-piece piston
Cracked cylinder liner
Bent connecting rod
A unit injector that is ejected from the cylinder head
Injector hold down bolt is bent or broken
Head gasket spacer plate is cracked or brokenHydraulic lock can be identified by the following conditions:
A coolant leak from the spacer plate under the cylinder head of the locked cylinder
An injector that is ejected from the locked cylinderThe injector may be partially ejected or the injector may be fully ejected. In most cases of ejected injectors, the hold-down bolts are broken.For electronic engines, the injector solenoid terminals will contact the valve cover. The contact of the terminals may generate a diagnostic for the injector. The terminals may also crack or break a hole in the valve cover. In some cases, both the spacer plate and the injector are affected. In those cases, the injector can be loosened in the bore. The injector solenoid may rotate and the solenoid can come in contact with the valve springs.For high displacement engines with two-piece pistons, hydraulic lock can crack the aluminum piston skirt without cracking the spacer plate and/or without ejecting the injector from the cylinder head. It is possible to have a cracked piston skirt without any damage that is visible outside of the cylinder. The cracks in the piston skirt may not be visible.When a hydraulic lock occurs, damage to other components in the cylinder pack can also occur. This damage may result in a catastrophic failure if corrections are not made.Piston to Valve Contact
If you suspect piston to valve contact, it is important to take action as soon as possible to prevent additional damage.Piston to valve contact can occur for a number of reasons. The following examples represent some of the most common causes of piston to valve contact.Mechanical Wear:As valve train components wear, slight changes can occur that affect the valve timing. Excessive lash can expose valve train components to shock loading, which may result in additional wear and even mechanical failure. To compensate for these slight changes due to mechanical wear, Caterpillar requires valve lash settings be measured and adjusted, refer to the Operations and Maintenance Manual.Insufficient Lash: If lash settings are too tight, valves can remain open longer, allowing the head of the valve to contact the piston at TDC.Mechanical Failure:Failure of any component within the valve train that alters when valves open, or how far the valve open can result in piston to valve