This is a comprehensive Boom Cylinder Seal Kit designed to restore the sealing integrity of the hydraulic boom cylinder on CAT 307B, 307C, 307D, and 308C excavators. It contains all necessary seals and O-rings to prevent hydraulic fluid leakage and maintain system pressure, unlike a worn seal kit that allows fluid bypass and cylinder drift. Operators may experience slow boom movement, cylinder drift when not actively controlled, or external fluid leaks around the cylinder rod when this kit fails.
Always verify with serial number before ordering.
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Inspect mating surfaces for wear before fitting. Use torque specs from service manual. Replace gaskets and seals as a set — reusing compressed gaskets causes oil leaks. Clean all oil passages with compressed air.
Always consult the OEM service manual for model-specific torque values and procedures. WhatsApp our technical team if you need fitment guidance.
A failing boom cylinder seal kit will typically result in noticeable hydraulic fluid leaks from the cylinder rod seal or internal leakage causing cylinder drift. Continued operation with worn seals can lead to reduced hydraulic system efficiency and potential damage to the cylinder rod or bore. Operators may find the boom holding its position poorly or slowly lowering under load.
Thoroughly clean the cylinder bore and rod before installing the new seals to prevent contamination and premature wear. Ensure all seals are properly seated and lubricated with system hydraulic fluid to avoid tearing during installation.
Inspect the cylinder rod for scoring or damage, and check the hydraulic fluid for contamination when replacing the boom cylinder seal kit.