21990 Aftermarket Mercruiser Cylinder Service Kit 45523, 45706A4, 77442A1, 77443 | Sawley's Select Marine Parts

🔧 Product Description

Aftermarket replacement Early Trim Cylinder Complete Service Kit - Replaces Part Number: 21990

New Recmar complete trim-cylinder service kit for early MerCruiser hydraulic cylinders using the 45523, 45706A4, 77442A1 and 77443 families.

⚙️ Key Features

• Complete overhaul package for early trim cylinders

• Services internal piston, rod and gland sealing components

• Cross-references four early MerCruiser cylinder numbers

• Designed for workshop rebuild of reusable cylinder bodies

• One kit services the specified cylinder assembly

🧰 Kit / Assembly Contents

• 1 × Piston and rod-seal service group - supplied under kit P/N 21990

• 1 × Cylinder end-cap/gland service group - supplied under kit P/N 21990

• 1 × Complete O-ring and backup-ring package - supplied under kit P/N 21990

• 1 × Internal wear and retaining component package - supplied according to kit manufacturer

🔄 Supersession & Cross Reference

OEM Supersession Chain:

• 21990 (Recmar service-kit reference) → Services MerCruiser 45523, 45706A4, 77442A1 and 77443

OEM / Related Numbers:

• 45523

• 45706A4

• 77442A1

• 77443

Aftermarket / Verified Equivalents:

• Recmar: REC21990

• Aftermarket early MerCruiser complete cylinder rebuild kit

🚤 Compatibility

Commonly used on:

• Early MerCruiser hydraulic trim-cylinder systems

Typically suits:

• Engine / Drive models:

• Trim cylinders stamped or catalogued as 45523

• Cylinder assemblies 45706A4, 77442A1 and 77443

• HP / Drive Range: Drive rating dependent

• System Type: Early MerCruiser hydraulic trim-cylinder system

• Year Range: Cylinder-number dependent

• Serial / Component Identification: Check the number stamped on the cylinder before ordering; this kit is not the later 25-87400A2 seal-only kit.

🔌 Function

The service kit renews the seals, glands and internal components required to restore hydraulic sealing and smooth movement in the matching trim cylinder.

Common signs of failure / service requirement:

• Fluid leakage around the piston rod

• Drive drifts down under load

• Cylinder binds or moves unevenly

• Internal bypass prevents full travel

• Corroded gland or damaged piston seals

📦 Condition

• New aftermarket replacement part

• Brand new

• Supplied in original or equivalent packaging