New Lower Unit Gearcase Seal Kit Compatible With 1984-1991 Mercury Mariner 30Hp 2-Stroke Outboard

MERCURY / MARINER 25-30HP 2-STROKE + 25 JET HP LOWER UNIT GEARCASE SEAL KIT — Comprehensive Service Kit (1984-1991):

2-STROKE PLATFORM CONTEXT:
• 2-Stroke Engine Specific (NOT 4-Stroke)
• 1984-1991 Production Era
• Includes 25 Jet HP Variant
• Per JLM Marine Authoritative Cross-Reference Research
• Distinct From Later 4-Stroke 25-30HP Engines (Use 823547 Family)
• Distinct From 30HP 2-Cyl 2.992" Bore 1994-2001 (Use 823547 Family)

OEM SUPERSESSION CHAIN:
• 804908A1 → 27-8M0089636 → 8M0149926 (Current Mercury OEM)
• Same Applications Across All Supersession Numbers

MERCURY APPLICATIONS:
• Mercury 25HP 2-Stroke Outboard (1984-1991)
• Mercury 30HP 2-Stroke Outboard (1984-1991)
• Mercury 25 Jet HP Outboard (1984-1991)

MARINER APPLICATIONS (Rebadged Mercury):
• Mariner 25HP 2-Stroke Outboard (1984-1991)
• Mariner 30HP 2-Stroke Outboard (1984-1991)
• Mariner 25 Jet HP Outboard (1984-1991)
• Same Engine Architecture as Mercury Variants

⚠️ NOT COMPATIBLE WITH:
• Mercury 25HP 4-Stroke (1998 & Later) — Use 26-823547A1/A2/A03
• Mercury 30HP 4-Stroke — Different Generation
• Mercury 30HP 2-Cyl 2.992" Bore (1994-2001) — Use 26-823547A1/A2
• Mercury 35-50HP Older Outboards (Use 26-79831A1)
• Mercury 18-25HP 1980-83 (Use 26-85090A1)
• Mercury 60-125HP 2-Stroke Outboards
• Mercury V6 / V8 Outboards
• Mercury Verado L4 / L6 (Use 26-830749A01 — Different Gearcase)
• MerCruiser Sterndrive Applications
• Yamaha / Honda / Suzuki / Tohatsu Outboards (Different Brands)

SPECIFICATIONS:
• Type: Lower Unit Gearcase Seal Kit (Comprehensive)
• Application: Mercury/Mariner 25-30HP 2-Stroke + 25 Jet HP
• Engine Type: 2-Stroke
• HP Range: 25 HP, 30 HP
• Jet Variant: 25 Jet HP Compatible
• Year Coverage: 1984-1991
• Includes: Multiple Seals, O-Rings, Gaskets, Drain Plug Gaskets
• Material: Marine-Grade Rubber Compounds
• Function: Complete Lower Unit Seal Replacement
• Condition: New

OEM PART NUMBERS:
• Mercury: 804908A1 (Earliest OEM)
• Mercury: 804908A01 (With Leading Zero)
• Mercury: 27-804908A1 (With 27- Prefix)
• Mercury: 8M0089636 (Mercury Supersession)
• Mercury: 27-8M0089636 (With 27- Prefix)
• Mercury: 27-8M0089639 (Related Supersession Variant)
• Mercury: 8M0149926 (Newer Mercury Supersession)
• Mercury: 95220A1 (Related Part Number)

KIT CONTENTS:
• Lower Unit Gear Case Gaskets
• Multiple Seals (Various Positions)
• Multiple O-Rings (Various Sizes / Positions)
• Drain Plug Gaskets
• All Standard Seals for Complete Lower Unit Overhaul

WHEN TO USE THIS KIT:
• Lower Unit Complete Rebuild
• Annual Lower Unit Service Interval
• Water in Gear Oil (White / Milky Appearance)
• Gear Oil Leaking from Prop Shaft Area
• Gear Oil Leaking from Drive Shaft Area
• Replacing Forward / Reverse Gear Thrust Bearings
• Replacing Prop Shaft Bearings
• Drive Shaft Service
• Routine Preventive Maintenance for 25-30HP 2-Stroke Lower Unit

SYMPTOMS REQUIRING SEAL KIT REPLACEMENT:
• Milky / White Gear Oil at Service Drain (Water Contamination — Looks Like Coffee with Cream)
• Gear Oil Leaking from Prop Shaft Area
• Gear Oil Leaking from Drive Shaft Area
• Failed Pressure Test During Routine Service
• Lower Unit Running Hot
• Cloudy / Discolored Gear Oil
• Loss of Lubrication
• Routine Annual Service Interval Reached

INSTALLATION:
• Step 1: Drain old gear oil completely (note color / condition)
• Step 2: Remove propeller (cotter pin, prop nut, propeller from shaft)
• Step 3: Detach lower unit from outboard's upper housing
• Step 4: Take photos and notes of disassembly order / orientation
• Step 5: Disassemble lower unit components per Mercury service manual
• Step 6: Remove all old gaskets, seals, and O-rings
• Step 7: Clean all sealing surfaces thoroughly
• Step 8: Inspect gearcase housing for damage or corrosion
• Step 9: Install new seals and O-rings with light marine grease
• Step 10: Place new gaskets onto prepared surfaces
• Step 11: Reassemble per Mercury service manual torque specs
• Step 12: Pressure test gearcase before reinstalling lower unit
• Step 13: Reinstall lower unit to outboard
• Step 14: Refill with proper Mercury Hi-Performance Gear Lubricant
• Step 15: Test forward and reverse operation

⚠️ CRITICAL — VERIFY ENGINE GENERATION:
• 25-30HP 2-Stroke 1984-1991 (This Kit)
• 25HP 4-Stroke 1998-2001 (Use 26-823547A1/A2/A03)
• 30HP 2-Cyl 2.992" Bore 1994-2001 (Use 26-823547A1/A2/A03)
• 18-25HP 1980-83 (Use 26-85090A1)
• Verify Engine Generation Before Ordering

NOTE: Verify your OEM part number 804908A1 / 8M0089636 / 8M0149926 / 95220A1 AND verify your engine is 2-Stroke from 1984-1991 era before ordering. ***This kit fits ONLY Mercury/Mariner 25-30HP 2-Stroke (including 25 Jet HP) outboards from 1984-1991.*** Different engine generations (4-Stroke, 1994+ 2.992" Bore, older 1980-83 18-25HP, etc.) use different seal kits. Replace all seals concurrently for proper lower unit longevity.