New Lower Unit Gearcase Seal Kit Compatible With 1994-Current Mercury 115Hp 4-Cyl 4.25 Gearcase

MERCURY / MARINER / FORCE 30-125HP LOWER UNIT GEARCASE SEAL KIT — 4.25" Gearcase Comprehensive Service Kit (Current 26-43035A05 Supersession):

OEM SUPERSESSION CONTEXT:
• 26-43035A05 is the CURRENT Mercury OEM Supersession
• Replaces Earlier 26-43035A1, A2, A3, A4 Part Numbers
• Supersession Chain: A1 → A2 → A3 → A4 → 26-43035A05
• All Five Part Numbers Fit Same Applications

KEY TECHNICAL SPECIFICATIONS:
• Gearcase Diameter: 4.25" (107.95mm)
• Engine Configurations: 3-Cyl and 4-Cyl
• Engine Types: 2-Stroke AND 4-Stroke
• Comprehensive 23-Piece Kit
• Reverse Clutch: 3-Jaw AND 6-Jaw Compatible (4-Cyl 100/115/125HP)
• Serial Requirement: 4-Cyl 100/115/125HP requires 0B209468 & Newer

MERCURY APPLICATIONS:
• Mercury 30HP Outboard (1999-2001)
• Mercury 40HP Outboard (1995-2007)
• Mercury 45HP Outboard (1991-2004)
• Mercury 50HP Outboard (1991-2002, 2006-2007)
• Mercury 55HP Outboard (1991-2006)
• Mercury 60HP Outboard (1991-2007)
• Mercury 65HP Outboard (1994-1998)
• Mercury 70HP Outboard (1983, 1987-1990)
• Mercury 75HP Outboard (1987-Current)
• Mercury 80HP Outboard (1987-1990, 2005-Current)
• Mercury 90HP Outboard (1987-Current) — Most Common
• Mercury 100HP Outboard (2001-2007)
• Mercury 115HP Outboard (1994-1996, 2001-Current)
• Mercury 125HP Outboard (1997-2000, 2004-Current)

MARINER APPLICATIONS (Rebadged Mercury):
• All Mariner 30-125HP Variants Matching Mercury Year/HP Coverage
• Same Engine Architecture as Mercury Variants
• Mariner 30HP / 40HP / 45HP / 50HP / 55HP / 60HP / 65HP / 70HP / 75HP / 80HP / 90HP / 100HP / 115HP / 125HP

CHRYSLER / FORCE APPLICATIONS:
• Force 75HP Outboard (1999)
• Force 90HP Outboard (1995-1999)
• Force 120HP Outboard (1995-1999)

⚠️ NOT COMPATIBLE WITH:
• Mercury 25-30HP 2-Stroke (1984-1991) — Use 804908A1 (Different Kit)
• Mercury 25-50HP NON-Bigfoot (1994-2014) — Use 26-823547A1/A2/A03
• Mercury 18-25HP (1980-83) — Use 26-85090A1
• Mercury 35-50HP Older (1977-89) — Use 26-79831A1
• Mercury V6 / V8 Outboards — Different Lower Units
• Mercury Verado L4 / L6 (Use 26-830749A01 — 4.80" Gearcase)
• Mercury Bigfoot 4-Cyl 4-Stroke 50HP — Different Variant
• Different Gearcase Diameter (Not 4.25" / 107.95mm)
• 4-Cyl 100/115/125HP Pre-Serial 0B209468 — Earlier Variant
• MerCruiser Sterndrive Applications
• Yamaha / Honda / Suzuki / Tohatsu Outboards (Different Brands)

SPECIFICATIONS:
• Type: Lower Unit Gearcase Seal Kit (Comprehensive 23-Piece)
• Application: Mercury/Mariner/Force 30-125HP Outboards
• Gearcase Diameter: 4.25" (107.95mm)
• Engine Configurations: 3-Cyl, 4-Cyl
• Engine Types: 2-Stroke and 4-Stroke
• Year Coverage: 1983-Current (varies by application)
• Reverse Clutch: 3-Jaw and 6-Jaw Compatible
• Includes: 23 Pieces (Seals, Gaskets, O-Rings, Bushing)
• Material: Marine-Grade Rubber Compounds
• Function: Complete Lower Unit Seal Replacement
• Condition: New

OEM PART NUMBERS:
• Mercury: 26-43035A05 (CURRENT OEM)
• Mercury: 26-43035A4 (Previous Current OEM)
• Mercury: 26-43035A3 (Later Supersession)
• Mercury: 26-43035A2 (Early Supersession)
• Mercury: 26-43035A1 (Earliest OEM)

OEM SUPERSESSION CHAIN (Mercury):
• 26-43035A1 → A2 → A3 → A4 → 26-43035A05 (CURRENT OEM)

KIT CONTENTS (23-Piece Comprehensive):
• Impeller Face Plate Gasket
• Multiple Impeller Gaskets (Various Sizes)
• Drain Screw Gaskets
• Multiple O-Rings (Various Sizes / Positions)
• Oil Seals (Prop Shaft and Drive Shaft Positions)
• Water Tube Seal
• Water Tube Seal Insulator
• Bushing
• Drive Shaft Oil Seal
• Additional Required Gaskets and Seals

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 4.25" Gearcase Lower Units

SYMPTOMS REQUIRING SEAL KIT REPLACEMENT:
• Milky / Water-Contaminated Gear Oil ("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: Unbolt and detach lower unit from outboard's midsection
• Step 3: Take photos and notes of disassembly order / orientation
• Step 4: Disassemble gearcase components including bearing carrier and driveshaft
• Step 5: Remove all old seals, O-rings, and gaskets
• Step 6: Take care not to scratch any sealing surfaces
• Step 7: Thoroughly clean all mating surfaces
• Step 8: Inspect gearcase housing for damage or corrosion
• Step 9: Lubricate new seals with light coat of marine grease
• Step 10: Install new seals into respective bores ensuring proper seating
• Step 11: Install new O-rings and gaskets during reassembly
• Step 12: Reassemble gearcase per Mercury torque specifications
• Step 13: Pressure test gearcase before reinstalling lower unit
• Step 14: Reinstall lower unit onto outboard
• Step 15: Refill gearcase with recommended marine gear lubricant until flowing from upper vent hole
• Step 16: Reinstall both drain / vent screws with new gaskets
• Step 17: Check for any leaks after a short period of operation

⚠️ CRITICAL — VERIFY GEARCASE DIAMETER:
• 4.25" (107.95mm) Gearcase Diameter (This Kit)
• 3.44" (135mm) Torpedo Diameter — Use 26-823547A1/A2/A03 Series
• 4.80" Bullet Torpedo (Verado) — Use 26-830749A01
• Verify Your Specific Gearcase Diameter Before Ordering

NOTE: Verify your OEM part number 26-43035A05 / A4 / A3 / A2 / A1 AND verify your gearcase diameter is 4.25" (107.95mm) before ordering. ***This kit fits ONLY Mercury/Mariner/Force 30-125HP outboards with 4.25" gearcase diameter.*** Different gearcase diameters use different kits. 26-43035A05 supersedes earlier 26-43035A1/A2/A3/A4 part numbers — same applications all five. Replace all seals concurrently for proper lower unit longevity.