Mercury Mariner Driveshaft Lower Unit Oil Seal - 26-43036
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The Mercury MerCruiser Quicksilver 26-43036 is a genuine Mercury Marine OEM upper driveshaft lower-unit oil seal used in select Mercury, Mariner, and Force outboard gearcase assemblies. This seal works in the driveshaft sealing area of the lower unit, helping retain gear lubricant inside the gear housing while helping block water intrusion around the driveshaft. It is commonly serviced with the related upper driveshaft oil seal 26-43035 and used where the Mercury gearcase diagram calls for 43036 / 26-43036.
Key Features
- Genuine Mercury Marine factory OEM lower-unit oil seal.
- Mercury/MerCruiser part number: 26-43036.
- Manufacturer part number: 43036.
- GTIN/UPC: 745061149687.
- Driveshaft seal used in select Mercury/Mariner/Force gearcase assemblies.
- Approximate inside diameter: 1.045 in.
- Approximate outside diameter: 1.474 in.
- Approximate width: 0.187 in. / 3/16 in.
- Commonly associated with Mercury lower-unit gear housing seal service and related seal kit applications.
Application Compatibility
Common where-used application groups include select Mercury, Mariner, and Force outboards by serial number and gearcase configuration, including:
- 40 HP, 50 HP, 60 HP, 75 HP, 80 HP, and 90 HP 3-cylinder outboard applications where specified
- 100 HP, 115 HP, and 125 HP 4-cylinder outboard applications where specified
- Select standard and BigFoot / Command Thrust style mid-range gearcase applications
- Select lower-unit gear housing assemblies using the paired driveshaft seal arrangement with 26-43035
- Related gearcase seal kit reference: 26-43035A4, where specified by the Mercury diagram
Use this seal only where the lower-unit parts diagram specifically calls for 26-43036 / 43036.
Fitment Notice
Confirm fitment by engine serial number, gearcase model, driveshaft size, seal bore, and exact Mercury lower-unit diagram before ordering. Similar horsepower engines can use different driveshaft seals depending on gearcase housing, shaft diameter, water pump base design, and production range.
When This Part Needs Replacement
Replace this seal if water is found in the lower-unit gear lube, gear oil is leaking near the driveshaft area, the seal lip is cut or hardened, or the seal is removed during water pump base or gear housing service. It should also be replaced during lower-unit resealing when the gearcase fails a pressure or vacuum test.
Installation Notes
Inspect the driveshaft sealing surface before installing the new seal. A grooved, rusted, pitted, or worn driveshaft can damage the new seal and cause repeat water intrusion. During service, inspect the paired driveshaft seal, water pump base, shift shaft seal, propeller shaft seals, drain and vent screw gaskets, and the seal bore condition. Press the seal squarely into the bore using the correct service procedure and verify the gearcase with a pressure/vacuum test before refilling with gear lubricant.
Alternate/Superseded Part Numbers
- 26-43036 — Mercury/MerCruiser formatted part number
- 43036 — Manufacturer part number
- 26-43035 — related upper driveshaft oil seal commonly serviced with this seal
- 26-43035A4 — related lower-unit gear housing seal kit reference; verify by gearcase diagram
- Sierra 18-0522 — aftermarket cross-reference
- GLM 85170 / 85160 — aftermarket cross-reference references
- SEI 94-205-11 — aftermarket cross-reference reference
Parts Desk Insight
Driveshaft seals are part of a complete gearcase sealing system, so water in the gear oil should not be diagnosed by replacing only one seal unless the leak point has been confirmed. For best results, inspect the paired driveshaft seals, water pump base, prop shaft seals, shift shaft seal, and drain screw washers, then pressure/vacuum test the gearcase before returning it to service.
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Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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