Water Pump Repair Kit for Mercury/Mariner 2-Stroke 15XD, 18XD, 20XD, 25XD & 25 HP 3-Cylinder Outboards – Replaces 46-99157T2
Water Pump Repair Kit for Mercury/Mariner 2-Stroke 15XD, 18XD, 20XD, 25XD & 25 HP 3-Cylinder Outboards – Replaces 46-99157T2 is backordered and will ship as soon as it is back in stock.
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Water Pump Repair Kit for Mercury/Mariner 2-Stroke 15XD, 18XD, 20XD...
Water Pump Repair Kit for Mercury/Mariner 2-Stroke 15XD, 18XD, 20XD, 25XD & 25 HP 3-Cylinder Outboards – Replaces 46-99157T2 is backordered and will ship as soon as it is back in stock.
Product Details
This water pump repair kit with housing is designed to service the cooling system on selected Mercury and Mariner 2-stroke outboards. Catalog references identify the applicable engine group as the 15XD, 18XD, 20XD, 25XD, and 25 HP 3-cylinder models from 1984 onward. Always compare your engine model, serial number, and original pump components before ordering.
The kit is associated with the Mercury OEM reference 46-99157T2. This is an aftermarket replacement kit intended to restore water-pump performance when the original housing, impeller, gaskets, seals, or related components are worn.
- Service-style replacement for the original water pump assembly.
- Includes a pump housing and the listed service components.
- Suitable for selected Mercury and Mariner 2-stroke applications only; it is not listed here as a universal fit for all 15–25 HP engines.
Part Number Matrix
Use the following reference to compare this replacement with the number shown on your original pump component or parts catalog.
| Reference Type | Part Number |
|---|---|
| Mercury OEM | 46-99157T2 |
| Mercury related housing reference | 46-99157A02 |
| GLM catalog reference | 12014 |
Engine & Model Compatibility
The catalog relationship for 46-99157T2 identifies the following Mercury and Mariner 2-stroke engine group. The year condition shown in the catalog is 1984 and later; serial-number coverage can vary by market and production change, so verify the complete engine identification before installation.
| Brand | Model | Rated HP | Stroke | Year Condition | OEM Reference | Fitment Note |
|---|---|---|---|---|---|---|
| Mercury | 15XD | 15 | 2-Stroke | 1984 and later | 46-99157T2 | Verify serial number and original pump configuration. |
| Mercury | 18XD | 18 | 2-Stroke | 1984 and later | 46-99157T2 | Verify serial number and original pump configuration. |
| Mercury | 20XD | 20 | 2-Stroke | 1984 and later | 46-99157T2 | Verify serial number and original pump configuration. |
| Mercury | 25XD | 25 | 2-Stroke | 1984 and later | 46-99157T2 | Verify serial number and original pump configuration. |
| Mercury | 25 HP 3-cylinder | 25 | 2-Stroke | 1984 and later | 46-99157T2 | Verify serial number and original pump configuration. |
| Mariner | 15XD, 18XD, 20XD, 25XD and 25 HP 3-cylinder | 15–25 | 2-Stroke | 1984 and later | 46-99157T2 | Verify market-specific serial number and original pump configuration. |
Technical Specs
- Product Type
- Water pump repair kit with housing
- Application
- Selected Mercury and Mariner 2-stroke outboards
- Installation
- Replacement service installation
- Housing Material
- Stainless steel 316
- Housing Color
- Metallic
- Package Dimensions
- 151 × 103 × 52 mm (5.94 × 4.06 × 2.05 inches)
- Package Weight
- 0.29 kg (10.2 ounces)
- Warranty
- 1-year limited warranty
What’s in the Box
- 1 × Pump housing assembly — 99157A02, 99157A1
- 1 × Face plate — 85083
- 1 × Gasket — 993261
- 1 × Key — 8M0032838
- 1 × Seal — 85090001, 85090
- 2 × Transparent washer — 12-86645-1
- 4 × Insulator — 23-85095
- 3 × O-ring
Installation Notes
- Disconnect the battery or spark plug leads as appropriate for the engine and secure the propeller before servicing.
- Place a drain pan under the gearcase and drain the gear oil if required by the service procedure.
- Remove the fasteners securing the lower unit to the driveshaft housing.
- Lower the gearcase carefully and disconnect or move the speedometer tube if fitted.
- Remove the existing water pump housing, face plate, impeller, key, gaskets, seals, and related parts.
- Clean the mating surfaces thoroughly and remove old gasket material or debris.
- Install the new gasket, face plate, impeller, key, seal, and housing in the correct order. Lubricate the impeller with a suitable lubricant before assembly.
- Reinstall the lower unit while aligning the driveshaft, shift shaft, and water tube.
- Tighten the fasteners according to the engine manufacturer’s service procedure and refill the gearcase with the correct lubricant.
- Run the engine only in a suitable water supply and confirm a steady tell-tale stream before returning the boat to service.
Troubleshooting & FAQ
How do I confirm this kit fits my engine?
Match the engine brand, exact model, stroke, year condition, and serial number against the compatibility information. The most reliable check is to compare the original pump assembly and its OEM reference with 46-99157T2 before ordering.
Does this listing fit Mercury or Mariner 4-stroke 9.9–15 HP engines?
This listing is described for the cataloged Mercury and Mariner 2-stroke applications shown above. Do not use the 4-stroke 9.9–15 HP description from an earlier listing as confirmation of fitment.
Does this kit fit every Mercury or Mariner 15–25 HP engine?
No. Horsepower alone is not sufficient for identification. Confirm the exact model, production year, serial number, and pump configuration before installation.
What are common signs of a failing water pump?
Symptoms may include overheating at idle or low speed, a weak or missing tell-tale stream, an overheat alarm, or a damaged impeller with cracked or missing vanes.
How often should the impeller be replaced?
Inspect the impeller during routine seasonal maintenance and replace it when the service schedule, operating conditions, or visible wear indicate replacement is necessary. Saltwater, sand, and long periods of storage can accelerate wear.
Is this an OEM part?
No. This is an aftermarket replacement kit associated with the Mercury OEM reference 46-99157T2. Mercury and Mariner are referenced only for application identification.
Is everything needed for installation included?
The listed housing, face plate, gasket, key, seal, washers, insulators, and O-rings are included. You will need suitable tools, the correct service information, and fresh gearcase lubricant if the service procedure requires it.
What should I do if the engine still overheats after installation?
Stop operation and check impeller orientation, key engagement, gasket and seal seating, water-tube alignment, cooling-water intake passages, and the tell-tale outlet. If the cause is not clear, have the cooling system inspected by a qualified marine technician.
Safety & Important Information
- Confirm the exact engine model, year, serial number, stroke, and original pump configuration before purchase.
- Do not rely on horsepower alone to determine compatibility.
- This is an aftermarket replacement, not a Mercury or Mariner OEM component.
- Follow the engine manufacturer’s service instructions and use appropriate personal protective equipment.
- Professional installation is recommended if you are not experienced with outboard lower-unit or water-pump service.
About Sea Sierra
- Marine Replacement Parts — Practical aftermarket components for routine outboard maintenance and repair.
- Application-Focused Fitment — Check model and serial details before ordering to help ensure the correct replacement.
- Support for Maintenance Work — Parts are supplied for repair and service applications using the information provided on this page.
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