Mercury Mariner 135HP Marine Outboard Engine Parts

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This page is tailored for Mercury Mariner 2‑Stroke 135 HP outboard engines. Use it to find compatible parts and practical service information, including maintenance tips, common replacement items, and troubleshooting guidance. You can also browse the main Mercury collection. Scroll to the bottom of this page to start browsing parts for this engine, and remember you can use the Filter & Sort controls on the collection pages to narrow results by horsepower, year range, and part category.

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How to Identify Your 135 HP Model

Nameplate/serial plate: Typically on the swivel or clamp bracket. Record the full serial and any model code.
Model code suffixes: Often note shaft length, control/steering type, and revisions—useful for matching gearcase seals, impellers, and anodes.
Platform differences: Many 135 HP two‑strokes are V6 carb/EFI; later units may be V6 DFI (often marketed as OptiMax). Some ignition, fuel, and cooling parts differ between platforms.
Oil system: Most V6 two‑strokes use oil injection with a remote tank. Confirm whether your engine is oil‑injected or premix before ordering fuel/oil components.

Platform Overview

V6 Carb/EFI 2‑Stroke

Feature	Description
Configuration	V6 two‑stroke, typically carbureted (some EFI variants), common from the late 1980s through the late 1990s.
Common Models	Examples sometimes listed for 135 HP families include codes like 1135412PD and 1135425VD/WD (verify by serial range).
Advantages	Proven platform, strong mid‑range torque, and broad parts availability.
Notes	Cooling and gearcase parts often carry over across V6 families; ignition and fuel components can vary by year/serial and carb vs EFI.

V6 DFI (OptiMax) 2‑Stroke

Feature	Description
Configuration	V6 two‑stroke with direct fuel injection, most common in early‑ to mid‑2000s models.
Common Models	Example series often noted include 1135D73AD and 1135D73CD/DD (confirm by serial number).
Advantages	Better fuel economy and emissions than carb models; solid all‑around performance.
Notes	DFI‑specific parts (air/fuel rails, injectors, high‑pressure pumps) do not interchange with carb platforms. Service intervals for plugs/filters may differ.

Routine Maintenance & Service Parts

Intervals below are general guidelines for two‑stroke outboards. Always follow the official service manual for your exact serial range and conditions.

Item	Interval*	Remarks	Parts Link
Lower unit gear oil	Every 100 hours or annually	Inspect for water intrusion/metal; replace drain/fill gaskets as needed.	Mercury Outboard Parts
Spark plugs	Inspect 100 hours; replace ~200 hours or as required	Gap per spec; DFI often requires specific plug types/intervals.	Spark plugs
Fuel filter / water‑separating filter	Every 100 hours or annually	Shorten interval with ethanol fuel or contamination.	Fuel Filters
Water pump impeller / kit	Every 100 hours or annually	Service sooner for sandy/silty water or weak telltale.	Mercury Water Pump Repair Kits
Anodes (sacrificial)	Inspect every 50 hours; replace when ~50% consumed	Match material to water type: zinc, aluminum, or magnesium.	Anodes
Thermostats	Every 2 years or ~300 hours	Stuck thermostats can cause rich running or overheat alarms.	Mercury Outboard Parts
Oil injection system check	Annually	Inspect remote tank screen, lines, and pump operation; purge air after service.	Hoses
Gearcase seals (if leaks found)	As needed	Pressure/vac test if water in oil; reseal before further use.	Mercury Lower Unit Seal Kits

Frequently Used Parts Categories

Routine Service — Mercury Outboard Parts
Cooling System — Mercury Water Pump Repair Kits
Fuel System — Fuel Filters
Ignition / Electrical — Electrical Items
Gearcase / Seals — Mercury Lower Unit Seal Kits
Propellers & Hubs — Propellers
Corrosion Protection — Anodes

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak water stream / overheat alarm	Inspect intake screens, thermostat operation, and impeller condition; verify hose routing.	Water pump kit, thermostat(s), intake screen, cooling hoses
Poor acceleration / power loss	Check fuel filter and primer bulb, inspect spark plugs, confirm prop pitch/condition.	Fuel filter, spark plugs, propeller, fuel hoses
Hard starting / rough idle	Verify choke/enrichment, check for stale fuel, perform compression and spark tests.	Spark plugs, fuel filter, fuel lines, carb/DFI service components
Excessive smoke (two‑stroke)	Confirm correct oil type and injection calibration; check thermostats for stuck‑open.	Spark plugs, oil lines/tank filter, thermostats
Gearcase noise / metal in gear oil	Drain and inspect oil; pressure/vac test for seal leaks; check prop shaft for fishing line.	Lower unit seal kit, bearings, prop shaft seals

FAQs

Are parts interchangeable across different years or platforms?

Many wear items (anodes, water pump kits, seal kits) are shared across V6 135 HP models. Ignition, fuel delivery (carb vs DFI), and some cooling parts can differ by year/serial. Always verify with the full serial number.

When should the impeller be replaced?

As a baseline, service the water pump every 100 hours or annually—sooner if you run in sandy/silty water, see a weak telltale, or after any overheat event. Periodically replacing the full kit refreshes wear plate(s) and seals.

How often should lower unit gear oil be changed?

Change every 100 hours or once per season. If oil appears milky or contains metal, perform a pressure/vacuum test and reseal the gearcase before further use.

What information helps confirm parts compatibility?

Provide the engine serial number, model code, shaft length, control/steering type, and whether your 135 HP is carb/EFI or DFI. Photos of the nameplate and the part needing replacement are helpful.

Ready to find parts for your Mercury/Mariner 135 HP two‑stroke? Browse the main Mercury collection and use Filter & Sort to narrow by horsepower, year, and model.

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If you’re unsure about your model, send us a photo of the nameplate and the part you need and we’ll help verify compatibility.