Mercury 135HP 4-Stroke Outboard Marine Engine Parts

(50 products)

This page is dedicated to Mercury 4-Stroke 135HP outboard engines. Use it to find compatible parts and service guidance, including maintenance tips, common replacement items, and troubleshooting advice. You can also browse our main Mercury collection. Scroll to the bottom of this page to start browsing parts for this engine. On the collection page, use the Filter & Sort controls to narrow results by horsepower, year range, and part category/section.

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How to Identify Your 135HP Model

Locate the serial number label on the outboard’s transom bracket. This number is the most reliable way to confirm exact parts compatibility.
Read the model designation and suffixes: look for horsepower (135), any “Verado” badge, and shaft length codes (L/XL). Suffixes can also indicate control type and year.
Distinguish platforms: Verado variants are supercharged inline‑4 engines (often labeled “Verado” on the cowl), while other FourStroke versions are naturally aspirated inline‑4 EFI. Verify by serial number when in doubt.
Note rigging details that affect parts: remote vs. tiller controls, mechanical vs. DTS controls on Verado, and standard vs. counter‑rotation gearcase.

Platform Overview

Inline‑4 FourStroke EFI (Naturally Aspirated)

Feature	Description
Configuration	Inline‑4, EFI four‑stroke (non‑supercharged)
Common Models	Regional 135 FourStroke inline‑4 variants; confirm exact model by serial number
Advantages	Smooth operation, broad torque curve, straightforward maintenance
Notes	Some components differ from Verado versions; use the serial number to verify gaskets, filters, and ignition parts

Inline‑4 Verado (Supercharged)

Feature	Description
Configuration	Inline‑4, supercharged Verado four‑stroke with EFI
Common Models	135 Verado; related to higher‑output Verado L4 models
Advantages	Strong mid‑range, excellent throttle response, refined NVH
Notes	Some parts are Verado‑specific (e.g., certain fuel, cooling, and rigging components). Always confirm by serial number and cowl labeling

Routine Maintenance & Service Parts

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

Item	Interval*	Remarks	Parts Link
Engine oil + filter	Every 100 hours or annually	Use FC‑W marine oil; change filter with each oil service	Oil Filters
Gear oil (lower unit)	Every 100 hours or annually	Check for water or metal on drain plug magnet; reseal if contamination is found	Mercury Lower Unit Seal Kits
Spark plugs	Inspect at 100 hours; replace as needed	Check gap and condition; replace sooner for heavy use	Spark Plugs
Fuel filter / water‑separating filter	Every 100 hours or annually	Replace more frequently with ethanol fuel or contaminated fuel	Fuel Filters
Water pump impeller / kit	Every 2 seasons (or 100 hours in sandy/silty or saltwater use)	Replace housing if scored; weak telltale or overheat are warning signs	Mercury Water Pump Repair Kits
Anodes (sacrificial)	Inspect every 50 hours; replace when ~50% depleted	Choose alloy for water type (salt/brackish/fresh)	Anodes

Frequently Used Parts Categories

Routine Service: Service & Maintenance Kits
Cooling System: Mercury Water Pump Repair Kits
Gearcase & Seals: Mercury Lower Unit Seal Kits
Fuel System: Fuel Filters
Ignition / Electrical: Electrical Items
Propulsion: Propellers
Corrosion Protection: Anodes

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak telltale or overheat alarm	Inspect intake screens for blockage; verify impeller condition; test thermostat operation	Water pump kit, thermostat, intake screen, anodes
Poor acceleration or power loss	Check propeller for damage/cavitation; verify fuel quality and replace filters; inspect spark plugs	Propeller, fuel filter, spark plugs, fuel injectors
Hard starting or rough idle	Confirm battery voltage and connections; prime fuel system; check for air leaks and clogged filters	Battery, starter, fuel filter, primer bulb/lines, spark plugs
Gearcase noise or metal in gear oil	Drain and inspect oil; look for water intrusion (milky oil); check prop shaft for fishing line cutting seals	Lower unit seal kit, bearings, gear lube, propeller hardware

FAQs

Are parts interchangeable between different years or platforms?

Some items carry over between years, but Verado vs. non‑Verado FourStroke platforms often use different filters, gaskets, and rigging parts. Use the engine’s serial number to confirm exact fitment.

When should the water pump impeller be replaced?

As preventative maintenance, replace the impeller every two seasons (or about 100 hours in sandy or saltwater use). Replace sooner if the telltale is weak, flow is intermittent, or an overheat alarm occurs.

How often should I change lower unit gear oil?

Change gear oil every 100 hours or annually. If the drained oil appears milky or you find metal on the magnet, service seals and inspect internal components before further use.

What information helps confirm part compatibility?

Provide the engine serial number from the transom bracket, the horsepower (135), whether the engine is labeled Verado or FourStroke, shaft length (L/XL), and control type. Photos of the nameplate and the part needed are also helpful.

Ready to find parts by horsepower, year, and model? Browse the main Mercury collection and use Filter & Sort to narrow your results.

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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.