MerCruiser 4-Stroke 135HP Marine Engine Parts

(23 products)

This page supports Mercury 4‑Stroke 135HP outboard engines and helps you quickly find compatible parts and service information. Inside you’ll find maintenance tips, common replacement parts, and troubleshooting guidance. You can also browse the main Mercury collection. Scroll down 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.

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How to Identify Your 135HP Model

Locate the engine serial number/nameplate on the transom bracket or swivel bracket. A duplicate label may be under the cowling.
Read the model designation and suffix: codes typically indicate shaft length (L/XL), steering/controls, and other options. Record any suffix letters for accurate parts selection.
Confirm platform: most 135HP Mercury 4‑strokes are inline‑four EFI engines, including L4 Verado variants. Cowl decals and the serial plate will help you distinguish the exact family.
Note build year/serial range from the under‑cowl emissions label; this is useful when parts changed across production updates.

Platform Overview

Inline‑4 EFI 4‑Stroke (includes L4 Verado variants)

Feature	Description
Configuration	Inline‑4, EFI 4‑stroke outboard platform. Some models are L4 Verado variants known for smooth operation and strong mid‑range pull.
Common Models	135HP FourStroke inline‑four; 135 L4 Verado (inline‑four) variants.
Advantages	Refined running quality, responsive throttle, good fuel economy, and broad parts availability across the inline‑four family.
Notes	Many routine service items are shared across 135–200HP inline‑four families, but always confirm by serial number and model suffix before ordering.

Routine Maintenance & Service Parts

Intervals below are general guidelines for typical recreational use. Always follow the official service manual for your specific serial number range and operating conditions.

Item	Interval*	Remarks	Parts Link
Engine oil + filter	Every 100 hours or annually	Warm engine before draining; replace crush washer if applicable.	Shop Oil Filters
Gear oil (lower unit)	Every 100 hours or annually	Change sooner if water intrusion, metal on magnet, or heavy use.	Mercury Outboard Parts
Spark plugs	Inspect at 100 hours; replace as needed or per manual	Check gap and look for fouling; replace all plugs as a set.	Shop Spark Plugs
Fuel filter / water separator	Inspect every 50–100 hours; replace at least annually	Replace sooner if poor fuel quality or performance complaints.	Shop Fuel Filters
Water pump impeller / kit	Every 2–3 seasons or 300 hours (annually in sandy/silty waters)	Essential for cooling; replace immediately if stream is weak or uneven.	Mercury Water Pump Repair Kits
Anodes (corrosion protection)	Inspect every 3 months; replace when 50% consumed	Use the correct material for your water (aluminum, zinc, or magnesium).	Shop Anodes
Serpentine/drive belt (where equipped)	Inspect at 100 hours; replace ~300 hours or per manual	Look for cracks, glazing, or noise; tensioner condition matters.	Shop Belts

Frequently Used Parts Categories

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

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak tell‑tale stream or overheat alarm	Inspect intake screens for blockage, verify water pump condition, check thermostats.	Water pump impeller/kit, thermostat, intake screen grommets
Poor acceleration or power loss	Confirm fresh fuel, replace/inspect fuel filters, check spark plugs, inspect prop for damage.	Fuel filter, spark plugs, propeller
Hard starting or rough idle	Verify battery voltage and cable connections, check plugs, inspect for air leaks on fuel side.	Spark plugs, fuel filter, electrical connectors
Gearcase noise or metal in gear oil	Drain and inspect gear oil; look for water intrusion; check prop shaft for fishing line.	Lower unit seal kit, bearings, propeller hub

FAQs

Are parts interchangeable between different years or inline‑four platforms?

Many routine items (filters, anodes, some pump kits) are shared across 135–200HP inline‑four families, including certain L4 Verado variants. Always verify by serial number and model suffix to ensure correct fit.

When should I replace the impeller?

As a rule of thumb, replace the water pump impeller every 2–3 seasons or ~300 hours, and sooner if operating in sandy/silty water or if the tell‑tale stream weakens.

How often should gear oil be changed?

Change gear oil at least every 100 hours or annually. Inspect sooner if you notice milky oil, metal on the drain plug magnet, or after an impact/grounding event.

What information helps confirm part compatibility?

Provide the engine serial number, model designation (including suffix letters), approximate model year, shaft length (L/XL), and any notable options. Photos of the nameplate and the part being replaced are also helpful.

Ready to find parts by horsepower, year, and model? Browse the main Mercury collection to locate components that match your 135HP inline‑four.

Shop Mercury Outboard Parts

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.