Mercury Mercruiser 4-Stroke 135HP Outboard Marine Engine Parts

(2 products)

This page is for Mercury 4-Stroke 135HP outboard engines. Use it to find compatible parts and practical service information, including maintenance tips, frequently replaced components, and troubleshooting guidance. You can also browse our 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 page to narrow results by horsepower, year range, and part category.

Browse All Mercury Parts

How to Identify Your 135HP Model

Find the serial/nameplate on the swivel bracket or clamp bracket (port or starboard). The cowl may also display “Verado 135” on applicable 4‑stroke models.
Record the full serial number and any suffixes; these determine year range, mid‑section/shaft length, and control type (mechanical vs. DTS on some Verado models).
Confirm it is a 4‑stroke: look for an oil fill cap/dipstick and “FourStroke/Verado” decals. This differentiates it from earlier 2‑stroke or Optimax 135 platforms, which use different parts.
Note rigging details that affect parts: remote vs. tiller (rare for 135), gearcase type, and propeller hub style.

Platform Overview

Mercury 135 FourStroke (L4 Verado family)

Feature	Description
Configuration	Inline‑4, supercharged EFI 4‑stroke outboard with integrated power steering on many models.
Common Models	Verado 135 L4 FourStroke (mid‑2000s era and related variants; verify by serial number).
Advantages	Quiet operation, strong mid‑range torque, smooth idle, and refined control options (some with Digital Throttle & Shift).
Notes	Parts compatibility can vary by year and rigging (DTS vs. mechanical). Cooling, anodes, and some service items are specific to the Verado L4 platform—confirm via serial number before ordering.

Routine Maintenance & Service Parts

Intervals below are general guidelines for typical recreational use. Always follow the official Mercury service manual for your exact model and operating conditions.

Item	Interval*	Remarks	Parts Link
Engine oil & filter	100 hours or annually	Use FC‑W marine oil; warm engine before draining. Replace crush washer if applicable.	Oil Filters
Gear oil (lower unit)	100 hours or annually	Inspect for water intrusion/metal fines; replace drain plug seals as needed.	Mercury Lower Unit Seal Kits
Spark plugs	100–300 hours (inspect annually)	Check gap and replace if fouled or out of spec; use the correct heat range.	Spark plug
Fuel filter / water separator	100 hours or annually	Replace more often with ethanol fuel or contaminated supply.	Fuel Filters
Water pump impeller/kit	2 seasons or 200 hours	Critical for cooling; replace sooner if stream weakens or after sand/silt use.	Mercury Water Pump Repair Kits
Anodes (sacrificial)	Inspect every 50 hours; replace when 50% depleted	Match material to water type (zinc for salt, aluminum for brackish/salt, magnesium for fresh).	Anodes
Thermostat(s)	Inspect annually; replace 2–3 years	Stuck thermostats can cause overheat or cold‑running.	Mercury Outboard Parts
Accessory/drive belt	200 hours or 2 years (inspect annually)	Check for glazing, fray, or cracking; tension per spec.	Belt

Frequently Used Parts Categories

Routine Service — Service & Maintenance Kits
Cooling System — Mercury Water Pump Repair Kits
Fuel System — Fuel Filters
Ignition / Electrical — Electrical Items, Starters, Rectifiers
Corrosion Protection — Anodes
Propulsion — Propellers
Gearcase Sealing — Mercury Lower Unit Seal Kits

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak tell‑tale or overheat alarm	Inspect intake screens for debris, test impeller condition, and verify thermostat operation.	Water pump kit, thermostat, intake screen, anodes.
Hard starting or rough idle	Check fuel quality, battery voltage, spark plug wear/gap, and replace/inspect fuel filters.	Fuel filter, spark plugs, injectors, electrical connectors.
Poor acceleration or power loss	Inspect propeller for damage/slip, verify throttle opening, and check for restricted fuel flow.	Propeller, fuel pump/filter, spark plugs.
Gearcase noise or metal in gear oil	Confirm oil level/condition, inspect for fishing line at prop shaft, pressure test for seal leaks.	Lower unit seal kit, propeller hardware, gear lube/seals.
No‑crank or low‑voltage warnings	Test battery state of charge, clean/secure grounds and terminals, inspect main fuses/relays.	Starter, rectifier/charging components, battery cables.

FAQs

Are parts interchangeable between different 135HP years or platforms?

Not always. Mercury 135 FourStroke (Verado L4) parts differ from 2‑stroke and Optimax 135 models, and even within FourStroke variations some items change by serial range and rigging (DTS vs. mechanical). Always verify by serial number.

When should the impeller be replaced?

As a rule of thumb, replace every 2 seasons or ~200 hours. Replace sooner if operating in sand/silt, if the tell‑tale weakens, or after an overheat event.

How often should gear oil be changed?

Inspect and change at least annually or every 100 hours. If water or metal is present, service seals and investigate before further use.

What information do you need to confirm part compatibility?

Please provide the full engine serial number, shaft length, control type (mechanical or DTS), and any notable rigging details. Photos of the nameplate and the part needing replacement are very helpful.

Ready to find parts by horsepower, year, and model? Browse our main Mercury catalog and use the filters to zero in on your exact 135HP FourStroke.

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.