Parts for your 2017 Ford Transit-Spark plugs

2017 Ford Transit — Spark Plugs: What’s fitted and how to look after them

On a 2017 Ford Transit, spark plugs are fitted to the petrol (gasoline) engines and not used on the diesel. Ford’s 2017 Transit Owner’s Manual and Workshop Manual list spark plug inspection/replacement for the 3.7‑litre Ti‑VCT V6 and 3.5‑litre EcoBoost V6, while the 3.2‑litre Power Stroke/Duratorq diesel is documented with glow plugs and compression ignition, not spark ignition. Ford Scheduled Maintenance guidance also shows spark plug replacement intervals for the petrol variants, with different intervals by engine.

If the Transit is the 3.2‑litre diesel, spark plugs don’t apply. Diesels ignite fuel by high compression and heat rather than a timed spark, so they use glow plugs to aid cold starts. That’s why a diesel Transit won’t have spark plug leads or coils firing a spark, and why plug servicing on those models simply isn’t a thing.

For the petrol 3.7 V6 or 3.5 EcoBoost, spark plugs do the hard yakka of lighting the air–fuel mix thousands of times a minute, keeping starts crisp, idle smooth and power on tap. Over time, electrodes wear and gaps widen, which can cause misfires, rough running and higher fuel use. Ford’s maintenance schedule typically calls for earlier changes on turbo EcoBoost engines than on the naturally aspirated 3.7, so owners should follow the interval in the glovebox manual. As a guide, the EcoBoost often benefits from fresh plugs around the 90–100,000 km mark, while the 3.7 V6 can stretch further under normal conditions. High‑load or lots of short trips may justify bringing that forward.

• Watch for hard starts, hesitation under load, a shaky idle, or poorer economy — all classic signs of tired plugs.
• Use the specified Motorcraft plug type and heat range, fine‑wire iridium/platinum styles are common and usually arrive pre‑gapped.
• Work on a cool engine, keep debris out of the wells, and torque to the spec in the workshop data. Over‑tight or anti‑seize where it’s not recommended can cause dramas.
• Inspect coil‑on‑plug boots and apply a dab of dielectric grease to help prevent tracking.

Sticking with the book specs from the Ford Workshop Manual and the Owner’s Manual protects performance and keeps the 2017 Transit running sweet between services.

Technical sources referenced: Ford 2017 Transit Owner’s Manual (Maintenance and Specifications), Ford Transit Workshop Manual (Ignition System sections for 3.7L/3.5L, Glow Plug system for 3.2L diesel), Ford Scheduled Maintenance Guide for 2017 Transit petrol engines.

How often should spark plugs be changed on a 2017 Transit?

It depends on the engine. The 3.5‑litre EcoBoost generally needs plugs sooner than the 3.7‑litre V6. Many service guides put EcoBoost plugs around 90–100,000 km, while the 3.7 can go longer under normal use. Always confirm the exact interval in the owner’s manual and adjust for heavy towing, lots of idling, or dusty conditions.

What type of spark plugs does it use?

Use the exact Motorcraft specification listed for the engine. These are typically fine‑wire iridium or platinum plugs with a set heat range and gap. They’re usually pre‑gapped — avoid forcing the gap on delicate fine‑wire electrodes, and check the spec in the manual before fitting.

My Transit is a 3.2 diesel — why doesn’t it have spark plugs?

Diesels ignite fuel by compressing air until it’s hot enough for self‑ignition, so they don’t need a spark. Instead, they use glow plugs to warm the chambers for clean cold starts. That’s why spark plug servicing doesn’t apply to diesel Transits.