Mercury – Quicksilver 811635T3 Distributor Cap | GM 4-Cylinder Engines | Delco EST Ignition | 811635T3

Overview

A reliable start and a steady idle depend on a clean, consistent spark — and that begins right at the distributor. The Quicksilver 811635T3 Distributor Cap is the genuine OEM replacement for marinized GM 4-cylinder MerCruiser engines equipped with Delco EST ignition systems. It’s the same cap Mercury installs at the factory, built to withstand the heat, vibration, and moisture that come with life on the water.

This part may not look exciting, but it’s one of those quiet heroes under the engine cover. A good cap means fewer misfires, faster starts, and a smoother day on the water.

Key Features

• Purpose: Replaces worn or corroded distributor caps to maintain strong, consistent spark across all cylinders.
• Fitment: Designed for 4-cylinder MerCruiser engines by GM running Delco EST (Electronic Spark Timing) ignition systems.
• Material Quality: Molded from a PBT/PET composite that resists warping, cracking, and thermal stress under constant heat.
• Electrical Contacts: Solid brass inserts ensure steady conductivity and resist corrosion and electrical pitting.
• Design Detail: Built to reduce RFI interference, keeping marine electronics like GPS and radios clear and reliable.

Engine & Boat Compatibility

• GM-based 4-cylinder MerCruiser sterndrive engines
• Delco EST ignition systems
• Common on small runabouts, bowriders, and compact inboard/sterndrive boats

Performance & Practical Benefits

A distributor cap is a small part that makes a big difference. When your ignition system’s connections are clean and strong, you’ll notice easier starts, smoother idle, and a more responsive throttle. The 811635T3 cap keeps spark timing accurate, helping your engine deliver full power and fuel efficiency.

Mercury’s use of a PBT/PET composite means this cap won’t warp or crack when the engine compartment gets hot. The brass terminals maintain a clean, even connection through every cycle, reducing the risk of arcing or premature wear. And since it’s engineered to limit radio frequency interference, your electronics stay quiet and clear while you run.

Why Buy OEM

Mercury’s OEM ignition components are built specifically for marine conditions — they’re not rebranded automotive parts. The materials are tougher, the tolerances tighter, and every component is tested to handle salt, spray, and heat over the long haul.

Aftermarket caps might look the same but often use cheaper plastic and aluminum contacts that don’t hold up. A genuine Mercury part fits perfectly, lasts longer, and performs exactly as the engine’s ignition system was designed to. It’s about doing the job once and knowing it’s done right.

FAQ

Q1: What engines does the Quicksilver 811635T3 fit?
A: It’s made for 4-cylinder MerCruiser engines built by General Motors that use Delco EST ignition systems.

Q2: What’s included in this part?
A: This kit includes the distributor cap only — the rotor is sold separately.

Q3: Can it be used in saltwater?
A: Yes. The brass terminals and composite housing resist corrosion in both salt and freshwater environments.

Q4: Will it affect onboard electronics?
A: No. It’s designed to prevent RFI interference, keeping radios and navigation systems clear.

Q5: How often should it be replaced?
A: Inspect the cap annually and replace it every 100 hours or as needed if you see corrosion, cracks, or misfiring.