Quicksilver – Idler Pulley Support Bushing | MerCruiser V8 Series | Marine-Grade Aluminum | 865193

Overview

If you’ve spent enough time around a MerCruiser engine, you know the serpentine belt system has its own voice. When everything is aligned and spinning true, the motor sounds steady and sure of itself. But when an idler support bushing starts to wear, you hear the change — a faint rasp, a wobble in the belt, a reminder that something small is affecting something big. This Mercury Marine part brings that steady rhythm back. It’s one of those simple, quiet components that restores confidence the moment you install it.

Key Features

• Idler pulley support bushing for select MerCruiser engines.
• Designed for 5.0L, 5.7L, and 6.2L General Motors–based platforms.
• Precision-machined marine-grade aluminum.
• Compatible with idler pulleys 807757T, 864625T, and 8M6500024.
• Mercury Marine part number 865193.

Engine & Boat Compatibility

• Fits MerCruiser 5.0L, 5.7L, and 6.2L sterndrive and inboard engines
• Common on cruisers, sport boats, bowriders, runabouts, and family performance boats
• Suitable for engines using serpentine belt systems
• Designed for both freshwater and saltwater boating

Performance & Practical Benefits

This small aluminum bushing plays a surprisingly important role. Once installed, the idler pulley sits perfectly centered, eliminating the slight wandering or uneven belt tracking that can lead to noise, heat, and premature belt wear. You’ll feel the difference right away — the belt moves smoother, tension stays consistent, and the overall engine tone returns to that tight, controlled hum boaters love.

The marine-grade aluminum offers strength without unnecessary bulk, resisting corrosion in ways ordinary automotive bushings simply can’t. It handles heat cycles, moisture, and vibration without deforming or seizing, which gives the pulley the stable support it needs through wide ranges of RPM.

Replacing this part also gives you the chance to inspect the serpentine belt itself. When both components are fresh and aligned, the engine feels more responsive, more predictable, and far less stressed. It’s a small maintenance job that pays off in quieter operation and smoother performance across every outing.

Why Buy OEM

Support bushings see constant motion and pressure. A poorly machined aftermarket bushing can throw off belt alignment by just a fraction of a millimeter — but that’s all it takes to create squeal, slippage, or premature bearing wear.

A Mercury Marine part is engineered with the exact bore sizing and material hardness the engine requires. It fits the pulley correctly, rotates smoothly around its mounting point, and holds its shape season after season. For something this vital to engine harmony, OEM simply makes more sense. It protects your belt, your pulleys, and ultimately, your entire accessory system.

FAQ

Q1: Which engines does this bushing fit?

It fits MerCruiser 5.0L, 5.7L, and 6.2L engines using serpentine belts.

Q2: How is this better than aftermarket bushings?

OEM machining, better aluminum blend, and perfect fitment for Mercury idler pulleys.

Q3: How do I confirm this is the right part?

Check your pulley model. If you use 807757T, 864625T, or 8M6500024, this bushing matches.

Q4: Can it be used in freshwater and saltwater?

Yes — the aluminum alloy is designed for both environments.

Q5: Is installation straightforward?

Very. Most boaters complete the job with basic tools during normal belt service.