Mercury - Idler Pulley - 864625T
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The Mercury MerCruiser Quicksilver Idler Pulley 864625T is an OEM serpentine belt pulley used on compatible MerCruiser V6 and V8 stern drive and inboard engines. It helps guide and maintain proper belt tracking across the accessory drive system.
Key Features
- Genuine Mercury/MerCruiser idler pulley
- Part number: 864625T
- 4.25" / 4-1/4" outside diameter
- 6-groove serpentine belt design
- Sealed bearing pulley construction
- Used on compatible Alpha and Bravo engine packages
- Helps maintain proper accessory belt alignment and tension
Engine Compatibility
Fits select 1998 and newer MerCruiser V6 and V8 marine engines, including 4.3L V6, 5.0L V8, 5.7L / 350 Mag, and 6.2L / MX 6.2L applications using this 6-groove serpentine pulley setup.
Serial Number Fitment Notice
Verify fitment by engine serial number, belt routing diagram, pulley diameter, and original pulley part number before ordering. Pulley fitment can vary by accessory bracket layout, belt system, engine model, and production range.
When This Part Needs Replacement
Replace this pulley if the bearing is noisy, rough, loose, seized, wobbling, cracked, corroded, or if the belt shows abnormal wear, squealing, tracking issues, or repeated belt failure.
Installation Notes
Inspect the serpentine belt, belt tensioner, adjacent pulleys, alternator pulley, power steering pulley, and bracket alignment during service. Replace the belt if it is glazed, cracked, frayed, oil-soaked, or worn.
Alternate/Superseded Part Numbers
Primary Mercury references: 864625T, 849296T, 57-8638764, and 57-862086. Common aftermarket interchange: Sierra Marine 18-15101.
Parts Desk Insight
A worn idler pulley can make a new belt fail quickly. If the pulley bearing feels rough or the belt is tracking off-center, replacing the pulley during belt service helps protect the full accessory drive system.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.