Mercury Quicksilver — Water Pump Impeller Washer — 8M0204722
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Mercury Quicksilver Water Pump Impeller Washer 8M0204722
Mercury Quicksilver 8M0204722 is a genuine OEM washer used in Mercury outboard water-pump and gear-housing assemblies. It is installed in the water-pump stack around the impeller and drive key and replaces earlier Mercury part number 8M0027721.
Compatible Applications
- Mercury 30 HP two-cylinder two-stroke outboards
- Mercury 40 HP two-cylinder two-stroke outboards
- Mercury 40 HP three-cylinder two-stroke outboards
- Additional Mercury gear housings whose water-pump diagram specifies 8M0204722 or superseded 8M0027721
Serial-number fitment: Confirm the engine serial number and gear-housing diagram before ordering. Mercury used different water-pump arrangements across horsepower ranges and production years.
Part Details
- Current part number: 8M0204722
- Catalog-form number: 12-8M0204722
- Brand: Mercury Quicksilver
- Product type: Water-pump impeller washer
- System: Gear-housing raw-water pump
- Supersedes: 8M0027721
- Condition: New
Key Features
- Genuine OEM water-pump component
- Installed directly beside the impeller in applicable assemblies
- Works with the impeller key, face plate, pump housing, and related gaskets
- Some diagrams specify two washers per pump, one above and one below the impeller
When to Replace This Washer
Inspect and replace the washer during impeller or water-pump service if it is worn, distorted, grooved, corroded, damaged, or missing. Inspect both washers whenever the water pump is opened, particularly after overheating, reduced cooling-water flow, or impeller failure.
Installation Notes
Install the washer in the exact order shown in the serial-specific gear-housing diagram. Many assemblies use one washer above and one below the impeller, with the drive key forming part of the same driveshaft stack. During service, inspect the impeller, key, upper housing, face plate, upper and lower gaskets, and water-tube seal. Follow the applicable service procedure for final assembly.
Technical FAQ
Is this a general-purpose flat washer?
No. It is a diagram-specific component of compatible Mercury water-pump and impeller assemblies.
How many washers are required?
Quantity varies by application. Many diagrams show two washers, one on each side of the impeller.
What earlier number does it replace?
8M0204722 supersedes Mercury part number 8M0027721.
Parts Desk Insights
Best use case: Replacing worn or missing impeller-stack washers while the lower unit is already apart for water-pump service.
Most common mistake: Reassembling the pump with only one washer when the diagram calls for one above and one below the impeller.
Fitment guidance: Match the engine serial number, gear housing, washer quantity, and stack order to the applicable water-pump diagram before installation.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 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.