Mercury Water Pump Gasket 858524
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Mercury 858524 is a genuine OEM water pump gasket for selected MerCruiser sterndrive and Mercury/Mariner outboard applications. Mercury’s official listing says this gasket is used on MerCruiser 1, R, MR, and Alpha One sterndrives and on Mercury and Mariner 65 HP (4-cylinder) through V6 outboards with short-vane water pump impellers.
Key Features
- Genuine Mercury Marine / Quicksilver OEM part
- Part number 858524
- Mercury catalog format: 27-858524
- Water pump service gasket for selected sterndrive and outboard cooling-system applications
- Mercury recommends replacing seals and gaskets when servicing or replacing the impeller.
Engine Compatibility
This gasket is listed for MerCruiser 1, R, MR, and Alpha One sterndrives in serial range 2495186–0D469858, plus Mercury and Mariner 65 HP (4-cylinder) through V6 outboards using short-vane water pump impellers. Fitment should still be confirmed by model and serial number before ordering.
Serial Number Fitment Notice
Please confirm compatibility in the Mercury Parts Catalog using your exact engine or drive serial number before purchase. Mercury’s catalog is the safest way to verify the correct water pump parts breakdown for the application.
When This Part Needs Replacement
Replace this gasket whenever the water pump is opened for impeller service, or when the original gasket is torn, compressed, leaking, or no longer sealing properly. Mercury specifically advises changing seals and gaskets when servicing or replacing water pump impellers.
Installation Notes
Use only the exact gasket specified for the water pump assembly being serviced. This part is commonly described as the upper water pump gasket in MerCruiser Alpha applications, so exact serial-based matching matters.
Alternate / Superseded Part Numbers
- 27-858524
- Supersedes older Mercury part 27-32434 according to dealer supersession listings.
Parts Desk Insight
Water pump gaskets are small parts, but they are a smart replace-while-open item during impeller service. Using the correct OEM gasket helps keep the cooling system sealed properly after reassembly.
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.