The Flush-M permanently replaces the OEM flush plug, making engine flushing quick and easy so you can spend more time on the water.

The Flush-M is specifically designed to permanently replace the OEM flush plug with the part number #22-888958001 found on late model Four Stroke Mercury Outboard Engines.

Its unique features simplify repetitive engine flushing and is a must-have for single and multiple-engine boats alike.

Flush-M is compatible with Verado, Pro XS, FourStroke, and SeaPro series engines in all HP ratings from 75HP - 450HP.

Flush-M have integrated "Seasonal Solutions' for users in both warm and freezing climates.

Flush-M significantly simplifies routine engine flushing, whilst exhibiting itself attractively on single and multiple engine boats.

Dimensions

-H: 54.82 mm
-W: 53.17 mm
-L: 43.19 mm

Flush-M FAQ's

How is Flush-M different to a Gardena?
Most noticeably, the Flush-M takes the universal practicality of a quick connect and merges it with an accurately engineered base that cams perfectly securing itself to the Mercury outboard engine cowling. This is a key feature that facilitates a watertight seal that protects the engine and wiring harness from corrosion. Some additional key differences of the Flush-M include, a larger hole for increased water flow, a conical port to sealing against the cap, and a wrench color for installation leverage.

Flush-M utilises a Gardena style connector to make our product a universal application for our customers around the world. A universal connection means customers are not forced to purchase additional uniquely engineered quick connects that cannot be sourced locally and increase the end product price.

I operate my Mercury in freshwater, why should I flush at all?
Operating in freshwater has the same risks of your engine picking up foreign material as salt water engines do. Be it dirty lake water, running through mud and weed or simply picking up sand from reversing of the shoreline. Your engine cooling passages are fractions of an inch even on larger HP models as well as the associated hardware such as thermostats and check valves are all susceptible to clogging and fouling. Flushing is a sure way of expelling any foreign matter and keeping your investment safe from overheating.

My boat has an automated flushing system, why do I need Flush-M?
Having Flush-M installed on vessels with auto-flushing is insurance against a failure of these systems. We highly recommend the redundancy Flush-M offers in these situations.

Does the Flush-M restrict water flow when flushing?
No, the narrowest part of the Flush-M water passage is larger than the diameter of the engines associated internal flushing hoses and or check valve inlet/ outlet.

Is the Flush-M durable?
The Flush-M is made in an injection mold process and has added UV inhibitors rendering the end product extremely tough and UV stable even for the full time Florida sun.

How does Flush-M differ from the OEM sealed flush plug?
Flush-M primarily expedites and makes the fresh water engine flushing procedure far easier, as it is permanent installation which uses universal hose quick connects that facilitate immediate flushing.

The Flush-M has also been engineered with a few unique features:

#1 The flush-M cap is not only aesthetic but also plugs and seals the flush port inhibiting water egress in the instance that the engines check valve has failed or fouled. *Cap is secure up to +-20PSI.

#2 Operators in freezing climates can punch out the sacrificial cap seal to facilitate drainage of residual water that could otherwise freeze and rupture internal flush hoses. This is an irreversible step which replicates the 2 vent holes in the OEM plug.

Is the Flush-M watertight?
Yes it is entirely. Flush-M comes ready to use out of the box and includes a new cowling wafer style O'ring to ensure a watertight seal. The Flush-M base and retaining tabs are the exact dimensions of the OEM plug in which it replaces, insuring a perfect watertight and firm seal.

Can I operate my engine on the Flush-M?
We recommend customers follow their operators manual and use the Flush-M in the same manner as the manual indicates to use the OEM flush port.
We prefer customers to use the Flush-M with the engine off.

My boat has multiple engines, is there sufficient space for the Flush-M and a hose between the cowlings?
Yes there is, the Flush-M has conducted all R&D on a quad engine vessel for over a year without space being an issue. We recommend using a flexible elastic hose with a on/ off valve at the quick connect for ease of use.

Another easy way to create more space is to flush the engines in sequence from the starboard most engine, trimming it up slightly creating clearance from the cowling of the next inboard engine that is at rest in the down position.

The Flush-M can be permanently installed to your engine cowling by following these simple steps:

Remove the original OEM plug from the engine cowling.
Unscrew the OEM plug from the 3/4" female hose receptacle.
Separate the OEM plug from the lanyard by rotating it in a counterclockwise rotation until free.
Fit the Flush-M to the lanyard and the ¾" female hose receptacle.
Install the Flush-M back into the engine cowling, securing it in place with a ¼ turn in a clockwise rotation.

*If required, use an 11/16th wrench on the male quick connect collar for added leverage. Do not overtighten past ¼ turn.

Your engine is now ready to be operated or flushed.
To flush, simply remove the flushing cap and attach a hose to the Flush-M utilizing the included quick connector. Refit the cap upon competition.

Mercury 150HP EFI Outboard Parts & Service Kits - 2011 to 2023