Double Feed Outboard Flush Muffs Round Cups 12mm Hose MMS-426
MMS-426
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Double-Feed Round Outboard Flush Muffs
Extended round cups | 12mm hose connection
A double-feed flusher with extended round rubber cups for compatible outboards whose cooling-water intakes are positioned on opposite sides of the lower leg.
Key Features
- Twin-side water feed
- Extended round rubber cups
- For 12 mm (0.47 in) water hose
- Recommended product class for engines above 30 kW / 40 HP
- For compatible lower-leg side intakes
Technical Specs
| Feed type | Double / both sides |
| Cup shape | Extended round |
| Hose size | 12 mm (0.47 in) |
| Supplier recommendation | >30 kW / 40 HP class; fit still depends on intake geometry |
| 4Boats SKU | MMS-426 |
Compatibility / Fitment Guide
These muffs are selected by intake position, cup size and water-supply connection — not by horsepower or brand alone.
| Compatible intake layout | Opposed lower-leg side intakes that can be completely enclosed by the extended round cups. The >40 HP recommendation is not proof of model fit. |
| Cup fit | Both cups must sit flat and fully cover every side intake slot. They must remain sealed when water pressure is applied; damaged, painted or unusually shaped gearcases may not seal. |
| Check for extra intakes | Not suitable by itself for nose-cone, low-water-pickup, under-cavitation-plate or other uncovered intake designs. Follow the engine manual for taping/closing additional inlets or using the specified adaptor. |
| Water supply | Connect a sound 12 mm water hose to the flusher fitting. Check the hose does not pull the cups away from the gearcase. |
| Engine operation | Do not start the engine merely because muffs are fitted. Run only if the manufacturer’s flushing procedure explicitly permits it, with the gearcase vertical, gearbox in neutral, propeller area clear and a strong continuous water supply. |
| Not for | Sterndrives or inboards unless their manual specifically permits this muff arrangement; engines with a dedicated flush-port-only procedure; frozen/damaged cups; unattended running. |
Part Number Cross Reference
| Flusher style | Double-feed extended round-cup muffs |
| Water connection | 12 mm hose |
| 4Boats SKU | MMS-426 |
No OEM engine part number is claimed. The engine owner’s manual and the physical water-intake layout determine compatibility.
Frequently Asked Questions
Will these fit every outboard?
No. Both cups must cover the complete intake pattern and the engine manual must allow muff flushing.
Can I run the engine while flushing?
Only where the engine maker’s procedure expressly allows it. Never run without visible cooling-water supply and never leave the engine unattended.
Should the propeller be removed?
For workshop running, removing the propeller is the safest approach where the manual and service procedure allow; otherwise keep the area completely clear and ensure neutral is positively selected.
Why is no tell-tale visible?
Shut down immediately. Check water pressure, cup seal, blocked tell-tale and the model-specific procedure before trying again.
Allow the engine to cool, keep people clear of moving parts and hot exhaust, and never rely on muffs that do not seal positively over all required intakes.
For the products under £150 the shipping is £6.99.
Free delivery for most items over £150.
