WSM Mercury 20-50 Hp Cross Flow Piston kit '72-'97, STD 100-05K, 743-5172A6

WSM Mercury 20-50 Hp Cross Flow Piston kit '72-'97, STD 100-05K, 743-5172A6

Marsoni

M251S

$86.96

Get it in 3 business days with 1 day shipping. Friday, May 29

WSM Mercury 20-50 Hp Cross Flow Piston kit '72-'97, STD 100-05K, 743-5172A6Piston Kit: Mercury 20 50 Hp Cross Flow Hp STD Only STD Size Only ITEM#: 100 05K PISTON KIT: MERCURY MARINER 20 50 HP CROSSFLOW 72 97 STANDARD OEM#: 743 5172A6, 780 9229A7 NOTE: 2. 565" BRAND: WSM FITMENTS: Make Model Year(s) Mariner ALL Mercury 2 Cyl 2. 565 Bore Cross Flow 20 1972 1979 Mercury 4 Cyl 2. 565 Bore Cross Flow 40 1989 1997 Mercury 4 Cyl 2. 565 Bore Cross Flow 50 1970 1985 NOTE: 2. 565"

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2nd time purchasing this item. The 1st one lasted 2 years, but my boat hasn't been used a lot either. The marine mechanic who replaced it for me said it was definitely time to replace it. He said it fits and works just fine. Has good water flow. As for quality and value, I'd say decent. The price is better than an OMC OEM pump. I plan on using my boat more this year, so we'll see how it holds up. I'll get it replaced at the end of the year. Ease of installation, NOT EASY. The lower unit has to be completely removed from the outboard. Some outboard are easier than others and as old as this one is, it's probably easier than some of the newer ones. I've watched a couple of videos on YouTube on how to do it and I might try to do it myself next time. It cost $360 to have it done and that's with me supplying the pump. He said it took him about 1½hours to do the job, but I was charged for 3 hours labor. Probably what the book shows. I'd buy it again and I'll try to do the job myself.

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Reviewed in the United States on March 18, 2026

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Hannah

Chelsea, US

★★★★★ 4

Decent kit. Doesn’t include all parts shown in photos.

Size: 75-250 HP

I purchased this kit to replace the impeller and necessary components on my 2006 Johnson 150HP V6 Outboard. I SPECIFICALLY ordered this kit because it showed the shift shaft seal in the photos, where other kits didn’t not. This kit DID NOT include the shift shaft seal, as pictured in the photos. All the other parts fit well. The o-rings could fit a bit better. The o-ring seal for the impeller housing was a bit of a poor fit and could be made better, but still worked when glued in. Get what you pay for, right? The parts worked and replaced what I needed. Really would’ve liked to change that shift seal while everything was apart.

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Reviewed in the United States on June 21, 2023

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Kaleigh Pipho

Dallas, US

★★★★★ 5

Good but

Size: 40-50 HP

Bought and installed about a year ago. Fit exactly right and still holding up. Would buy again.

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Reviewed in the United States on May 2, 2026

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