The Buckshot Racing #77 Mercury V6 Water Tube lineup is designed for compatible 2.0L, 2.4L, and 2.5L two-stroke outboards using the smaller-diameter copper cooling tube Mercury engine builders commonly call the “small tube” or “1/2-inch water tube.”
The water tube carries cooling water from the lower-unit water pump up through the midsection and into the powerhead cooling system. A tube that is bent, corroded, kinked, incorrectly cut, or poorly seated can reduce water delivery and contribute to weak cooling flow, unstable water pressure, overheating, or difficult lower-unit installation.
Buckshot Racing #77 offers dedicated water-tube options for 12-inch, cut 15-inch, 20-inch, and 25-inch Mercury midsections.
Fits Mercury 2.0L, 2.4L & 2.5L V6 Two-Strokes
These small-diameter copper water tubes are used across many classic Mercury V6 engine families, including compatible 135, 150, 175, and 200 HP two-stroke outboards.
Common applications include Black Max, XR2, XR4, XR6, XRi, Laser EFI, and 220 Laser, along with other Mercury and Mariner 2.0L, 2.4L, and 2.5L V6 combinations using the correct small-tube cooling system.
Because many older Mercury engines have been rebuilt with different midsections, exhaust adapters, or gearcases, tube length should be matched to the actual midsection and cooling configuration, not horsepower or engine decal alone.
Option 1 – Mercury 12" Mid Water Tube - Mercury OEM 32-57456
The 12-inch midsection water tube is intended for compatible short-mid Mercury applications using the 1/2-inch small-tube cooling system.
This tube corresponds to Mercury OEM part number 32-57456 and is useful for short-mid rebuilds, restorations, and SST-140 or early F1 with small-tube housing on the SSM #6 / Mark 6.
Option 2 – Cut 15" Mid Sections Water Tube
The 15-inch water tube is cut for compatible Mercury 15-inch midsections using the same small-diameter copper cooling tube.
This option is useful for performance and custom Mercury V6 applications built around a 15-inch midsection.
A properly cut tube helps avoid problems caused by trimming a longer tube inaccurately, including poor water-pump engagement, excessive insertion depth, misalignment, or damage during lower-unit installation.
Option 3 – Mercury 20" Mid Water Tube - Mercury 32-8590971 Superseded by 8M0042788
The 20-inch midsection water tube is one of the most common versions used on classic Mercury V6 outboards. It replaces Mercury 32-8590971, which was later superseded by 8M0042788.
This tube is used on many compatible 2.0L, 2.4L, and 2.5L V6 engines equipped with a 20-inch midsection, including numerous 135, 150, 175, and 200 HP Black Max, XR4, XR6, XRi, Laser EFI, and similar Mercury V6 applications.
Customers searching by either the older 32-8590971 number or the later 8M0042788 number can use this option where the 20-inch small-tube configuration is required.
Option 4 – Mercury 25" Mid Water Tube - Mercury 32-8590972 Superseded by 8M0042790
The 25-inch midsection water tube is designed for compatible extra-long-shaft Mercury V6 applications. It replaces Mercury 32-8590972, superseded by 8M0042790.
This tube is used on compatible 25-inch midsection versions of Mercury 2.0L, 2.4L, and 2.5L V6 two-strokes where the small-diameter cooling tube is specified.
As with the 20-inch version, confirm the actual midsection length and tube diameter before ordering.
Why Water Tube Condition Matters
The water tube is a simple component, but it is critical to the cooling system. Common problems include dented tube ends, corrosion, kinks, incorrect length, damaged seals, or a tube that misses the water-pump guide during lower-unit installation.
A partially engaged tube can sometimes still produce telltale flow while reducing total cooling-water volume, so the tube should be inspected whenever the lower unit is removed.
Buckshot Racing #77 Installation Tech Tip
When installing the lower unit, make sure the water tube enters the water-pump guide and outlet seal squarely. Do not force the lower unit upward if the tube is not aligned.
Inspect both ends of the tube for dents, flattening, corrosion, or sharp edges. Replace hardened or damaged water-tube seals and grommets at the same time.
For cut or custom midsection applications, verify tube length before final assembly. The tube must engage securely at both ends without bottoming out or placing side-load on the water-pump housing.
The Buckshot Racing #77 Mercury Small-Tube Water Tube options:
1. 12" Early SST-140, F1 Mids – Mercury 32-57456
2. 15" Modified or Cut Mids
3. 20" Mid – Mercury 32-8590971 / 8M0042788
4. 25" Mid – Mercury 32-8590972 / 8M0042790
Optional:
- Small Water Tube Seal Grommet, Mercury OEM part 38970 and 86027
These tubes are ideal for rebuilding, restoring, or servicing compatible Mercury 2.0L, 2.4L, and 2.5L V6 two-stroke outboards using the familiar 1/2-inch small-tube cooling system.
Contact Mike Hill with technical questions at 714-697-1716