One improvement made when the M-25XP was introduced was to add a larger, higher capacity 3" diameter heat exchanger for better cooling performance.

This replacement 3" diameter heat exchanger is a direct replacement for the original part used on the M-25XP and is an excellent retrofit upgrade for the M-25 engines as well. The same heat exchanger is also used on the M-35 series engines. This is not a direct replacement for the later B series M-25XPB and M-35B engines which uses a different model yet.

This entire assembly contains NO ferrous metal. It is about 10 pounds of bronze and copper and is hand made right here in the United States!

• Raw water hose sizes: 5/8"
• Engine water hose sizes: 7/8"
• Diameter of heat exchanger body: 3"
• Length of heat exchanger body: 13"
• Zinc: 3/8" thread, 11/16" wrench

1) Any returns must be packaged in factory's original box and expanded foam protection.

2) This item does not conform to the shipping table in the Shopping Cart. Additional shipping must be calculated. When you place your order we always call with a shipping quote before billing your card. For a quote in advance, just call 800/959-7245.

3) The original 2" X 16" used brazed on brackets on the M-25 and M-25XP. An intermediate replacement 3" X 13" used a single bracket that is no longer available and clamps, but then this version with removable set of brackets was introduced and can be used not only on the M-25 and M-25XP, but the M-35 as well.

4) Uses our replacement zinc Z2552 shown below under "May We Also Suggest".

5) Some of the early M-25s had a bracket that was fastened to the top of the bell housing and was mounted horizontally. If that is the configuration on your engine, you will need to use a 3" diameter pipe to flatten out the existing bracket to accommodate this larger diameter heat exchanger and reuse the original bracket. The new brackets included with this heat exchanger will not fasten properly to these very early M-25 engines.