The shim can be seen under the old gasket. Some of the fasteners can be seen under the gasket as well.

Early model 5411, 5424, & M-30 engines used a small Oberdorfer pump

It required a special shim for mounting

Universal Medalist used an Oberdorfer water pump with two mounting holes on early 5411 engines. The flange of this pump interfered with other fasteners on the engine. A shim was used between the engine and the pump to shift the position of the pump away from the engine and eliminate the interference. The pump, now positioned farther from the engine then required two adapters to lengthen the shaft.

Two different extension designs are pictured (one on the pump and one adjacent to it). Discard the old extension after the installation is complete and tested. At the bottom of the photo is the grease cup lubricator. Popularized in machines like the hit-and-miss engines of the late 18th and early 19th centuries, it requires an occasional twist to force grease onto the shaft to lubricate the pump.

Easy replacement

Yes, you are supossed to have extra parts when you're done with this job.

To replace the pump, remove both the pump and the shim. The pump shaft extensions will not be necessary. Using a new gasket, mount the new pump to the engine using the fasteners that previously held the shim to the engine.

Use the mounting holes in the pump to fasten to the engine.

The flange of the new pump fits directly onto the engine

The adapter is no longer necessary

Our replacement pump is made with a (nearly) square mounting flange compatible with the fasteners on the engine.

Assuming the female threads on your pump are the typical 3/8" female National Pipe Thread (NPT), the correct replacement pump for the 5411, 5424, and M-30 engine is our #Z2857

If you simply cannot remove the old adapter plate from your engine due to rust or corrosion, we do (as of this writing in 2022) carrry the old two hole flange water pump, our part number #Z5279.