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Water Pump Replacement or Retrofit, 3/8" Oberdorfer

Part #: Z2857
New raw water pump for your Universal Diesel engines:
• 5411
• 5424
• M-12
• M-2-12
• M-18
• M-25
• M-25XP
• M-30

It replaces most Oberdorfer or Sherwood water pumps on those engines.

Includes mounting gasket.

* These engines originally used a pump with a two hole flange plus a couple of adapters. If you are retrofitting this newer pump to an earlier engine, refer to our Tech Support article below: Technical Support/Water Pump Replacement...
There are several improvements compared to earlier pumps:
• The new pump has sealed bearings which eliminate the old grease cup featured on the early pump designs for easier maintenance.
• Output is equal to pumps used on the newest of the above engine models and greater than on earlier models:9-1/2 gallons per minute at 2500 RPM and zero head
• 6-1/4 GPM at 1750 RPM and 10' head. experience better cooling when compared to an early model pump.
• An "O" ring seal on the removable back plate eliminates the old gasket that needed to be replaced every time you change the impeller.

If your engine uses an adapter plate between the engine block and the pump, simply remove that adapter plate before installing this pump.

You are likely aware that the old Universal engine company used several different pumps throughout the production of each of these engines. Functionally, all of these pumps were equivalent. Universal probably used different vendors to ensure an uninterrupted supply of pumps. It is also likely that, by using two vendors, they were able to negotiate better pricing by encouraging the vendors to bid against each other. We selected this Oberdorfer pump as it currently offers you a savings of more than $150.00 when compared to a Sherwood pump, and will give you the same long life and quality service.

Some owners have chosen to replace their Sherwood water pump with this Oberdorfer pump both because the Oberdorfer is less expensive, and because replacing the impeller on an Oberdorfer is much easier than on a Sherwood. Some modifications will be required if you are replacing a Sherwood with an Oberdorfer on an M-35 A or B. Please click this link to an article on the Catalina 34 National Association web site for extensive additional information. Decide if you are willing to do the required modifications yourself before ordering.
1) This pump is equipped with 3/8" NPT ports and a male connection on the shaft of the pump (see "More Images" below). If you require a female connection on the pump shaft, please call Catalina Direct tech support at 916/843-1971 for additional assistance.

2) NPT (National Pipe Thread) measurements are an industry standard method of measuring pipe thread sizes. It does not mean that a 3/8" NPT thread can be measured with a tape measure to be 3/8". In fact, a 3/8" female NPT thread measures a little over 1/2" with a tape measure. What is the easiest way to determine positively which size port your pump has? Purchase both a 1/2" and a 3/8" pipe nipple at a hardware store and thread them into your existing pump. Now you know for sure!

3) A very few owners of early Universal 5411 raw water cooled engines report that their engine was equipped with an aftermarket fresh water cooling system. This system had a second Sherwood pump that was different than the raw water pump. The Oberdorfer pump above will not replace the fresh water pump used on this aftermarket kit. There is no known replacement.

Technical Support

Identifying the raw water pump on Universal engines
How do I know which kit I need to  order?
Raw Water Pump Replacement for 5411, 5424, & M-30 Engines
What do I do with all of these extra parts?
Water Pump Rebuild Tips
 Helpful tips for a task that requires careful work. Never run the pump dry!
Pipe Sizes and Why They Are So Confusing
Why doesn't my 3/8" NPT fitting measure 3/8"?