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Water Pump Replacement or Retrofit, 1/2" Oberdorfer

Part #: Z2880
New raw water pump for your 5411, M-12, M-2-12, M-18, M-25, or M-25XP Universal Diesel engine. This Oberdorfer #N202M16 pump is a direct replacement for most Oberdorfer or Sherwood water pumps on these M series engines engines. For M-35 engines, see additional information below.

Includes mounting gasket.
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.
• An "O" ring seal on the removable back plate eliminates the old gasket that needed to be replaced every time you change the impeller.
• 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

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. If you would rather not have to modify the pump, see our replacement, machined pump, part Z3936, below in "May we also suggest."
1) This pump is equipped with 1/2" National Pipe Thread (NPT) ports. Remember, a pipe thread is tapered and a 1/2" thread doesn't measure 1/2" anywhere... See the tech support article below titled "Pipe Sizes and Why They Are So Confusing for more information.

2) The drive shaft of the pump has a male connection to the engine (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.

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.

4) Universal’s "B" series engines are more powerful than earlier models. The M-35B has 20% more power than the M-35 and 56% more power than the M-25XP that it replaced. More power equals more waste heat. Late Sherwood pumps move more water than Oberdorfer pumps. That said, we have had many customers successfully retrofit Oberdorfer pumps even on "B" series engines without any issues. That makes it hard to know if the higher capacity is necessary or overkill.

If you have a smaller engine and sail in northern latitudes with colder water, you are likely to have more acceptable results with an Oberdorfer pump than if you are in warmer waters with a large engine. Keep a close eye on engine temperature after any retrofit to ensure that the new pump is up to the task. If yours is an M-35B engine, you have the most waste heat to reject and the greatest chance of overheating in adverse conditions.

Retrofitting an Oberdorfer pump to an engine that came standard with a Sherwood is always at your own risk. If you decide to try the retrofit and find the performance unacceptable, your only recourse is to purchase another Sherwood pump.
Once used, you may not return the Oberdorfer pump for performance reasons.

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 Engine
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"?