rebuilding Oberdorfer Pump
I am going to rebuild the Oberdorfer 202M-15 pump on my M25XP Universal. The pump kit comes with a carbon bushing that shattered when I removed the old one. Does anyone have experiance rebuilding this pump? I assume if I try and press it it will shatter, and I assume that I may need to Heat the pump body in the oven and freeze the bushing.
Anyone have experiance with this pump, or thoughts on it?
I wasn't aware of the carbon bushing when we did mine. I guess it wasn't loose. been about 2 years now.
I can't help you with rebuilding. If you need parts or a new pump, I recently ordered from this place:
Flange Mount Bronze Impeller Pumps
I bought a complete pump for $211 or so and a rebuild kit too.
This is the same Oberdorfer pump that is used on an Atomic 4. The folks at Moyer Marine Inc (MMI) know all about this pump Moyer Marine Atomic 4 Engine Rebuilding and Parts
and the rebuild kits and are actually really great on the phone, IMHO.
Another place to look is on their forum using the search function for 'Oberdorfer' or 'water pump': Moyer Marine Atomic 4 Community - Powered by vBulletin
Their prices for parts etc. may not be as competitive as E-discountmarine.com but they will speak to you on the phone and good customer service is a rarity these days, especially from someone who actually knows what they are talking about.
Full Disclosure: I am a satisfied customer of MMI only and do not in any way work for the company. My Atomic 4 is 42 years old and still kicking over mostly because of MMI and my PO's and my own maintenance.
I rebuilt mine as well fairly easy job do the whole gig, shaft bushing oil, water seals and shaft. she'll last a good long while. Of course new impeller and gasket........getting the bushing out would be easiest with a press but I used a socket and a BFH.....getting the new one in was a matter of a smaller hammer and a block of hardwood.
I also used a socket and a BFH to remove the old bushing, but I froze the new bushing and used a socket and a small hydraulic jack in a doorway in the basement to press it in, the seals went easy.
I have a 1982 2GM that is till raw water cooled. Have toyed with the idea of changing it to fresh water, but a few thing have kept me from doing it
1. cost. hate to spend $500 + on parts, when I may get a new engine in a few years, if anything big goes on this one.
2. Temperature - it has ran for 25 years at 130 degrees. Although diesels work better at 180 degrees, I am not sure it would like the change after all these years???
3. Not sure what pump to use. I thought I read that the rubber impellers (in raw water pumps) are damaged, or swell up, from antifreeze (when preparing for winter). Canm someone shed some light on whether it's best to get a new pump for the raw water (and use the old one for antifeeze) or vice-versa. if so, what type / model pump would be a good choice? I can't tell by pics which are shaft driven, and which can have a pulley on them!
4. where to find a heat exchanger. How to size one? Or, would an oil cooler work?
The best price I could find on my Oberdorfer pump was Depco pump co. I think it was less than 200.00 dollars.
My experience, and a few references
In the hope that this helps someone else...
I wanted to remove the impeller on my new-to-me Universal MX25 with an Oberdorfer pump for winter storage. I removed the cover plate, and there she was. In order to more easily reach the impeller, I used a small set of pliers to pull the impeller out. Unfortunately, I didn't notice the small C clip that held the impeller to the shaft:hammer. The impeller AND the shaft pulled out nicely.
I was then confronted with the problem of separating the shaft from the impeller without the use of the C clip tool, which was at home and not on the boat. I was also concerned that the shaft removed so easily. I thought that I had previously read here, that the shaft was press fitted to the bearings. Mine simply slid out.
First thing first; remove C clip. Available tools; several screwdrivers, a ball peen hammer, several hacksaw blades, channel lock pliers, and a socket set.... I tried using a slotted screwdriver to first see if I could push the clip to expand it, and then finagle it off; no dice. Then, I tried to pry the clip off with a screwdriver. This met with limited success - I broke the clip, but removed the impeller from the shaft. How expensive could a little stainless C clip be? Answer: $6.
[EDIT] April 7, 2016 - I read somewhere in the past that this "C" clip was only installed to prevent the shaft from slipping out of the pump during shipping, and IS NOT NEEDED WHEN THE PUMP IS INSTALLED. For this season I will run the pump without the clip, and post back if it is, or is not needed based on my experience.
Now to replace the shaft; fortunately, it simply slid back into the pump, and I was able to easily realign the tang in the impeller shaft with the slot in the gear shaft. I was suspicious, because I remembered something about making a tool, and press fitting, in the link above. It seemed to me that this was far too easy.
Therefore, I looked carefully at the pump housing to see if the seals were OK. I noticed that the pump was not painted, but then again, neither was the front (aluminum) cover of this engine.
I had long ago surmised that this engine had had an old style alternator bracket, which had cracked the engine timing cover, and concluded that both the timing cover, and the water pump must have been replaced by the previous owner. One of the first things that I did after acquiring the vessel, was to replace the alternator mounting bracket, and the alternator. For more about that project, and why it's important, look here.
Back to the water pump housing, I noticed a VERY small green stain near the weep hole. "The water seal must be leaking," I concluded, and decided to rebuild the whole pump. I am now not convinced that this diagnosis was accurate, but I now have the parts should the need arise.
After I drove home, I looked through Depco's catalog, which you can find here, and concluded that I had a Oberdorfer 202-15. But was puzzled by the fact that they offered 4 different rebuild kits. I also recalled from my trip to the boat that the pump did not have a paper gasket, as shown below, but rather a rubber O ring, set into a groove in the pump housing.
- Credit image from Ron Hill's Tech Note posted at c34.org
HERE is why Depco offers 4 versions of the rebuild kit: Oberdorfer has a NEW style pump, which is why Depco uses an N prefix for the rebuild kits. The new style uses an O-ring, which is set into a groove on the fact of the pump body instead of the paper gasket (#3 in the above illustration) on a flat pump body face. The other difference is that one kit is a minor rebuild kit (impeller, clip, and gasket / O-ring), while the other is a major rebuild kit (impeller, clip, gasket / O-ring, cover plate, screws, drain plug, graphite bearing, water and oil seal). Neither kit includes the shaft.
Because I tend to be thorough (my wife has another word...), I ordered the major rebuild kit (N202M-15MJK), a shaft (8767), and an extra snap ring, aka. C-Clip (5373).
Just now, in the basement I looked carefully at the parts. I tried placing the shaft through the carbon bushing just to see how tight the tolerances were. It slid through easily. Then I tried the shaft through the lip-seals (#10 in the above drawing). This was tighter, but in no way required a press.
Here is what I learned about the M202-15 raw water pump;
I believe that I may have ordered the major kit, when I didn't need it. However I will have it should the need arise.
I hope that this helps someone else learn from my mistakes. :o
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