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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?
 

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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.
 

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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.
 

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Discussion Starter · #6 ·
Done

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.
 

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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?

Any thoughts?
 

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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?

Any thoughts?
Call Jim or George at Depco Pump in Clearwater. They are familiar with the pump. They also have a service department that can re-build it for you very reasonably.
 

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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;
  • The Lip-Seals do not require any special tool to insert the shaft (although I suspect that they WILL require the press to remove from the pump body).
  • This pump has evolved. The old style pump body has a flat face, and uses a paper gasket to seal the face and the impeller cover. THE NEW STYLE PUMP: Uses a different pump body, and is designed to use an O ring, rather than a paper gasket.
  • Many (most?) of these pumps have a cover that is only mountable with one side facing the impeller. The impeller and the shaft constantly wear against the cover. The replacement cover from Depco will allow you to mount the cover with either side facing the impeller. Therefore, if the replacement cover should wear to the point that it leaks, just flip it over.
  • Because the pump impeller is a common thing to go, you MUST have a C clip tool in your tool kit.

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. :eek:
 

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A very thorough analysis of the Oberdorfer 202 cooling pumps.
The only question I have is regarding the grease cap fitting. I don't see that part in the exploded diagram you attached. Does this newer 'N' model pump not have the grease cap like the older models?
I ask because I recently replaced our nearly 10 year old Oberdorfer M202 pump with a new pump sold by Moyer Marine that uses bearings for the shaft instead of the grease cap fitting. The pump I used is the MMI 502 pump shown on this page Moyer Marine Atomic 4 Engine Rebuilding and Parts
I found a lightly used one for $50.
 

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Nice post Eherlily... I got a guess about what your wife says... and it's two words with a hyphen.... :D

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).
 

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A very thorough analysis of the Oberdorfer 202 cooling pumps.
The only question I have is regarding the grease cap fitting. I don't see that part in the exploded diagram you attached. Does this newer 'N' model pump not have the grease cap like the older models?
I ask because I recently replaced our nearly 10 year old Oberdorfer M202 pump with a new pump sold by Moyer Marine that uses bearings for the shaft instead of the grease cap fitting. The pump I used is the MMI 502 pump shown on this page Moyer Marine Atomic 4 Engine Rebuilding and Parts
I found a lightly used one for $50.
The grease cap is used instead of the carbon bushing on the N202M, the N202M-03, and N202M-07. All of these pumps use a 2 bolt flange. The -03, and -07 pumps are used on the Atomic 4, and the -07 is used on the M15 diesel. The -03 is a lower capacity pump (3陆GPM vs 6陆GPM @ 1700 RPM).

The N202M-15, and N202-16 have a 5 bolt flange (but you only use 4 bolts) and use the carbon bushing instead of the grease cap. The -15 is used on the Universal M-12, M-18, M-25, M-25XP, M-30 and M-50 engines. The -16 is used on Kubota branded engines.
 

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Ok. I'm going to guess that the words SailingDog was looking for were 'anal-retentive'. Of course I'd be going out on a limb.
I'm pretty sure the MMI 502 pump I just installed on our old A4 also has carbon bushings and no grease cap.
I was surprised the first time I saw an Oberdorfer water pump attached to a diesel engine. Not any more.
 

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I plead the fifth... ;)

Ok. I'm going to guess that the words SailingDog was looking for were 'anal-retentive'. Of course I'd be going out on a limb.
I'm pretty sure the MMI 502 pump I just installed on our old A4 also has carbon bushings and no grease cap.
I was surprised the first time I saw an Oberdorfer water pump attached to a diesel engine. Not any more.
 

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I thought that he thought; "very-thorough". :)
 

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Update

OK - I've rebuilt and reinstalled the pump, and thought that you may be interested in learning from my experience.

Here is an exploded diagram of the OLD STYLE pump for reference;
Gesture Font Line Art Parallel

The NEW STYLE pump, N202M, uses a rubber O-ring in place of the paper gasket (item #3 above)

First off; despite what I suspected earlier, my pump did need rebuilding. The outer lip-seal [#8] (the one that seals the water end of the shaft) was leaking, not bad, but it needed to be fixed.:cool:

I made the tool recommended in the earlier post from a 录" allen wrench. I found that the tool was useless. :eek: Instead, I used a hammer and a 12d common nail to pound the seals out. I placed the pump engine side down on a block of wood, and pounded away. I slid the shaft out of the pump, inserted the nail, head down, into the pump, engaged the head of the nail on the top of the seal, and pounded down on the point of the nail. I kept re positioning the nail around the seal, and out it, eventually, popped. Note that if you try this, that your follow through with the hammer stroke makes all the difference.

If I were to try this again, I would make some kind of press to draw the seal out. I believe that I could do this with a piece of wood, a 4" long bolt, 3 nuts, and some washers. - Next time...

My attempts to remove these seals, with both the allen tool, and the nail, had the consequence of completely buggering the carbon bearing [#12]:mad: . Fortunately, as you know from my earlier post, I had purchased the major rebuild kit, which included one. To remove the carbon bearing, there is no way, other than to use some form of press.

I am fortunate in that my vice opens just wide enough to hold a 陆" block of wood, the pump housing, and a Craftsman 3/8" drive 16mm socket. I positioned the socket in the pump housing with one end against the bearing, and the other end sticking out of the pump housing. I positioned the block of wood in the vice, and then positioned the pump/socket against the block of wood in the vice. The socket touched the face of the jaw of the vice, and the pump housing touched the block of wood. I then tightened the vice, taking care that nothing slipped out of alignment. As the bearing slowly pushed deeper, and out of the pump housing, I needed to swap the standard 16mm socket for a deep socket.

After I had the pump body completely stripped, I cleaned the face where the cover mounts up with a file, and cleaned where the Lip-Seals sit with some steel wool. There was a fair amount of corrosion (green) in here. I then polished the areas that I used steel wool with a brass brush inserted in my dremel. Finally, to help insert the new bearings and seals, I coated the inner surfaces, and the lip seals, and the bearing with molybdenum disulfide grease.


I reassembled the pump, again using the vice as a press and various sockets to insert the new carbon bearing, and the new Lip-Seals. As I recall, a 陆" drive 3/4" socket was used to press the Lip-Seals.

Hope this helps!
 

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Two seals - one for the raw water side of the pump, and one for the engine (oil) side of the pump.

The raw water seal should be inserted as deeply into the pump body as it will go - right against the carbon bearing (bushing would be more accurate). The engine seal should be inserted just enough to fully be in the pump, but not so much that it blocks the weep hole.
 
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