Water pump replacement?

[K2MSmith]

Anyone know what type of pump this and if I can get a new one ? It likes to eat impellers ( now at $39-59 a pop ) . Also it seems to airlock pretty easily . There is some calcification which I couldn’t remove completely. If it’s not easily replaced maybe I can restore it ? I know there is a small oil leak in the shaft bearing. ( or maybe that is normal to keep it lubrcated ? ) engine is s universal 25 .

 

[Frank Langer]

Anyone know what type of pump this and if I can get a new one ? It likes to eat impellers ( now at $39-59 a pop ) . Also it seems to airlock pretty easily . There is some calcification which I couldn’t remove completely. If it’s not easily replaced maybe I can restore it ? I know there is a small oil leak in the shaft bearing. ( or maybe that is normal to keep it lubrcated ? ) engine is s universal 25 .

It is an Oberdorfer raw water pump. Replacements are readily available but are expensive. One can also buy repair kits which have the required water and oil seals. One can also buy a new plate, as they can become scored on the inside.
Although annual replacement of the impeller is often recommended, many of us find they can last several years of they are not abused.
The only lubrication, aside from raw water through the pump, is via the grease cup knobs should be kept full of grease and turned a half turn periodically to inject more grease to the inside.
Never let it run dry as that ruins the impeller quickly.
Frank

 

[K2MSmith]

It is an Oberdorfer raw water pump. Replacements are readily available but are expensive. One can also buy repair kits which have the required water and oil seals. One can also buy a new plate, as they can become scored on the inside.
Although annual replacement of the impeller is often recommended, many of us find they can last several years of they are not abused.
The only lubrication, aside from raw water through the pump, is via the grease cup knobs should be kept full of grease and turned a half turn periodically to inject more grease to the inside.
Never let it run dry as that ruins the impeller quickly.
Frank

Thanks for the info . Can you explain the “grease cup knobs” . The only other screw I saw was the one at about 45 degrees from the top which looks like a vent . Not sure how this should be set .

 

[Frank Langer]

 

[Frank Langer]

View attachment 47542

I've posted a pic of my pump, showing the grease cup on the right side. I don't see one in the pic of your pump, so perhaps yours is an older model, though my previous pump on this boat, a 1984, also had a grease cup.
I think your pump has been installed upside down, and the vent screw you asked about at 45 degrees on the right side on your pic, is normally on the bottom, and is a drain for the pump to avoid water freezing in it in the winter. You may also notice that although the pump in my pic is installed right side up, the plate in the front was mounted upside down. It was like this when I bought it, and I haven't bothered to flip it right side up.
I'm not a mechanic, so this is just what I've learned over the years.
Frank

 

[Loren Beach]

For what it's worth the Oberdorfer pump on our former M25XP engine did not have a grease cup.

 

[Alan Gomes]

If you don’t want to refurbish the pump yourself, Depco Pump in Florida is the go-to place for this kind of work. Super knowledgeable, friendly, and great customer service. They could look it over and give you a price before doing the work. Sometimes rebuilding a pump is not cost effective, but it often can be. They will let you know.

 

[bigd14]

$300 for a new pump here:

N202M-16 -- Rubber Impeller Pump

www.pumpsandpartsonline.com

I just got one for my M18 which I believe would be the same model for the M25. The difference in flow out the exhaust was significant!

 

[ConchyDug]

Doesn't Moyer Marine make a modern replacement with sealed bearings and reversible plate?

MMI flange pump – moyermarine

moyermarine.com

It's an awesome website to check out even if that isn't the part you're looking for.

 

[Prairie Schooner]

There are videos online for rebuilding these pumps. I had trouble with the graphite bearings, crushing one with the official video method. I had a machine shop press the second new bearing which they chipped slightly. Then when I pressed the shaft into that, the bearing shattered. About $80 later I decided to just buy a new pump. The rest of the rebuild was fairly straightforward. I'm fairly handy, tho I know there are people here who have done it successfully. FWIW
Jeff

 

[Pete the Cat]

If your Oberdorfer pump is going through impellers, I would look for issues in the raw water feed. Do you have a screen on the outside of the boat that is clogged? (boatyards are notorious for not removing, cleaning and painting the inside of the screen on the intake through hull--I would make sure this is done at haulout). Or do you have an obstruction that is delaying water getting to the pump so it is running dry--old hose obstruction or kink somewhere?. As has been mentioned, impellers can last a very long time (I have had them over 1000 hours) if they are kept in water. If you are not getting 200 hours out of them, something is amiss.
If the pump starts to leak at the back, it needs to be rebuilt. The Oberdorfer website has a bearing kit and a very straight forward video on how to rebuild the pump itself. I have done it and found it easy if you take your time.

 

[K2MSmith]

If your Oberdorfer pump is going through impellers, I would look for issues in the raw water feed. Do you have a screen on the outside of the boat that is clogged? (boatyards are notorious for not removing, cleaning and painting the inside of the screen on the intake through hull--I would make sure this is done at haulout). Or do you have an obstruction that is delaying water getting to the pump so it is running dry--old hose obstruction or kink somewhere?. As has been mentioned, impellers can last a very long time (I have had them over 1000 hours) if they are kept in water. If you are not getting 200 hours out of them, something is amiss.
If the pump starts to leak at the back, it needs to be rebuilt. The Oberdorfer website has a bearing kit and a very straight forward video on how to rebuild the pump itself. I have done it and found it easy if you take your time.

I’m thinking it was run dry too long when I had another clog in the heat exchanger inlet about 6 months ago. I really think I need to install a filter between the raw water filter in front of the pump. if I can find a simple inline filter that doesn’t require any complex mounting, that would be great.

 

[Pete the Cat]

I’m thinking it was run dry too long when I had another clog in the heat exchanger inlet about 6 months ago. I really think I need to install a filter between the raw water filter in front of the pump. if I can find a simple inline filter that doesn’t require any complex mounting, that would be great.

I have used plastic Vetus sea strainers (and Chinese knockoffs of the Vetus from Amazon are good quality). These need to have the top of the filter about the water line in installation--otherwise you need to go with the expensive bronze sea strainers and double clamp everything. Truthfully, I have a Vetus plastic strainer on both my boats and, on very small diesels with some sort of screen on the outside of the through hull fitting, I have never seen much of anything the pump could not chop up get caught in it-in thousands of hours in some ugly rivers. You need to make sure your boat yard removes, cleans and paints antifoul the inside of the screen on the outside of the intake on the hull.

 

[dxulander]

Bought a new pump N202M-15, not sure if folks here know:
1. The pipe 3/8 NPT to hose 5/8 elbow adapter made of bronze is impossible to find. Can find them in stainless steel, or brass, but not bronze, or none of this size. Like to replace the current ones the hoses are connected to.
2. The 2 bolts that secures the pump to the engine block, anyone have an idea how those bolts are connected and how can I also replace those? Mine are all corroded and rusted. The 4 mounting points on the water pump is 3/8 thick, and 1/4 diameter holes. I can't find any references (even in the engine manual) on how these bolts are secured to the engine block.

Nevermind, found the parts for #2.

 

[Kenneth K]

The pipe 3/8 NPT to hose 5/8 elbow adapter made of bronze is impossible to find. Can find them in stainless steel, or brass, but not bronze, or none of this size.

The Oberdorfer N202-M15 has 3/8" NPT ports, the N202-M16 has 1/2" NPT ports. Other than that, I think they are identical. Pump technical drawings used to be available at https://www.pumpsandpartsonline.com...ber-impeller-pumps-parts/rubber-impeller-pump.

Seems that bronze NPT fittings are only made in 1/2" and larger, so, yeah, the 3/8" fittings are hard to work with. You have to get creative--jam a too-large fitting into the required hose; make hose butt-splices with different size hoses; use threaded pipe nipples (in bronze, stainless, or copper) instead of barb fittings. Here is one of my "adjustments:"

 

[Kenneth K]

I have used plastic Vetus sea strainers (and Chinese knockoffs of the Vetus from Amazon are good quality). These need to have the top of the filter about the water line in installation--otherwise you need to go with the expensive bronze sea strainers and double clamp everything. Truthfully, I have a Vetus plastic strainer on both my boats and, on very small diesels with some sort of screen on the outside of the through hull fitting.

I installed a plastic strainer too (yeah, above the waterline). Couldn't see using one of the large bronze strainers in such a small engine compartment. No problems over the last several years. After installing the strainer, I modified the hull inlet to be less restrictive.

 

[Christian Williams]

What's wrong with the existing bronze fittings?

 

[Pete the Cat]

What's wrong with the existing bronze fittings?

I don't think there is anything particularly wrong with bronze fittings. I just have never really liked having any more than necessary raw water plumbing below the waterline on general principles--especially sea strainers--there is a risk. I chased a very small leak into my bilge for a couple years before finding a tiny pinhole in a bronze through hull fitting. And, now that much of the stainless and bronze is coming from China and international sources, I trust any metal less than I did in decades past.

 

[dxulander]

Thoughts around bronze to SS interactions? Found an adapter made of SS: https://www.amazon.com/Beduan-Stain...0009e97ddc&ref_=pd_gw_ci_mcx_mr_hp_atf_m&th=1

 

[dxulander]

The Oberdorfer N202-M15 has 3/8" NPT ports, the N202-M16 has 1/2" NPT ports. Other than that, I think they are identical. Pump technical drawings used to be available at https://www.pumpsandpartsonline.com...ber-impeller-pumps-parts/rubber-impeller-pump.

Seems that bronze NPT fittings are only made in 1/2" and larger, so, yeah, the 3/8" fittings are hard to work with. You have to get creative--jam a too-large fitting into the required hose; make hose butt-splices with different size hoses; use threaded pipe nipples (in bronze, stainless, or copper) instead of barb fittings. Here is one of my "adjustments:"

View attachment 47979

I bought the M-16 as well, from pumpsandpartsonline.com, fingers crossed. The M-16 pump is isn't really available anywhere else, so figures, the M-15 pump is readily available, but the adapter is not. The M-16 has bronze adapter available, but pump is basically sold no where.

Couple of the 1/2 NPT to 5/8 hose (which seems to be the current standard for water hose):

McMaster-Carr

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PTHC-5062 1/2" 90 Degree NPT Bronze Hose Barb Fitting| GROCO

GROCO PTHC-5062 1/2" NPT X 1/2" or 5/8" Hose NPT Stainless Steel Hose Barb Fitting.

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