Confusion about what Oberdorfer Pump to Use

May 2, 2012
276
Catalina 310 Toronto, Ontario
I was reading the article about replacing the Sherwood with the Oberdorfer Pump.

Within the topic thread it was mentioned that a Oberdorfer N203M-16 pump be used. Then further on in the thread it is mentioned to use the
[FONT=&quot]Oberdorfer N202M-16.

Could this be clarified. Which is it. :confused:

Cheers
2 Old Pirates

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Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
Could you provide a link to "the article" --- there have been many.

You could also noodle around the www.depcopump.com site and find out the differences between the two. IIRC, the bodies and baseplates are the same, the only difference might be the faceplates: one has an O ring, the other a paper gasket, both will work.
 
Feb 20, 2013
48
Catalina 310 Channel Islands Harbor
My pump just arrived in the mail. I bought the n202m-16 and it has the o ring.
Now I just need to trim the base to fit. Good luck this should be a big improvement.
 
Mar 22, 2009
360
Catalina 310 Gulfport Small Craft Harbor, MS
"Trim the base"...sounds a lot simpler when you say those words then what it looked like when I got it. I didn't have tools or skills to "trim the base"...which is quite thick...to fit onto the engine.

So I returned it and bought a new Sherwood which went on extremely easy. And works great.

But I do agree that it is much easier to check and change out the impeller on the Oberdorfer...but I can live with the Sherwood.

Just something to think about.

Cheers,
Jim
 
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
It was my previous post that contains a typo that makes this confusing (http://forums.sbo.sailboatowners.com/showthread.php?t=139566&highlight=sherwood&page=2). Sorry.

The correct pump for the engine in the Catalina 310 (MX-25PBC) [I don't know if this applies to the MX-25PB but is suspect it does] is the Oberdorfer N202M-16.

The N202M-15 and N202M-16 are the same pump but with different female threaded openings to connect the hose barbs to. The N202M-15 has 0.375-18 FNPT and the N202M-16 has 0.500-14 FNPT. If you make the error I did and use the N202M-15 you will need to add additional fittings and bushings to make the connections work. This adds more weak points in the system and a messy looking install. So the N202M-16 is the better choice.

As far as the modifications to the base go, all you need is an angle grinder, drill and bench vise. The brass base cuts very easily with the angle grinder. It took me less than 20 minutes to modify the pump and I am no gear head.

Sorry my previous post added some confusion to the process.

Good luck and fair winds,

Jesse
 
Feb 20, 2013
48
Catalina 310 Channel Islands Harbor
There seems to be a lot of confusion about the pumps. The front case/accessory section of our motors -mx25xpbC- is more similiar if not the same as the the m-35 series engines.
This is the difference from ours, to those used in the early C-34s, and I think that this has caused some of the issues here.

I purchased the correct gasket for the pump mount from a Kubota dealer and will use that as a template to "trim the base and adjust the bolt hole position". Will update the results here.

Big thanks to Jesse for posting his project, after reading his blog I feel confident I can do this.

Jeff
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
Stu, does that also apply to the M25-xpb?
Thanks for your continued help.
I don't personally know, since our C34s had M25, M25XPs, then M30s and M35s. Only one guy I know of 1,800 hulls has an M25XPB and that's 'cuz he replaced his original M25XP engine with it after over 5,000 hours, and kept the Sherwood that came with it, since sold the boat to his son, sorry no pictures available. What I suggest you do is go to the www.depcopump.com website and check the dimensions of the pump bases.
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada

KZW

.
May 17, 2014
831
Catalina 310 #307 Bluewater Bay, FL
My pump just arrived in the mail. I bought the n202m-16 and it has the o ring.
Now I just need to trim the base to fit. Good luck this should be a big improvement.
I have a C-310 and remain confused about trimming the Oberdorfer. Please take a lot of pictures and post them here!!!
 

KZW

.
May 17, 2014
831
Catalina 310 #307 Bluewater Bay, FL
I want a new emoticon:

:pLEASE read the blinkin' links:

Please, please, please.
I've read all the links. I still find it confusing for installation in the C-310
- Which Oberdorfer (is the gasket or O-ring better)
- Is the grinding really required (some say yes, some say no)

Maybe I'm just slow, but it just is not clear to me.
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
I've read all the links. I still find it confusing for installation in the C-310
- Which Oberdorfer (is the gasket or O-ring better)
- Is the grinding really required (some say yes, some say no)

Maybe I'm just slow, but it just is not clear to me.
The "N" series pumps have the O ring, the straight 202 series have the paper gaskets. It simply doesn't matter. The advantage of the N series is that you can turn the faceplate over since it's the same on both sides. Your pump, your choice. My straight series has worked just fine for many, many years.

If you go up to one of my earlier posts, you'll see. If you have an M25xpB, then reread Smitty's writeup, 'cuz I think that's what engine he has. The Depco Pump website has links to the Oberdorfer website so you can look at the dimensions.

Good luck, it can be confusing.
 
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
The "N" series pumps have the O ring, the straight 202 series have the paper gaskets. It simply doesn't matter. The advantage of the N series is that you can turn the faceplate over since it's the same on both sides. Your pump, your choice. My straight series has worked just fine for many, many years.

If you go up to one of my earlier posts, you'll see. If you have an M25xpB, then reread Smitty's writeup, 'cuz I think that's what engine he has. The Depco Pump website has links to the Oberdorfer website so you can look at the dimensions.

Good luck, it can be confusing.
Yup. That is my engine.

As far as the base trimming, look at the photo I attached (it was also included in the other post I did). The part marked by the black sharpie has to be trimmed off for the pump to fit flush on the motor. The two bolt holes were elongated. I did a pencil rubbing of the engine and cut out the area where the pump sits to make a template.

Again, it took about 20 minutes and I used an angle grinder and drill.

Good luck,

Jesse
 

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May 2, 2012
276
Catalina 310 Toronto, Ontario
So the M-25XPB uses the Oberdorfer N202M-16 with no alterations. Is this correct?

It seems when you start getting into different models and sizes of Catalinas it all goes hay wire.:eek:

Cheers
2 Old Pirates

Thanks for the feed back guys your the best.:D