M25XPB Water pump replacement – Sherwood vs Oberdorfer

Catalina 36 - M25XPB with Oberdorfer N202M-908
Catalina 36 - M25XPB with Oberdorfer N202M-908

Since day 1 we own the boat, the sherwood water pump was leaking a bit, it was never the top issue but always something bothering me. In this article we are going to go through:

  1. Replacing the water pump
  2. Replacing one of the old cooling hose
  3. Touch up painting of the engine oil crankcase

It took few hours to go through this work, but everything was pretty straight forward.

Original state of Hotel Catalina

Here couple of pictures from June 2016, 2 weeks after we took delivery of Hotel Catalina.

First engine picture June 2016
First engine picture June 2016
First engine picture June 2016
First engine picture June 2016

Based on this pictures we can saw this leak has been there for a while by the rust we can see on the engine.

Time to fix this leak and give some love to the engine!

It has been now over 1 year we own the boat and it’s time to tackle this pump leaking and clean the rust on the engine block.

Here are few of the options to complete this task:

  • get a rebuilt kit and fixing it (tried it, it was worse!)
  • new sherwood pump (very expensive and not so much good feedback on the different forums)
  • migrate (upgrade?) to Oberdorfer
    • Replacing with an Oberdorfer pump that has the base that goes on with the same clip system as your Sherwood pump (more expensive, but more straight forward replacement)
    • If you aren’t scared of, rework the base of the Oberdorfer bolt on pump so it bolts into the pump land on the engine (way cheaper, but a bit too involved in my mind)

After looking online I found a very good deal on the N202M-908 at pump and parts online. Let’s go with this solution!

Oberdorfer N202M-908
Oberdorfer N202M-908

Here is the invoice for the pump:

Replacing the elbow water pump hose

This step is unrelated to the water pump, but it was way easier to complete since the water pump was not in the way anymore.

Old sherwood pump, old hose and old clamp. Everything will be soon replaced.

Tried to clean and fix the sherwood water pump, but the leak was always there.
Tried to clean and fix the sherwood water pump, but the leak was always there.

New hose installed!

Now time to fill the radiator with new coolant! Last time was replaced was last year during the heat exchanger failure.

Now the hose has been replaced, let’s replace the water pump!

The service from https://www.pumpsandpartsonline.com/about-us was very good! Few days after the order I received the part as expected.

I was not sure about the purpose of this hole, and asked online I realized it was to make sure in case of leak of the pump, the raw water has a way to exit somewhere else than in the engine.
I was not sure about the purpose of this hole, and asked online I realized it was to make sure in case of leak of the pump, the raw water has a way to exit somewhere else than in the engine.

Now it’s time for some painting touch up

It’s the first time I try that, I decided to pick white to be able to see if any leak happens in the future. The result is pretty good looking. Next time I have a chance to remove the belt, I will definitely do more painting.

Pump installed and running!

 

 

Temperature is good!

Impeller replacement for my spare kit

https://www.ebay.com/itm/112455220825

Oberdorfer replacement impeller
Oberdorfer replacement impeller

 

v-berth insert fix

0

The Catalina 36 V berth is laid out with one large V shaped cushion and a separate insert to fill in the Vee area attached to an upholstered board that fits/rests perfectly onto the trim of the berth. Invariably, just as we become fast asleep, the insert falls to the cabin sole. Since our plan is to sleep on the v-berth to enjoy the nice custom mattress who came with the boat, it’s time to fix it!

The solution was to put some velcro tape:

I had to staple the velcro tape against the insert (update: so far after 5 months it still hold perfectly to the v-berth).

   

Ressources

high water bilge pump switch replacement

On the way back from Catalina, it’s time to clean the boat after 4 days to the island. I check the bilge and realize a bit of water is there, pull up the switch to run the pump and nothing happen!

 

 

Corroded wires, after some troubleshooting and wiring the pump to by pass the switch, I was sure the issue was the switch.

 

Quick run to West Marine and I found the pump, of course $20 more expensive than what you can get on amazon, it was for me the first chance to try their new deal to match online price. And it works great!

Few minutes later the new switch was plugged! It’s pretty well done and you can keep the same base, so it’s really plug and play.

Seakamp 200420 zinc replacement

0

Any idea what is the zinc matching the Seakamp 200420 heat exchanger?

Seakamp just replied to me ​”¼  npt thread zinc is 1.7 inch”

Checking on the catalina36.org association, I got recommended size E0 from this site.

They also have a page for the kind you screw into the brass cap – but you may have to cut that to length.

Anyway I had to cut to the length even the E0, as soon as it was inserted the water was not able to go through anymore.

 

Engine high temperature water alarm issue

0

After the over heating issue we had last month, the water temperature alarm stopped to work. No sound anymore at the start of the engine.

After some troubleshooting it seems it was just a ground issue at the engine block level.

The wire with a resistor broke at one point and it seems to be the culprit for this issue

Ordered some 1K Ohm 1/2W Flameproof resistors:

  • https://www.amazon.com/gp/product/B000AYIQRA/ref=oh_aui_detailpage_o03_s01?ie=UTF8&psc=1

Rebuilt it and it works great now!

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