Raw water pump corrosion on W21

[mattman]

I'm still learning my way around my first diesel (a Westerbeke 21), and the other day I caught a glimpse of what looked like corrosion buried deep in the parts of the engine that I can barely see.

So I tucked my phone in there and shot the attached photo, which shows much more corrosion than I thought. I assume this is my water pump">raw water pump, which I've been meaning to inspect just to see the impeller. When I bought the boat the zinc was completely deteriorated, and there was a fair amount of corrosion on the heat exchanger which I've mostly cleaned off.

Could someone please confirm this is indeed the raw water pump, what I might be able to do about the corrosion, and any advice for inspecting the impeller given I see no obvious way to get my hands in there to work.

This is on a Nonsuch 26.

Thanks!

[DougR]

Yep, that's the raw water pump all right. Reach in there with your articulated elbow and pull off the pump by removing the four bolts, two of which you can see in the photo and the water hoses. ( close the thru hull valve)

There is a great article about rebuilding one of these Westerbeke pumps at Compass Marine How-to on pbase.com.

DougR

[mattman]

Thanks Doug. Is this something I should move up in priority to tackle sooner rather than later? My water temps are good and there is always plenty of water in my exhaust, so I've been treating this as an "preventative" inspection when I get to it. But with all that corrosion I'm wondering if I need to bump it in front of some other tasks.

[boatpoker]

That is a form of corrosion but pretty innocuous. Think of it as more a patina.
The pump is bronze and that will wash off with a little detergent. It does however indicate a salt water leak at or near the pump. Perhaps a hose or the gasket on the impeller cover plate or if you are really unlucky ,,, the pump shaft.

You should at the very least pull that impeller and have a look at it. I always advises new boaters that impeller replacement is the very first thing they should learn. A failed $50 impeller can cost you an engine in a very few moments.

[DougR]

As boatpoker said, the external corrosion doesn't appear to be very serious, probably caused by slight weeping from the cover gasket or hose connections.

From the looks of things, the pump has been recently replaced or worked on.....
- no paint on the pump and mounting bolt, and the bolt looks like stainless, and engine builders don't usually use stainless bolts
- no corrosion around the weep holes/slots between the impellor housing and the bearing housing.... Means the seals are not leaking
- The water feed hose is 1" diameter, probably too big to fit the hose barb on the pump, and the hose clamp is seriously distorting the hose to make a water tight seal. If the upper hose and clamp is the same it could be your source of water leaks.
- Looking at it closer, it seems that an upper pump mounting bolt has come out and it's sitting on the stringer

To play it safe, change the impellor and start the season with piece of mind. No one can look at the water flow out the exhaust and say " that's 100%"..... It could be 85 % or 60%.... or ??

DougR

[mattman]

Thanks guys, I'll plan on inspecting the impeller soon in light of this. I'm going to need to find a way to get access to the pump first. Some people have recommended unbolting the starter. Any thoughts on that?

Also are tools like this useful?

https://www.westmarine.com/buy/jabsc...11_335_003_502

[DougR]

Unbolting the starter will give you more room to access the coverplate of the water pump, but it might be just as hard to unbolt the starter as it is to unbolt the pump.

The impellor puller might be overkill for this size impellor...

DougR

[jackheape]

That looks like surface corrosion. I agree with everyone else about that. I just finished going over my W21 and there are some other things you need to do besides just changing the impeller.

Check the zinc on the heat exchanger. If it is not there or corroded, you need to pull the heat exchanger. Its a bitch, but well worth it. If you are reluctant to do that at least pull one of the end caps and seee what the internal tubes look like. Don't waste your time just rodding them out with a welding rod or some such. Pull the exchanger and take it to a radiator shop and get it cleaned and pressure checked for about $100. Order new gaskets and o-rings for the exchanger ends (21A model; 21 doesn't have o-rings). You can get them direct from Westerbeke online. Make sure you are ordering them for the correct model you have, a 21 or 21A. They ARE different. While you are at it you can also put a new zinc in. And probably s new bleed valve wouldn't hurt either.

Go to NAPA and order some extra fuel filters. You can get them from Sierra as an after market replacement. If you don't already have a Racor filter installed, I suggest you put one of those in as well. The little filters that are on the engine clog up quickly.

I just did all of this and added a new alternator as well (replacement Mitsubishi was $126). New belts and hoses too.

Good luck.