Oberdorfer pump question

[2ndwish]

After reading the various threads about Oberdorfer leaks and rebuilds, I took a look at the engine. Low an behold, there was some corrosion around the weep holes and evidence on the block that it had been leaking. I decided to see how bad the leak was and ran the engine for 20 minutes under load. The weep hole was dry. We went sailing today and motored for nearly an hour. Checked again after the sail-dry again.  Its possible that the pump used to leak and was repaired, but why wouldn't the corrosion have been cleaned? Any ideas?
T

[Mike and Joanne Stimmler]

The previous owner probably never got around to it. The pump could have been repaired or replaced.  Does the pump look newer or cleaner than the surrounding area?
You should also check the oil pan for rust.
Keep an eye on it for awhile to make sure it's still not leaking.

Mike

[2ndwish]

Thanks Mike. There is a small spot of rust at the pan (1cm). The PO and 1/2 CO tells me the water pump faceplate has leaked in the past. Would that present the same symptoms (ie a little corrosion on the weep holes as well as marks on the engine)?

[Stu Jackson]

It very well could if there was enough water weeping past the faceplate gasket to run into the weep hole.  

But really, don't sweat it, Mike was right, that's the only plausible explanation.

Just clean up around the pumps carefully, and also follow ALL the rust/stain streaks, clean them up, and repaint.  I used Rustoleum after I did my cleanup up and sanded, haven't gotten around to using the engine color tan paint.  I bought a can of Westerbeke paint, but GM Camel (search this board for that and you'll find the paint #) and you should be fine.  Only you can tell how deep the rust may be, without pictures and we're simply not there on your boat with you.

If you have any questions about the integrity of the pump, and it seems you've done your homework by running it as you have so it sounds good, then take it out and redo the seals. Wouldn't hurt to learn what's all back there...  The wiki has the manuals you need to see the diagrams.

[Stu Jackson]

Here's another really good "How To":

http://www.pbase.com/mainecruising/raw_water_pump

Maine Sail's website is fantastic and a very good resource for all of us.

In addition, he's got his own "Featured Contributor" page on www.catalinaowners.com: 

http://forums.sbo.sailboatowners.com/forumdisplay.php?f=135

Scroll to the bottom to show all threads from the beginning, about 6 pages, so far...

[Ron Hill]

2nd : What you need to do is when the engine is running go below and open the starboard engine access door and shine a flashlite on the Oberdoffer and see if it's leaking. 
You need to do that periodically and then shine the light at the packing gland and see if there's anything unusual going on back there. 

A single drop of salt water will /can cause a corrosion spot- ie changing to a new impeller could leave a couple of drips if not dryed off. 

After you check the starboard side of the engine you just might want to also look at the port side of the engine thru the head engine access door - and see if all is OK there!! 

Much easier than pulling the steps to look for leaks.   A few thoughts

[2ndwish]

Thanks for all of the suggestions. We'll keep an eye on it. It appears to have been the pump faceplate which leaked in the past.
T

[Ron Hill]

2nd : The face plate leak is easy to fix with a new "paper thin" gasket !! 

[2ndwish]

UPDATE- This was a water seal after all. The leak was really intermittent. Finally figured it out after running and inspecting two days in a row. The pump would leak only after the engine was running for a while and then completely cooled down (a condition which usually occurred long after I was off the boat). In summary:
Engine cold -> no leak
Engine warm -> no leak
Engine cooling after being warm-> no leak
Engine cold the next day after running-> leak

In short trust the rust...it never sleeps

[Ron Hill]

2nd : Glad to see that your leak finally showed itself.  When to change out the lip seals make sure that you inspect the stainless drive shaft for wear and/or scoring. 

The Oberdoffer has a very narrow "seal" width and tends to wear the shaft.