Raw water pump

[Jack Hutteball]

At the risk of beating a dead horse...my Sherwood is leaking again, first at 100 hours, rebuilt, and now again at 400 hours.  This seems excessive to me, so I think it is time for a new pump not a rebuild.  That said, I have reviewed all the great information on the Sherwood vs Oberdorfer debate.  It seems it boils down to a matter of  individual preference as either pump seems interchangeable on the M35, with cost and ease of impeller replacement being the biggest variables.  I note however that most Orberdorfers seem to be on the M25 engines.  How many of you with M35 engines have replaced your Sherwood with the Orberdorfer, and has it maintained your same engine temperature (since it seems to circulate "less" water)?  I am assuming most owners with M35 engines have not had leaking as I have had and just been merrily replacing impellers and sailing happily along.
Jack

[Roc]

Jack,
My Sherwood just started leaking (minimally) for the first time, after 700 hours.  Sent it to Depco for rebuild.  You say your rebuild did not last that long?  Did it fail after only 100 hours?

[Rick Johnson]

I would be interested in that answer also.  I've replaced my leaking Sherwood with an Orberdorfer.  As everyone has said, it pumps less water but the temperature has remained at 160.  I was planning on sending the Sherwood to Depco to have it rebuilt as a spare.

[Stu Jackson]

Jack, I understand the discussion (and essentially non-issue) about water quantity, and Rick pretty much answered that one.

I believe the MOST important difference between the pumps is the ease of service, which is critical.  The Oberdorfer gets serviced from the front.  The Sherwood requires contortions if not downright removal to simply change the impeller, although I guess you could buy the quick release pump cover bolts, which cost half again what the pump itself costs.  That additional expense doesn't make too much sense to me.

It would seem reasonable to purchase something that is easier to service.

Only the 100 hours on a rebuild sounds pretty lame.  Its the seals that leak, so unless the shaft is gone, new seals should last as long as the original ones.  Somethin's weird there, but if you've already bit the bullet for a new pump, go for it.

[Ron Hill]

Jack : You didn't say where you had your pump rebuilt at?  I'd definitely trust DEPCO.
One of the chief causes for a raw water pump to leak is that the lipseal has worn a slight grove in the shaft as well as worn the lipseal itself.  When you then replace only the lip seal, it will only seal for a shorter period of time.  So a complete rebuild should also include a new shaft!! 
I also use waterproof grease on the water lipseal side to help lube the shaft.   

[Jack Hutteball]

My pump failed the first time at 100 hours.  The dealer had it rebuilt under warranty by an unknown to me, local shop.  It has now failed at an additional 300 hours.  I tend to think that the rebuild was improper or there is something inherently wrong with the pump.  I am reluctant to put out more $ for a rebuild if it will last only another 300 hours.  I noticed from a search that the shafts for the Sherwood are now hard to find or non existant.

Seems to make more sense to replace with new even though it will be more $.  Since an Oberdorfer seems to be less expensive, works just the same, and is easier to maintain, seems like the right decision.  A water pump on an automobile lasts for thousands of hours.  Hopefully a new pump will provide more trouble free hours.

Jack

[Roc]

Depco has my pump and is letting me know if it can be rebuilt.  But in earlier discussions I had with them, just inquiring the ballpark cost of a rebuild.  The labor to do it is $37.  The bearings and seals don't add up to much, maybe $100 tops.  The shaft is the most expensive at $105.

About the ease of servicing a Sherwood pump, I have no problem with it.  An offset box wrench can get to the three backward screws with no problem.  To put the impeller in, I wrap the veins (all pointed in the same direction) with a cable tie.  Then I slip it in the front housing, with the veins oriented in the proper direction.  Then the cable tie is cut.  I do this without talking the two hoses off the housing.

[Jack Hutteball]

Roc,
The price for the rebuild seems expensive, about $245 when I add your numbers.  CL Marine sells a new Sherwood for about the same price.  Am I missing something?  Are there other things that need to be purchased with a new pump?  Per Ron's post a new shaft will probably be needed.  I noticed on a previous post that Depco does not have the shaft and that you need to find one and send it to them.
Jack

[Roc]

Jack,
You are right, if you need a new shaft, a rebuild doesn't make sense.  I was saying if all that is needed is seals, etc, and other parts are still in good working order, then it might be worth it. 

[John Langford]

I am just beginning to get a tiny bit of weeping out of the drain holes on my Sherwood. It's just enough to dampen the bottom of the pump by the weep holes after an hour of motoring. How much water would you expect to see before you would contemplate replacing the lip seal?

Also, can the lip seal on a Sherwood be replaced with a mechanical seal which, I gather is less likely to score the shaft?

[Jack Hutteball]

John,
I would be interested to know how many hours you have on your engine as a comparison to mine.  The first time mine started to weep (100 hours) it went from damp to dripping in a matter of hours.  The second time (400 hours) it has been slower.  However the pump body starts to rust very quickly.  I would be concerned about letting it run down the front of the engine very long as that could cause other problems.
Jack

[Roc]

John,
If you are noticing some water coming out of the weep hole, even a very small amount, why wait to get it fixed.  It might break down completely at the worst time.  What I noticed on mine was the mounting screw had evidence of corrosion, assuming from water spraying out of the weep hole.  Then, with the engine running, I looked inside the weep hole and noticed 'bubbling/girgling' inside, which looked like water was in there, but not enough to drip out.  I have 725 hours logged on the engine.

[Stu Jackson]

John

From a discussion on Sherwood pumps from the C36 Message Board from Tom Sokoloski:

Posted Thu June 14 2007 07:27 PM

If you call up Depco Pump or another source for parts, the seals are called "lip seals", and there are two of them, both around the shaft. One to keep oil in the engine, and one to keep water in the pump. If installed backwards, they will leak very quickly (don't ask how I know!!!) You should also check the shaft for scoring. If you can see any ridges on the shaft, replace it.

During that discussion, someone asked:

"What's the best method to combat the rust?"

I responded:  The best way is to stop the rust from occurring. The way to do that is to remove the pump and either rebuild it or replace it because the leak indicates that your seals are breaking down inside the engine. Once that happens, there is the chance of mixing oil and water inside the engine, which is NOT good.  Fix the cause, not just the cosmetics.

Since we have an Oberdorfer, not a Sherwood, I'm not familiar with the particulars of that pump.  However, in earlier discussions I had with someone on the C36 board who did, we did find, online, a blow-up of the Sherwood pump.  It could well be in the Manuals section of our website, right here.  Marinedieseldirect would most likely have it, too, but it sounds like you already do have it.

In answer to your specific question about the lip seal, it appears from Tom's post above that the lip seal(s) are defined as the two inside the pump.  Since they are made of, I believe, carbon, that's about as mechanical as you can get.

In light of the lack of response to your question, I recommend calling Depco and asking them.  My recommendation about your pump is to remove it and replace the seals.  While you're at it, get another shaft as a backup so you always have a shaft with a new impeller right on it for a very quick replacement.

Also, given your description about the amount of weeping:  do it NOW because it's only gonna get worse.

[Roc]

Turns out my pump would be almost the cost of a new one.  This is the best price I could find. Depco wouldn't match the price.
http://www.pumpagents.com/SherwoodPumps/G908.html

[Ken Juul]

I got my new Sherwood here.

http://www.marinepartssource.com/product.asp?pnumber=shg903 

Currently have 12 in stock, $246.36, if I remember correctly shipping was free.