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
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?
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.
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.
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. :wink:
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
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.
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
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.
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?
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
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.
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.
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
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.
Ain't this list wonderful? The price keeps falling with each message! Please keep them coming. Did you notice on the MPS site that the same pump sold under the Westerbeke name is $320.00?
I just called my diesel repair guy and he indicated that in his experience the shaft is almost always scored and needs replacing as part of the rebuild. He thought that the total cost of the rebuild with labour would be around $200 which makes the complete replacement of the pump a brilliant alternative. I have had friends try to replace the lip seals on their own with unhappy results (they break the new lip seal) so this is a job I have usually left to an expert.
In answer to Roc's question, I have just over 1000 hours on my engine. I am getting rust around the weep holes on the pump but no dripping as yet so i think I am catching this early enough. In my experience, the lip seal closest to the pump seems to go first and there is no indication that the seal on the engine side is compromised.
Earlier posts also raised the differences in water volume pumped by the Oberdorfer and Sherwood pumps. I agree that this is not likely to be a problem. I have had a few experiences with weed partially plugging the raw water intake. Even after motoring for some time with significantly reduced water flow the temperature has remained rock solid at 160 degrees.
Finally, on the mechanical seal issue. A friend replaced the lip seals on his Yanmar raw water pump with mechanical seals which apparently operate like tiny versions of the PSS shaft seal and do not therefore cause scoring of the shaft. I was simply wondering if such seals were available for this pump. I see no evidence that they are from the information found on the various web sites.
Hello all, I would just like to take time to thank both Ken Juul for the referral and Jack Hutteball for his purchase. Today when Jack called he mentioned to me that he found our site through this website. If I can ever do anything to help anyone associated with this site please let me know.
Sincerely,
Miguel Martinez
Toll free 1-866-388-0390
Stu,
I just read your reply above, which included a quote from me. The lip seals in an Oberdorfer are not carbon. They are made of brass, rubber, and an internal spring holding things together. The "carbon" referred to in some parts diagrams is a carbon bearing, which is between the outer lip seal and the impeller. In my experience, the lip seals have to be replaced twice before the carbon bearing needs replacing. The lip seals and the carbon bearing have to be press fitted into the body of the pump, but this is easy to do with a bench vice and a few pieces of scrap wood. Hope this helps.
Thanks, Tom, sorry to misquote you. Guess I should have looked at the diagram myself! :D
I noticed no change in temp when we switched out the Sherwood for the Obendorfer, and the Obendorfer is so much easier to check and change the impeller.
Guys : The purpose of the carbon bearing/bushing is to keep the shaft centered between the lip seals and the impeller in its housing/cavity of the pump body. The only damage that is usually inflected on that carbon bushing is not wear, but chipping it while changing out the lip seals (voice of experience!)!!
If you make a tool like I suggested in a MainSheet Tech notes for removing the old lip seals, you can preclude damaging that bushing!!
A thought :thumb:
I started this thread back in November 2007 and replaced my sherwood pump shortly thereafter with a new one. So here we are with just 125 hours on the new pump and it is leaking AGAIN. Seems like one should expect better performance than that out of new equipment. This is the 3rd pump on the M35B engine with a total of 533 hours on it. Maybe my engine is just a pump eater. Time to switch to an Oberdorfer? Do they have a better performance record? :donno:
Jack
I don't know about others that have an Oberdorfer, but mine is 20 years old and I have never had any issues with it. I have about 500 hours on mine.
Steve
Steve : You're lucky and your turn is coming!! :D It's just a matter of time!!
Good going Steve. By the time you need your 3rd pump your boat will be a classic 60 year old boat. :clap
Does anyone have the part number for the Oberdorfer that fits the M35B engine? Seems like it should be a 202M or close to that. I am not shure about the 4 bolt hole mounting.
Jack
Jack - I just put on a N202M-15. It was $211.50 from Depco. I used just two stainless M6-20 bolts with lock washers in the holes that had the clamps for the Sherwood G908. I think one would have to remove the gear case cover to drill out and tap the other two holes without risking getting metal shavings in the engine. You'll also need fittings to go from the 3/8" NPT on the pump to 5/8" hose. I got mine from http://fittingsandadapters.com part number MPT-90-10-6
I'm also sure you'll remember to order a gasket with the pump. :?
No oil leaks in about twenty hours of motoring since we left Montague.
I'm going to check with Gallery Marine about a rebuild of the Sherwood as a spare.
Craig
Jack : I don't believe that there is an Oberdoffer pump that will fit either an M25XPB or an M35B. I looked into that very topic when I bought my new engine.
However to make sure call Oberdoffer and ask them. I've talked to them in the past, but don't have the telephone # handy - as I'm on the boat.