Raw water pump

John Langford · November 20, 2007, 10:31:46 AM

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.

Miguel Martinez · November 20, 2007, 01:44:52 PM

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

Tom Soko · November 21, 2007, 12:29:17 PM

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.

Stu Jackson · November 21, 2007, 12:35:21 PM

Thanks, Tom, sorry to misquote you. Guess I should have looked at the diagram myself!

captran · November 25, 2007, 06:46:35 PM

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.

Ron Hill · June 27, 2008, 05:46:17 PM

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

Jack Hutteball · July 17, 2009, 01:10:25 PM

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?

Jack

steve stoneback · July 17, 2009, 02:03:55 PM

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

Ron Hill · July 17, 2009, 05:49:07 PM

Steve : You're lucky and your turn is coming!!

It's just a matter of time!!

Jack Hutteball · July 18, 2009, 08:07:59 AM

Good going Steve. By the time you need your 3rd pump your boat will be a classic 60 year old boat.

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

Craig Illman · July 18, 2009, 11:13:11 AM

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

Ron Hill · July 18, 2009, 06:38:48 PM

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.