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Discussion Starter · #1 ·
Hello all,

I know this topic has been covered throughly and I think I've read all the posts. But I didn't see an answer to my question. I just bought at 1988 Catalina 27 with a Universal Diesel. I had the engine serviced prior to bringing it home today (in 40 degree weather!) and the mechanic pulled the plate off the Sherwood Raw Water Pump and checked the parts and replaced the water side gasket (paper). He also pointed out that the shaft had a ringed indention an inch or so up the engine side. He said that was wear that might need to be replaced in the future. While testing the engine we started seeing raw water coming out near weep hole. It was a decent amount coming out. But I needed to underway so I headed out and got the boat home and now I am deciding what to do.

From what I read here, if it is raw water, it is the from gasket (paper) and also I understand that the Sherwood is isn't popular and most seem to prefer Oberdorfer for a replacement.

So my question- Was the mechanic correct that the ringed indention on the shaft was wear and should be replaced or could it be that he just didn't replace the gasket correctly? I've looked a as many schematics with all the parts identified and I thought I saw one that actually had the ringed indention. If this helps my water pump is the older six-screw-plate edition, which is another mystery because this is an '86.
 

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Which Universal diesel? They made a lot of different models in '86...

I will guess that it is probably an M25. If so; without hesitation, I would simply buy a new Oberdorfer from Depco Pumps in Sarasota, FL. They only cost around $250, and you can quit screwing around with a pump that you don't trust.

Regarding the ringed indentation; it is hard to say without you posting a picture so that we can offer opinions. There are grooves cut in the impeller shaft for various bits, and there can be wear marks at various other places from lack of lubrication, galvanic corrosion, or simple wear. We can't make a diagnosis without seeing the patient.
 

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If you're talking about an Atomic 4, yes, he was right. And, I highly recommend Oberdorfer, they're top quality and will last forever if properly maintained. However, they are very expensive from nearly every source I've found. That groove the machanic saw was where the "O" ring rests against the shaft. You can replace the shaft alone, but it's not an easy job and may not solve the problem.

Good Luck,

Gary :cool:
 

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With all due respect to Gary, replacing the shaft in either the Oberdorfer or Sherwood pumps on an M25/M18/M30 is EXTREMELY easy.

Here is an exploded diagram of the Sherwood pump;


All that you have to do is pull the impeller out WITHOUT removing the C-clip. The shaft and impeller will both slide out of the pump body. To replace, slide the shaft back into the pump body, then twist while applying light inward pressure. When the groove and the slot line up, the shaft will slide into, and engage with the cam shaft, and will fully into the pump.

BTW - this works the same way with the Oberdorfer pump.
 

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While I am at it, here is the diagram of the Oberdorfer pump.



The engines listed in my post above, use the N202M-15
 

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Discussion Starter · #9 · (Edited)
Thanks all. This is a picture of the engine. Can anyone tell me which Universal it is? I know one of you said M25. But I want to be certain so I can get the right replacement. I am going to go ahead and put in a new Oberdorfer from Depco Pumps. I'll post a pic of the shaft so you can see the indentions when I take it apart.

I can just tell this boat is going to be a barrel of monkeys. Apparently the bilge pump and A/C panel is a mess too. You all will be hearing a lot from me, but that is all part of the fun!

Note- For some reason when I uploaded the pic it flipped it on it's side. The right side of the pic is actually the bottom. So the pump in question is in the bottom right. Not sure why that occured.
 

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That is an M25 with the upgraded alternator mounting bracket, and the hot water bypass installed. It also seems to have an oil leak at the crankshaft seal.
 
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Also, do not load pix to SailNet from your phone. Sailnet hosting software does weird things to attachments. Insyead use a picture hosting service, like photobucket, and use links.
 
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Finally, because I know you'll eeventually ask, it is based on a Kubota D850 block.
 
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Ive lived with a sherwood pump for a decade now. Th only thing that likely needs replacement is the lip seal. Measure the shaft and the opening it fits into and buy a seal from bearints direct or another online seal source. They can be found for just a buck or two. I use the tc type seals with two lips. The lip is in a slightly different location so the groove probably wont line up with the contact area of the seal. Sherwood wants $18 for the seal for mine. I can get a handful of seals for that much online. They seem to last longer than the sherwood seals too.
 

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After having a new Sherwood pump last just 150 hours, I switched to an Oberdorfer. When you take the Sherwood apart, the reason for the short life is obvious. Despite most of the pump bring bronze, a significant area of cast iron is exposed to salt water. The shaft seals see all the resulting corrosion products.

The Oberdorfer, as well as being a better design, is about half the price right now and the impeller is much easier to change.
 

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I think my comments about the Sherwood pump life apply to the G908, the pump that superseded the G5 in the diagram earlier in the thread. They are now $433 on the interweb! Makes the Oberdorfer look cheap ($250)!
 

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Discussion Starter · #20 ·
A quick update: I ordered the Oberdorfer pump for Depco and am awaiting the part in the mail. I'll post a pic when I get it installed. It looks to be a relatively simple install. One note: The boat was a donation boat and came "as-is". The museum came across the engine manuals this week and shipped them my way. Apparently according to the paperwork the engine is a M-18, which appears to be a similar, yet underpowered M25.

One question on the crank shaft leak- Is it possible that the oil staining on the bottom half of the engine was from an old leak? The area is completely dry and there is no oil coming out of it at all. And besides the water pump issue, runs great.
 
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