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Old 05-04-2015, 09:27 AM   #1
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Cummins year 2001 330 hp B series water pump

My question is when do you need to replace your gear driven water pump as part of a preventative maintenance program? Mine is coming up on 3000 hours. I'm wanting to prevent an on the water break down. But I don't want to replace equipment earlier than necessary. Any solid advice?
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Old 05-04-2015, 09:51 AM   #2
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You are on borrowed time

The useful life for the Sherwood pump is around 800hrs. If the seals fail internally and take out the bearings, you run a chance of damaging your timing gears. IF YOUR PUMP IS DRIPPING WATER BETWEEN THE OUTER BEARING AND THE TWO INNER BEARINGS YOU NEED TO ACT NOW. Here are some pictures of a Sherwood pump that was in service when I took it out. The brown ground up dirt looking stuff is one of the bearings. This pump had 700 hrs on it in salt water.
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Old 05-04-2015, 10:37 AM   #3
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There are several things that can take out your R/W pump: impeller, cam, bearing and seal and all can be inspected. If you replace the impeller, the cam profile doesn't look worn, the bearings are free with no slop and the seal isn't leaking I would leave it alone.

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Old 05-04-2015, 11:18 AM   #4
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I have the exact same engine...same vintage. I just preventatively replaced both Sherwood pumps with SMX pumps. If you have 3000 hours on your current pumps I would say you definitely got your money's worth and I would replace them right now with SMX pumps. I think the design "flaw" in the Sherwood pump is the seal and spline(sp). So much so that my local Cummins dealer recommends replacing the entire pump when it is time to replace the impeller. He says that the stress put on the shaft while pulling the impeller unseats the seal and causes it to leak. His reason is based on actual experience. Tha last line was his personal opinion. But it is based on the fact that a large number of pumps begin leaking after impeller replacement....draw your own conclusion. He also says Tony's SMX pump is improved in this area and the reason it is a much better pump....not to mention the pump clears the engine mount which eliminates the need to jack up the engine to replace the pump.

PS...I would somewhat agree with David if you had 5 or 700 hours on your pump. But 3000???? That might be a record for these pumps.
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Old 05-04-2015, 11:39 AM   #5
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Assuming you do have Sherwood pumps installed....I agree with Baker. Also....the Sherwood is designed to indicate wear by dripping through a slot you can clearly see in Scary's 3rd photo at post #2. Are one or both of your pumps dripping? If not, still worth replacing at least one pump with an SMX pump and keeping the non-dripping Sherwood as an emergency spare for when (not if) the other Sherwood packs it in. But replace both if you can manage it.


Link to SMX pumps....which you can order online...is: SMX 1730 Cummins Seawater Pump - Direct Sherwood Replacement on most early 6BTA & all B & C series Diamonds


You will find an interesting write-up at that site on the failings of the Sherwood pump and the risks it poses to your engine & wallet
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Old 05-04-2015, 01:26 PM   #6
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I appreciate all of the reply's. I agree with replacement. I have been looking at the SMX pump as an upgrade. Sounds like sooner than later. Thank you for taking the time to help me out. It is great to have a place to ask questions and not feel like you have to reinvent the wheel with every issue. Not that boats ever have issues! Thanks again..😎
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Old 05-04-2015, 01:43 PM   #7
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My experience with the Sherwoods is that engines that run often, they seem to hold up ok. When sitting, the graphite/ceramic seal sticks, then the shaft spins inside the seal assembly. Then it leaks and it is all downhill from there.

The one on my Cummins lasted 10yrs and about 2500hrs before it died. I would put the SMX on but my custom motor mount that I am so proud of has a clearance issue with the longer pump.

I put a used takeout sherwood on that had a known good seal, it has been fine for about 400hrs.

If your sherwoods are not leaking, there is little risk of sudden catastrophic failure. Replace as soon as you see leak. The SMX is the way to go at that point.
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Old 05-04-2015, 05:01 PM   #8
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Quote:
Originally Posted by Baker View Post
....not to mention the pump clears the engine mount which eliminates the need to jack up the engine to replace the pump.

.
I just replaced my Sherwood pump with the SMX pump this weekend.

What a pain in the ass!!!

You still have to add a spacer or machine the arm that connects to the motor mount in order to avoid having to jack up the engine in the future.
If you only install the new pump and don't add the spacer or machine the arm, you'll still have to jack up the engine for future replacement of the pump........at least for my 5.9 6BTA Cummins. maybe it's different for other boats
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Old 05-04-2015, 06:59 PM   #9
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The pump in the picture had been leaking for a month or so. The twin on the engine was not leaking but looked close to same when disassembled. I bought the boat with 300hrs on the engines. Changed the impellers at 400hrs and these impellers had 300hrs or so. One of the few warts on the 4788 Bayliner is access to the outboard side of the engines. That combined with removing the engine mount to remove the water pump made this a dockside job that tended to get put off.
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Old 05-05-2015, 09:40 AM   #10
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Indeed it is a strange phenomenon that high use Sherwood pumps last longer. Drying of the ceramic seal on low use engines has always been my guess.
Frequent inspection of the drain hole will reveal when trouble is near. Any water or rust sign and it needs replacement.
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