Reply
 
Thread Tools Search this Thread Display Modes
 
Old 04-08-2017, 02:46 PM   #1
Veteran Member
 
City: New Bern, NC
Country: US
Vessel Name: Miss Deb
Vessel Model: Nordic Tug 37
Join Date: Sep 2014
Posts: 63
Raw Water Pump Impeller Replacement

This really should not be that difficult but then again I've been wrong before. PLEASE OFFER SUGGESTIONS!

First time changing the raw water impeller on our 6BTA5.9. It still has the Sherwood pump.

Got the old impeller out okay and the new impeller is in . . .. almost.

The impeller vanes are slightly proud of the sealing face of the pump and if I dry fit the Speedseal cover it rocks slightly.

I have the original pump cover and bolts and found a hard rubber disk that is app. the same size as the impeller hub. Stuck the rubber disk to the center of the old cover using a dab of grease, put it against the impeller hub and then used the bolts to try and drive the impeller the last fraction of inch onto the shaft.

Took the bolts to dead tight, removed them and the impeller had not budged. Still slightly proud of the sealing surface.

What's next??

Thanks,

Gene
__________________
Advertisement

SlowsailNC is offline   Reply With Quote
Old 04-08-2017, 04:06 PM   #2
Guru
 
LarryM's Avatar
 
City: League City, TX
Country: USA
Vessel Name: Pelago
Vessel Model: Wellcraft 3300 Coastal
Join Date: Aug 2011
Posts: 923
If you don't already have it, download the Sherwood 17000 Pump Series Technical Guide where you will find a clear breakdown of the pump and complete instructions for rebuilding it.

I guess the first question I have is if the impellers are the same width. That rubber disk is called an impeller cap and should fit into a recess in the impeller. In some models it prevents the key from damaging the cover plate.

Is this a genuine Sherwood 17000 impeller? If so it sounds like either the impeller or wear plate are not seating completely into the pump housing, or somehow you have the wrong impeller. Good luck
Attached Thumbnails
Click image for larger version

Name:	17000.jpg
Views:	186
Size:	70.5 KB
ID:	63586  
__________________

__________________
Larry
M/V Pelago
LarryM is offline   Reply With Quote
Old 04-08-2017, 05:13 PM   #3
Guru
 
Bigsfish's Avatar
 
City: Miami River
Country: USA
Vessel Name: Gotcha
Vessel Model: Grand Banks. Heritage. 54
Join Date: Aug 2016
Posts: 2,590
Compare the old impeller with the new one as far as length. Make sure they are the same length.
Bigsfish is offline   Reply With Quote
Old 04-08-2017, 05:19 PM   #4
Veteran Member
 
City: New Bern, NC
Country: US
Vessel Name: Miss Deb
Vessel Model: Nordic Tug 37
Join Date: Sep 2014
Posts: 63
Larry, thanks for the reply and the link.

It is a genuine Sherwood 17000 impeller. I did not remove the cam or the wear plate. Just replaced the impeller after visual inspection of the other parts.

The vanes are only proud of the face by a very small amount, perhaps 1/32", but I suspect even that small amount is too much.

I may try removing it and reinstalling.

Sherwood says do not use a petroleum based grease to lube the impeller, Tony Athens says you can. I always hate it when the manufacturer and a very well respected authority have different recommendations.

Gene
SlowsailNC is offline   Reply With Quote
Old 04-08-2017, 05:37 PM   #5
Guru
 
Lepke's Avatar
 
City: Between Oregon and Alaska
Country: US
Vessel Name: Charlie Harper
Vessel Model: Wheeler Shipyard 83'
Join Date: Jun 2016
Posts: 1,615
For 50+ years I have lubed the shaft and places where the impellers rub with waterproof grease. Compared to what I read here, my impellers last forever. I think it helps with the initial priming so the pump never really runs dry. I don't know how long the grease lasts, because there's no sign of it when I inspect the impellers. Impellers in 2 Detroit Diesel, Perkins 4108 and Onan/Cummings MDL3 are all 5+ years old.
Lepke is offline   Reply With Quote
Old 04-08-2017, 05:59 PM   #6
Guru
 
City: Seaford Va on Poquoson River, VA
Country: United States
Vessel Name: Old Glory
Vessel Model: 1970 Egg Harbor 37 extended salon model
Join Date: Jan 2016
Posts: 2,185
Actually will that cause it to bind, the impellers need to fit close on the sides.
There is a backing plate. Is it corroded or bent or not sitting flat in the pump body?
Take out the cam and backing plate and make sure everything is clean and looks proper.
And is the impeller able to slide down all the way with the backing plate out of the pump, that would tell you the splines are not hanging up the impeller fitting all the way down the shaft.
sdowney717 is offline   Reply With Quote
Old 04-08-2017, 06:22 PM   #7
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 4,946
Is it possible the impeller is in backwards?

Permatex silicon grease works really well. It's thick enough to really stay on rather than just run off.

Another trick I've used to seat the impeller - just today in fact - is a large pair of channel lock pliers. You get one jaw around the back side of the pump body, and the other centered on the impeller hub, being careful not to damage anything. Then a little squeeze will usually push it home.

I hate replacing impellers, and it becomes exponentially more difficult as they get bigger.
__________________
www.MVTanglewood.com
twistedtree is offline   Reply With Quote
Old 04-08-2017, 07:22 PM   #8
Guru
 
City: Seaford Va on Poquoson River, VA
Country: United States
Vessel Name: Old Glory
Vessel Model: 1970 Egg Harbor 37 extended salon model
Join Date: Jan 2016
Posts: 2,185
I would use dish soap, as it is handy.
sdowney717 is offline   Reply With Quote
Old 04-08-2017, 07:41 PM   #9
Veteran Member
 
City: New Bern, NC
Country: US
Vessel Name: Miss Deb
Vessel Model: Nordic Tug 37
Join Date: Sep 2014
Posts: 63
Twisted Tree - not in backwards. One end of the impeller bore is threaded so that you can use a bolt or the Sherwood impeller puller to help remove the impeller. The threaded end is facing the end cover.

But you are right, this is a far more aggravating job than it should be.

It looks like the next step is to remove the new impeller and then verify that the wear plate is seated well. I will also measure the OAL of the impeller. My memory is telling me that there is a post somewhere in the archives where someone had an impeller that did not seat fully, tried another and it did.

Someone else mentioned splines - this shaft/impeller is not splined. The impeller is driven by a key. I used a new key and verified that it fit the shaft and impeller before starting the install of the new impeller.

Thanks to all for spending some of you Saturday replying.

Gene
SlowsailNC is offline   Reply With Quote
Old 04-08-2017, 07:58 PM   #10
Guru
 
Bigsfish's Avatar
 
City: Miami River
Country: USA
Vessel Name: Gotcha
Vessel Model: Grand Banks. Heritage. 54
Join Date: Aug 2016
Posts: 2,590
Just because the package of the new impeller has the proper number on it doesn't make it so. Ask me how I know. Compare the length of the old to new.
Bigsfish is offline   Reply With Quote
Old 04-08-2017, 08:08 PM   #11
Senior Member
 
City: Wherever the boat is
Country: United States
Vessel Name: Silver Quarter
Vessel Model: Bayliner 3870
Join Date: Sep 2016
Posts: 456
Quote:
Originally Posted by Bigsfish View Post
Just because the package of the new impeller has the proper number on it doesn't make it so. Ask me how I know. Compare the length of the old to new.
+1 put some calipers on the old and new. Had conflicting info in my PO's records for my pumps ran into similar (although more obviously wrong).

Also, re grease - petroleum products very unlikely to damage rubber in short term (e.g. minutes hours or even days)
kev_rm is offline   Reply With Quote
Old 04-08-2017, 09:58 PM   #12
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 4,946
The Cummins QSCs that I had on my last boat were tough impellers the change, and they were also sherwood. One thing that happened on mine might be happening on yours too.

Inside the pump body there are openings for the water intake and outflow. When I would install the impeller, I would get it part way in and it would bottom out on something. It turned out that the fins were expanding as they passed by the intake and output openings, then catching on the edge of the far side of the opening. This might be what you are encountering.

To work around it, I had to remove the hose housings from both side and reach in and push the edge of the fins in and over the edge. With that, the impeller would seat fully.

As I recall, mine bottomed out with a lot more than 1/32" sticking out, so you might have a different issue. But it's worth considering.
__________________
www.MVTanglewood.com
twistedtree is offline   Reply With Quote
Old 04-08-2017, 11:19 PM   #13
Guru
 
hmason's Avatar
 
City: Stuart FL
Country: USA
Vessel Name: Magic
Vessel Model: Grand Banks 46 Europa
Join Date: Aug 2013
Posts: 2,246
I have CAT motors with the hateful Sherwood 1700's. Changed the impellers last week. My hands still hurt. I know sbmar makes a replacement pump for Cummins motors with the Sherwood 1700 but I don't know if they make one for CATS.

One trick you can use to seat the impeller is to "bump" the engine but don't let it start and then give the impeller another push. Good luck.
__________________
Howard
Magic, 1996 Grand Banks Europa
Westport, CT and Stuart, FL
hmason is offline   Reply With Quote
Old 04-08-2017, 11:42 PM   #14
Senior Member
 
The Other Gary's Avatar
 
City: Toronto
Country: Canada
Vessel Name: Adios Dinero
Vessel Model: Bayliner 3988 2 x 330 Cummins
Join Date: Sep 2016
Posts: 334
I use a number of electrical wire ties to compress the vanes and liberal amounts of dawn detergent to lube it up. as it goes in I continue to turn it, cutting each wire tie in turn, until almost seated, only then do I install the key. I have never had a problem getting them seated. Don't forget the new O Ring. I use some grease to hold it in place while bolting up. The detergent is also a good check when you fire up again as all the bubbles tell you that it is pumping water.
The Other Gary is offline   Reply With Quote
Old 04-09-2017, 02:36 AM   #15
Guru
 
Irish Rambler's Avatar
 
City: NARBONNE
Country: FRANCE
Vessel Name: 'Snow Mouse.'
Vessel Model: BROOM FLYBRIDGE 42.
Join Date: Apr 2014
Posts: 1,468
Everyone has their own way of tackling this job.
I use Speedseal kits on our boat and washing up liquid as a lubricant.
When I fit impellers I simply squeeze them by hand, use a hammer to LIGHTLY tap it into place, never worry too much if the vanes are not all facing the right way because as soon as you fire up the engine they will pop back into place.
If it sticks as yours appears to have done, the cause can only be one of 2 things, a vane catching on an pump opening and as hmason has already posted, turn the engine but DON'T let it start, either by a flick on the key, OR a large wrench on the front crankshaft nut.
The second reason as Bigsfish has said is that the impeller is not what's stated on the box. Check around the inner rim of the impeller body for the number/type.
Yup ! I once saw a guy in a chandlery shop open a box and exchange the impeller for one he had in his pocket.
Good luck with your wee job.
Irish Rambler is offline   Reply With Quote
Old 04-09-2017, 07:10 AM   #16
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 19,751
IF the pump is hard to reach/see , you might consider replacing all the tiny cover screws with similar SS cap screws.

The hex head can be operated by feel easier than a slotted screw.
FF is offline   Reply With Quote
Old 04-09-2017, 07:58 AM   #17
Senior Member
 
Acheron2010's Avatar
 
City: New Tazewell
Country: United States
Vessel Name: Saoirse
Vessel Model: 1983 Nauticat 44 Ketch
Join Date: Mar 2017
Posts: 151
Go up to the bridge, sit down. Open a very cold beer, sip slowly. Admire the other boats, look for birds, hear the sounds of nature on a peaceful day. Take deep breaths. Now, put calipers on the old and new impeller. If they are the same, install it. If not, go get a different one. And more beer.
Acheron2010 is offline   Reply With Quote
Old 04-09-2017, 12:47 PM   #18
Veteran Member
 
City: New Bern, NC
Country: US
Vessel Name: Miss Deb
Vessel Model: Nordic Tug 37
Join Date: Sep 2014
Posts: 63
Update

The advice to grab a beer and enjoy the scenery is the one that I chose last night. It was time for a break before frustration caused me to do something stupid.

Pulled the new impeller this morning and compared length to the one that came out, exact match. Checked that the wear plate was properly seated and began again.

Used dish soap on pump internals and impeller, wire tires for compression.

Impeller went back in easily and seated deeper into the pump, the vanes were essentially flush with the face of the sealing surface. Removed pump discharge cover and no vanes were caught on the slots. Suction side way too difficult to get to and impossible to see.

A local diesel mechanic happened to be at the marina talking to another owner and I asked him to take a look. He said that it looked good and should not be a problem.

Installed the O-ring, cover, opened the thru hull and started the engine.

While my wife verified water flow I dropped back to the engine room to look for leaks. No leaks, but touched the cover of the water pump and it was really hot. Back up, shut down the engine, scratch head.

Per my wife there was an initial spurt of water then air. So, I am thinking the pump did not prime. Could it be air-locked? Opened the top of the Groco strainer, heard the hiss of air. Secured that back.

Restarted, good water flow, cover cool after ~ 3 minutes of running.

So the next question, could less than 1 minute of dry running have ruined the new impeller? I'm hoping the soap in the pump and on the impeller protected if for that run time. Cautiously optimistic - tell me if you think that is a mistake. Doing this again next weekend would not be fun but it would be better than doing it away from the dock.

Gene
SlowsailNC is offline   Reply With Quote
Old 04-09-2017, 01:20 PM   #19
Senior Member
 
The Other Gary's Avatar
 
City: Toronto
Country: Canada
Vessel Name: Adios Dinero
Vessel Model: Bayliner 3988 2 x 330 Cummins
Join Date: Sep 2016
Posts: 334
The soap saved your impeller. no worries. It is always good to open your seacock just before giving the last few turns on the cover plate. This assures you that all the air is out and the water leaks are stopping as you tighten down and water is immediately available for the pump.
The Other Gary is offline   Reply With Quote
Old 04-09-2017, 02:48 PM   #20
Guru
 
Irish Rambler's Avatar
 
City: NARBONNE
Country: FRANCE
Vessel Name: 'Snow Mouse.'
Vessel Model: BROOM FLYBRIDGE 42.
Join Date: Apr 2014
Posts: 1,468
Unless the water pump is below the water line and as long as the boat is attended there's no need to close the seacock.
The washing up liquid will have protected the impeller.
I use a Speedseal kit which when fitted only has 4 large knurled knobs so no need for screw drivers or spanners and it can run dry for up 20 minutes, once the knobs are unscrewed a little the cover plate swings up and away allowing an easy impeller change.
I would recommend when fitting it to put a spot of Loctite on the screws for peace of mind.
Speedseal details and purchase from Speedseal.com , I've no connection except as a satisfied user.
Now it's my turn for a beer !
__________________

Irish Rambler is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 02:22 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×