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18-07-2015, 20:04
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#1
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Registered User
Join Date: Jul 2009
Location: Ontario, Canada
Boat: Niagara 31
Posts: 252
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Stripped thread in impeller housing. Now What ??!!
The impeller was getting old, so I replaced it. However, although I was being very careful not to use undue force, one of the holes in the impeller housing/dome got stripped as I was attaching the housing/dome back to the engine. The other two bolts are OK. Two solutions:
1) Get new housing/dome.
2) Drill larger hole in impeller housing/dome, tap it and insert larger diameter bolt. (Concerned about strength of hole once more metal is removed - not much to spare on the circumference of the housing/dome now).
Any other suggestions ?
It's a Sherwood G02 pump.
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18-07-2015, 21:24
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#2
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Registered User
Join Date: May 2013
Location: Oregon to Alaska
Boat: Wheeler Shipyard 83' ex USCG
Posts: 3,693
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Re: Stripped thread in impeller housing. Now What ??!!
There are a number of products like helicoil, etc., that replace the bad threads with new ones the original size. They come in kits that include a drill bit, tap and new threads. The advantage is the hole is only opened enough to install the new threads. The insert is like a bushing threaded on the inside and outside. The insert is usually stainless. If put in with locktite, they become permanent.
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18-07-2015, 21:30
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#3
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Moderator and Certifiable Refitter
Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 21,910
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Re: Stripped thread in impeller housing. Now What ??!!
Quote:
Originally Posted by macbeth
The impeller was getting old, so I replaced it. However, although I was being very careful not to use undue force, one of the holes in the impeller housing/dome got stripped as I was attaching the housing/dome back to the engine. The other two bolts are OK. Two solutions:
1) Get new housing/dome.
2) Drill larger hole in impeller housing/dome, tap it and insert larger diameter bolt. (Concerned about strength of hole once more metal is removed - not much to spare on the circumference of the housing/dome now).
Any other suggestions ?
It's a Sherwood G02 pump.
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I'm not familiar with this pump but...
Can you drill two smaller holes either side of the stripped one
or
Can you drill right though and use a longer bolt and loose nut.
or
Can you use metal set in the stripped hole and loosely fit bolt coated in silicone grease. Tighten after metal set has gone off.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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18-07-2015, 21:40
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#4
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Registered User
Join Date: Feb 2013
Location: Oregon
Boat: Seafarer36c
Posts: 5,563
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Re: Stripped thread in impeller housing. Now What ??!!
Do it right, use a Heli-coil. Easy peasy.
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19-07-2015, 05:09
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#5
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Registered User
Join Date: Jul 2009
Location: Ontario, Canada
Boat: Niagara 31
Posts: 252
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Re: Stripped thread in impeller housing. Now What ??!!
I like wotname's suggestions. However what is "metal set" ? If this does not work I"drill right through. Thanks
Sent from my iPhone using Cruisers Sailing Forum
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19-07-2015, 09:42
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#6
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Registered User
Join Date: Jul 2013
Location: home town Wellington, NZ and Savusavu Fiji
Boat: Reinke S10 & Raven 26
Posts: 1,583
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Re: Stripped thread in impeller housing. Now What ??!!
I'd try some thread sealer like Loctite first. Obviously it wont help if there's no thread at all, but if there's a little then might be worth a try. Also use a new bolt, as typically the bolt will have lost some thread too.
__________________
Grant Mc
The cure for everything is salt water: sweat, tears or the sea. Yeah right, I wish.
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19-07-2015, 10:28
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#7
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Registered User
Join Date: Jan 2005
Location: On board
Boat: Van de Stadt 50'
Posts: 1,413
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Re: Stripped thread in impeller housing. Now What ??!!
Drill and tap a new thread for all of them, and if the next size up imperial thread is too big a jump, try a metric size, there might be one in-between.
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19-07-2015, 10:34
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#8
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Registered User
Join Date: Apr 2012
Posts: 353
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Re: Stripped thread in impeller housing. Now What ??!!
If there is enough room, the best fix would be a stud with a nut and washer to hold on the cover.
With a stud it could be as simple as drilling and tapping just a few threads deeper and using devcon 200 or some other metal filled glue to fill around the stud in the old stripped hole.
The beauty of the stud is it does not ever have to be removed from the pump for service.
Take any machining to a machine shop where there are enough tools and knowledge to get a worth-while repair accomplished. Never attempt to drill and tap using a portable drill unless it is an emergency.
By the the way a heli-coil requires a much larger hole than the bolt being replaced. Heli-coils are mostly used to install stronger threads in low strength metals.
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19-07-2015, 11:15
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#9
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Registered User
Join Date: Mar 2011
Location: Darwin Australia
Boat: Jeanneau 45.2
Posts: 45
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Re: Stripped thread in impeller housing. Now What ??!!
Macbeth
I agree with Oleman devcon (or similar ) and a stud have done it on my old yacht . Maybe just a longer stud will screw deeper into the thread .
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19-07-2015, 13:05
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#10
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Registered User
Join Date: Feb 2012
Location: San Diego, CA
Boat: Cheoy Lee 41
Posts: 82
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Re: Stripped thread in impeller housing. Now What ??!!
If there is room a helicoil will restore the original thread if space is available. If not, just try and use the tap for the original size thread to clean out the impeller side and then the die to clean up the screw that goes in, or replace the screw with a new one. Once you do that you may not need to use the helicoil. Next best bet is helicoil. I'd stay away from the loctite idea unless it is an emergency and you need to get underway NOW.
Reference: 10 years navy experience working with electromechanical weapon systems repairs. 5 years working on my own boat and cruising Mexico.
__________________
Invest in experiences, not things.
https://AboardAstraea.com
A growing family's life aboard a Cheoy Lee 41
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19-07-2015, 13:10
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#11
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Registered User
Join Date: Aug 2012
Posts: 811
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Re: Stripped thread in impeller housing. Now What ??!!
Quote:
Originally Posted by macbeth
The impeller was getting old, so I replaced it. However, although I was being very careful not to use undue force, one of the holes in the impeller housing/dome got stripped as I was attaching the housing/dome back to the engine. The other two bolts are OK. Two solutions:
1) Get new housing/dome.
2) Drill larger hole in impeller housing/dome, tap it and insert larger diameter bolt. (Concerned about strength of hole once more metal is removed - not much to spare on the circumference of the housing/dome now).
Any other suggestions ?
It's a Sherwood G02 pump.
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A Helicoil should fix your thread fine. I'm not sure what size you are talking or whether it's a blind hole. A Helicoil does not enlarge the hole very much at all. Only by the depth of a thread. You can do it easily yourself but use a drill press to keep the pilot hole square. Any engineering workshop will do it for not very much as it would only take me 30 minutes to do. Google Helicoil for more info.
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19-07-2015, 15:28
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#12
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Registered User
Join Date: Apr 2015
Location: West Coast FLA
Boat: 1978 Pearson 424 Ketch
Posts: 459
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Re: Stripped thread in impeller housing. Now What ??!!
Hi
are you talking about the cover? when you say domes? if so there is not much stress on it. but drilling it out could make the hole too big even for a helicoil and drilling through wouldn't be good. But you can as suggested above, get some epoxy paste, such as steel putty, any auto parts will have it, clean the hole, leaving what threads there are and insert a small rod made from the epoxy and coat a new screw the same size and thread into the hole, with out the pate. when the epoxy is set, about an hour, back the screw out and install the cover.
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19-07-2015, 15:31
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#13
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Registered User
Join Date: Aug 2010
Location: Longboat Key, FL, USA
Boat: 1988 Hunter Legend 35
Posts: 42
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Re: Stripped thread in impeller housing. Now What ??!!
I did the same on my johnson pump housing which had six screws so I moved to a speed seal cover - something I had planned to do but hadn't gotten around to - which works on four, works out fine!
G
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19-07-2015, 15:56
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#14
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Registered User
Join Date: Apr 2012
Location: Illinois
Boat: Rinker 24
Posts: 399
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Re: Stripped thread in impeller housing. Now What ??!!
Pretty much all of the solutions suggested so far will work.
I looked up a Sherwood "G02" and could only find a G2, does your pump look like this:
If so, I'd be tempted to replace the bolts with studs. The reason being that the housing is easier to install on to 3 studs than it is to hold in place with one hand and then run the bolts in with the other hand, much easier to put the housing on and then it stays there while you can start the nuts, and it is pretty much reversible if you ever change your mind. Use epoxy or locktite, and on the one that is now stripped see if you can either feed a bolt in from the back or epoxy a nut or two onto the back side.
Lastly, the simplest option is if you have this pump pictured is to install the 2 non-stripped bolts and then use another bolt the same diameter but longer and simply back it up with a nut as it looks like you have the clearance in the back.
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19-07-2015, 16:13
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#15
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Moderator and Certifiable Refitter
Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 21,910
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Re: Stripped thread in impeller housing. Now What ??!!
Quote:
Originally Posted by macbeth
I like wotname's suggestions. However what is "metal set" ? If this does not work I"drill right through. Thanks
Sent from my iPhone using Cruisers Sailing Forum
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Metal set = devcon, steel putty, etc.
Helicoils are the proper fix but the others will get you going if you haven't acess to best practice!
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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