Author Topic: Removing thru-hulls  (Read 1629 times)

svsurprise

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Removing thru-hulls
« on: July 11, 2016, 08:51:33 PM »
Does anyone have a creative way of removing old 2" thru-hulls?  I have a few in my 44 w/o with rotten backing blocks.  I think the two on the port side of the engine (intake and drain) are going to be especially tough given the poor access.  I am considering using a sawzall to cut through the block, bolts and threaded thru-hull to avoid having to unscrew the valve from the thru-hull.  I am not 100% certain but I don't recall seeing any flanges on the thru-hull itself which would facilitate using a thru-hull wrench.  Previous experience with a smaller thru-hull revealed that CSY were bedded their thru-hulls in with some pretty tough stuff sealant and I ended up grinding the thru-hull down to pop it out  I hope to salvage the valves and just replace the thru-hulls themselves.   

Any advice is appreciated.
Don

Steven Rice

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Re: Removing thru-hulls
« Reply #1 on: July 12, 2016, 12:09:02 AM »
If you can get the seacock off the thru-hull, you should be able to chip the backing board away which will remove the 3M 5200 sealant that CSY bedded with originally. use the special 5200 sealant remover solvent if you can find it by dripping it in the joint between the thru hull and the hull. If not, cut and gouge as much of the sealant out as you can from inside the hull.
Then, from outside, using a propane torch or equivalent, slowly heat the thru hull till it is hot to the touch, but not hot enough to damage the surrounding glass. use a scraper or other thin steel wedge driven with a hammer between the thru  hull flange and the hull a little at a time around the flange. then find a tool or piece of flat steel that will fit snuggly in the bore of the thru hull. They came with 2 ridges in the bore for the purpose.  Use a wrench to turn the tool and rotate the thru-hull out. It may take some re-heating to accomplish.
I replaced most of my thru-hulls using this method on my 44".

svsurprise

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Re: Removing thru-hulls
« Reply #2 on: July 14, 2016, 07:37:04 AM »
Thank you for the helpful advice which I will certainly try.  My concern is mostly about your first sentence "If you can get the seacock off the thru-hull".  That's my worry but I won't know until I tackle it this fall.  In any case, thanks again. 

Mike Zofchak

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Re: Removing thru-hulls
« Reply #3 on: July 14, 2016, 10:47:44 AM »
I just removed all thru hulls in my engine room. Believe it or not they came out fairly easy. Here is the process I used.

1.   Buy a radiator spud wrench. ( Found one at a HVAC/Plumbing wholesale for about $9.00)
2.   Heat the mushroom head with a propane torch. I did not get it super hot.
3.   Insert the spud wrench to the appropriate size and simply backed them out with a 14” pipe wrench attached to the spud wrench. The valve was held in place with the bolts thru the hull.
4.   Went inside and removed the nuts from the bronze bolts thru the hull. Bolts actually broke.
5.   Removed valve. Cut old bolts flush with old backing wood (My backing wood is in great shape so I did not have to remove it).
6.   Interesting fact about the bolts. They were originally carriage bolts but the head of the bolt has disappeared. The plan is to grind them just below the surface and epoxy/ seal over them and then drill and install new hold down bolts.
7.   Had a friend blast the outside of the valves. The next step is to service them and reinstall after engine room work is completed. Still on the fence what to bed them with. ANY suggestions would be appreciated.

Check out www.compassmarine.com as he has a great article on thru hull installation and servicing them as well.

Good luck with the project and feel free to contact me with any questions.   
Capt. Mike Zofchak
Land Locked S/V Buckeye Queen

svsurprise

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Re: Removing thru-hulls
« Reply #4 on: September 27, 2016, 07:23:04 AM »
Mike, Thanks for the suggested method of removing old thru hulls.  I used your method yesterday in the engine intake and aft head discharge thru hulls and it worked like a charm.  The boatyard lent me a thru hull wrench and long pipe wrench which made it a bit easier.  The only suggestion the manager had was to place some wet towels around the seacock in case of any flare ups and to cool the fiberglass in case of overheating.  About a minute or two with the torch loosened up the bedding enough to allow the threaded thru hull to easily be removed.  The hard part for me was removing the old rotten backing blocks. 

It's all prepared for replacement now.  I'll be using 3/8" fiberglass backing blocks and sikaflex polyurethane sealant. 

Thanks again, Don

Peter Roach

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Re: Removing thru-hulls
« Reply #5 on: February 07, 2017, 09:58:20 PM »
Heat it up with a torch and then step on it from the inside. Make sure your boots are thick. They will come out easy.
I tried having a bad day once but I did not like it