Exhaust thru hull elbow problem

[solmaniac]

I've been fighting this thing for two days so far. Started the job of replacing exhaust elbows and hoses since one the iron ones that have been in place since there were dinosaurs finally corroded enough so nothing left for the hose to hold to.
There is a 3" elbow at the thru hull that I cannot get off that is threaded on. I am thinking there must be a better way to go about it...or maybe I'm going all wrong. I have been trying to turn the elbow counter clockwise off the threads coming out of the thru hull I have managed to move it about a 1/4 turn using various tools such as chain wrench, pipe wrench, breaker bar, hammer, PBlaster. I now see that what has moved is not the elbow off the threads...but the threads in the thru hull. I'm thinking I must be turning the whole thru hull? Or, tightening it more? It looks like there is a locknut on these threads...but I'm really not sure how this thing goes together.
Any help is appreciated. The boat is a Westsail42. I am including a picture inside and out.
exhaust elbow.jpg Views: 186 Size: 384.7 KB ID: 121514" style="margin: 2px" />

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[Cheechako]

I cant see much detail, but if you are turning the thru hull then you need someone outside with a thru hull wrench to hold it. That appears to be a pipe thread elbow (?) If so it is on the threaded mushroom which has straight threads inside the elbow tapered threads. so they probably put it on real tight as it only has a couple threads holding it likely. If you are doing the same thing then you may have to cut it off.. hard to say. it appears the mushroom's threads may be long enough to cut the elbow off and reuse the shorter mushroom... Although I would likely replace it.

[Afrakes]

The thru hull is definitely turning. Ditto having someone with the proper wrench holding the thru hull while you try to remove the elbow. Some judiciously applied heat may be necessary.

[Badsanta]

If your replacing this, I would just hacksaw this and cut the elbow off then put the blade into the Thru hull hole and saw the nut to split it.

[roberthowell]

give in and replace both

[s/v Jedi]

Cut everything off and start with a new bronze thruhull fitting and a flanged adapter on the inside. Both available from Groco. This gives you a male threaded end on the inside to work with, plus a setup where the thruhull fitting will never turn again like this one does.

[a64pilot]

I was thinking Sawsall myself,

[Badsanta]

That flange adapter rocks. Best thing made for that.

[deblen]

4-5" disk grinder with cutting disk. Cheap one $30. Last a lifetime for occasional use & you will use it a lot.
Cut the elbow just above the bronze & then cut two vertical slits in the remaining "ring"
Replace thru hull with the flanged adapter bolt thru style as mentioned by prev. poster.
http://www.groco.net/seacocks.htm

http://www.pbase.com/mainecruising/replacing_thruhulls

[RaymondR]

Unscrew the nut on the thru hull as much as you can then push it out so that the head of the thru hull clears away from the hull and cut the head off it with a disk grinder then pull the elbow and sawn stub into the boat.

[keepondancin]

Had a similar situation. I would follow RaymondR's suggestion. If you can't loosen the nut, go to the outside and grind off the flange and push the through hull into the boat. It may take a large pipe wrench to turn the remains of the through hull to break the adhesive sealant.

[solmaniac]

Thanks for advice everyone. I ended up cutting the elbow off flush with the thru hull threads. The thru hull looks pretty good really...just lesser amount of thread now. There is still 1-1/4 inch of thread remaining. I have a good quality rubber elbow that I think I can clamp on the remaining thread. Certainly enough room for 1 high quality 3/4 inch clamp. Not quite enough for two.

[mike d.]

You need a thread to hose adapter on the thru hull. If you just clamp the rubber elbow on, with sealant it will eventually leak! Also you have broken the seal to the hull, so you still need to remove the thru hull, clean rebed, reinstall.

[s/v Jedi]

Originally Posted by solmaniac

Thanks for advice everyone. I ended up cutting the elbow off flush with the thru hull threads. The thru hull looks pretty good really...just lesser amount of thread now. There is still 1-1/4 inch of thread remaining. I have a good quality rubber elbow that I think I can clamp on the remaining thread. Certainly enough room for 1 high quality 3/4 inch clamp. Not quite enough for two.

You're cheaping out on a crucial part of the boat. I recommend you do it right and save money elsewhere

[solmaniac]

Okay...points taken. I'm going to have to look at this as a temporary solution because I have to move the boat soon.

So far haven't been able to locate 3" female thread hose adapter. Hose in the existing system was clamped directly onto threads protruding from elbows. The hose didn't leak until the threads rotted away. I'm guessing after 40 years.