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Old 31-10-2012, 18:44   #1
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Cracked Exhaust Elbow - Looking for Jerry Rig Help

I was just inspecting our engine and noticed that the exhaust elbow is cracked on one side.

The crack is in the middle of the elbow, extending down about half of it. I turned the engine on and watched it for awhile to see how badly it was leaking, but after 10 minutes there was no visible dripping or exiting exhaust.

We're currently in Vanuatu, getting ready to head to Australia, and I think it's going to be better for us to deal with it there than here. We don't use the engine for power, so we have very little motoring required before we can replace the elbow. However, we do have to motor about 7 miles up a river when we arrive in Bundaberg.

So, I'm wondering if people can think of anything I can do to minimize the chance of the elbow failing in the next 1 to 3 hours of motoring. I've preemptively wrapped it in Rescue Tape (for whatever that's worth), and can't really think of anything to do except drink kava and prey.

How long can cracked elbows last before full failure?
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Old 31-10-2012, 18:53   #2
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JB Weld works well in this situation.
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Old 31-10-2012, 19:06   #3
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

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Originally Posted by kb79 View Post
I was just inspecting our engine and noticed that the exhaust elbow is cracked on one side.

The crack is in the middle of the elbow, extending down about half of it. I turned the engine on and watched it for awhile to see how badly it was leaking, but after 10 minutes there was no visible dripping or exiting exhaust.

We're currently in Vanuatu, getting ready to head to Australia, and I think it's going to be better for us to deal with it there than here. We don't use the engine for power, so we have very little motoring required before we can replace the elbow. However, we do have to motor about 7 miles up a river when we arrive in Bundaberg.

So, I'm wondering if people can think of anything I can do to minimize the chance of the elbow failing in the next 1 to 3 hours of motoring. I've preemptively wrapped it in Rescue Tape (for whatever that's worth), and can't really think of anything to do except drink kava and prey.

How long can cracked elbows last before full failure?
Had a cracked exhaust elbow happen in the middle of a cruise. Used some metal bug screening wrapped around the elbow saturated with Marine Tex Grey. Repair lasted over a year.
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Old 31-10-2012, 19:19   #4
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

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JB Weld works well in this situation.
Definitely my choice to try would be JB Weld or other similar high temp epoxy like Marine Tex or whatever is available in Vanuatu.
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Old 31-10-2012, 19:26   #5
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

Cracked exhaust manifold first week I owned the boat, 15yrs and 12,000 hours later I sold the boat with JB Weld patch still intact.
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Old 31-10-2012, 19:42   #6
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

I agree with the JB Weld or MarineTex plan and I would also press it with the tension of a couple of large stainless hose clamps around the elbow if you can manage a fit.
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Old 31-10-2012, 20:11   #7
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

I solved a similar problem with JB Weld. Cleanliness is key and I would also recommend sanding the crack and surrounding area with 80 grit and cleaning again.
I JB Welded the hole, wrapped it really tight with 2 layers of 1 strand of copper wire and another layer of JB Weld over the top. It lasted 12 years on a racecar oil cooler.
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Old 31-10-2012, 21:09   #8
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

Can you get a drill in there?

If so, I would drill a small hole at each end of the crack. This is standard procedure to stop a crack from growing, as the stress hits the hole it distributes around it instead of tearing further into the metal. If you can do that--the rest is more of patching and less of structural questions.

Either way, I would wire brush or sand the metal, because epoxy bonds best to clean metal. Then I'd spread some epoxy (JBWeld certainly is one good one) allthe way around the elbow, and maybe 3/4" to 1" either side of the crack.

Now, think about why your hull is not epoxy or another resin--it is fiber reinforced. Before the epoxy can set up, neatly wrap the elbow with baling wire or seizing wire or the strongest string you have, so it coils in and absorbs the epoxy. Add a little more epoxy over it. If you have no string or wire, try a bandage roll or screening.

The idea is, you've stopped the crack from propagating, AND added strength to the patch, to further reinforce it. Is that overkill? Perhaps. But a really good kludge can last a really long time. I'd rather overdo it, than have the patch crack off.
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Old 01-11-2012, 00:09   #9
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

G'Day kb,

First, the patching advice above will likely last a good long time.

Second, the customs wharf is only about a mile up the Burnett from the entrance, and most folks stay a while there at the Bundy Port Marina. Under many wx conditions it is easy to sail up the river that far, for it is reasonably wide. If you should arrive during the flood tide it becomes even easier. And there are repair facilities there at the marina, including a welder, so you should be able to effect a more permanent repair or order a new part.

So, you can turn down the gain on the worry meter a notch!

Cheers,
Jim
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Old 01-11-2012, 02:22   #10
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

If its a horizontal crack what about a couple of hose clamps.
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Old 01-11-2012, 03:40   #11
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

Quote:
Originally Posted by kb79 View Post
I was just inspecting our engine and noticed that the exhaust elbow is cracked on one side.

The crack is in the middle of the elbow, extending down about half of it. I turned the engine on and watched it for awhile to see how badly it was leaking, but after 10 minutes there was no visible dripping or exiting exhaust.

We're currently in Vanuatu, getting ready to head to Australia, and I think it's going to be better for us to deal with it there than here. We don't use the engine for power, so we have very little motoring required before we can replace the elbow. However, we do have to motor about 7 miles up a river when we arrive in Bundaberg.

So, I'm wondering if people can think of anything I can do to minimize the chance of the elbow failing in the next 1 to 3 hours of motoring. I've preemptively wrapped it in Rescue Tape (for whatever that's worth), and can't really think of anything to do except drink kava and prey.

How long can cracked elbows last before full failure?
I have experienced this before while circumnavigating and repaired the elbow by TIG welding in Thailand.

You did not include engine model...But, if you have JB Weld, as suggested, it could be a semi-permanent patch. However, if you do not have it, it is going to be hard to find...I had a hard time finding it in NZ.

Cracks on elbows normally occur near a weld in the elbow and they start with a series of very tiny pin holes. Normally, when they start, you will not see seepage, but will notice salt deposits near the weld/hole/crack. Eventually, you should replace the elbow, but I have TIG welded one before.

I suspect that you will have hundreds or hours before a large quantity of water leaks through the fault...but, neither you or I have any idea how long this has been going on. Also, I doubt that the elbow would break in half, but if it did, use the emergency tape again and be sure that your bilge pump is ON and that you keep areas well ventilated while the engine is running.

FYI, I kept the repaired elbow as a spare. I have a spare for the main engine and the generator, but we are circumnavigating.

Hope this helps.

Bill
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Old 01-11-2012, 13:43   #12
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

Thanks, all. I'd forgotten how great a resource CF can be. These suggestions are great - I'll try the Marine Tex, bailing wire, hose clamp route. Makes sense and seems easy enough.

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Old 01-11-2012, 15:25   #13
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Have one fabricated
A lot of the water elbows were sold as optional equipment and can be quite expensive. Some sold by the engine manufacturer are NLA no longer available. They are easy to fabricate. In many cases they are an upgrade to what you had because they breath easier than many of the OEM versions. They are also less prone to carbon up. Use schedule 80 black pipe & fittings. they can be found at commercial plumping supply or someplace that does boiler work or installs fire sprinkler systems. You will not find schedule 80 at Home Depot they will have no clue what you are talking about if you ask. Do not use S/S, galvanized pipe or schedule 40 black pipe. S/S pipe gets brittle from heat it will break from engine vibration, schedule 40 black pipe is to thin It will rust through. Galvanized pipe will rust through.

Send me a PM or call me if you need additional help... Good Luck with your project.
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Old 01-11-2012, 15:43   #14
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

When ours cracked (cast iron, very, very bad crack) we wrapped it in a fine metal plate then covered with glass cloth and resin (about half an inch thick).

It worked fine for another year or so.

So I think a plate/glass/resin solution may sometimes be employed for in situ repairs.

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Old 01-11-2012, 15:43   #15
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Re: Cracked Exhaust Elbow - Looking for Jerry Rig Help

If it's in the wter jacket only the worst you'll get is water in the bilge. If it's not leaking at all... are you sure it's not just a casting line?
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