JB Weld

With sea water one side trying to get in and hot oil the other side trying to escape I would not be wanting to use a 2 part epoxy.
Why is it cracked? Could it get bigger? What size is the engine ?


limecc said:
I would trust a Durafix repair though
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That's just as crazy on a brake lever. There is always the risk of weld failure at the critical time of an emergency stop.
Just buy a new one, it's not like they are expensive.
 
Rappey said:
With sea water one side trying to get in and hot oil the other side trying to escape I would not be wanting to use a 2 part epoxy.
Why is it cracked? Could it get bigger? What size is the engine ?



That's just as crazy on a brake lever. There is always the risk of weld failure at the critical time of an emergency stop.
Just buy a new one, it's not like they are expensive.
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How hot do you think that oil is with it in the water all the time.

Dont know why it is cracked

60hp

How would you deal with it
 
Bigplumbs said:
The crack is very small and I don't even know yet if it goes all the way through. When it is not raining so much I will investigate further.... No real hurry on this one.
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Does it leak? Is there evidence of water ingress/emulsification of the gear oil? If there isn't then ignoring it might be a reasonable course of action.

limecc said:
Speaking as a qualified former engineer, have to fundamentally disagree with your statement. Durafix is actually stronger than the base alloy. Belzona, JB weld or whatever, there's no comparison. Durafix is blend of metals, not a resin. It will never separate or crack and it's a harsh environment which caused the crack in the first place.
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We don't know what caused the crack, making assumptions isn't helping the OP reach a satisfactory outcome.
 
penfold said:
Does it leak? Is there evidence of water ingress/emulsification of the gear oil? If there isn't then ignoring it might be a reasonable course of action.

We don't know what caused the crack, making assumptions isn't helping the OP reach a satisfactory outcome.
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Will check the gear oil when the weather is being kinder. Thanks
 
Bigplumbs said:
How would you deal with it
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Would get it welded or use the aluminium alloy rods and a blow torch. Once done you would not have to worry about it again.

Could we see a pic ?

If say tig welded would the cold gear oil take away localised heat from the critical parts ?
 
Rappey said:
Would get it welded or use the aluminium alloy rods and a blow torch. Once done you would not have to worry about it again.

Could we see a pic ?

If say tig welded would the cold gear oil take away localised heat from the critical parts ?
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Have you ever tried using the aluminium rods. I have and so has a very skilled friend of mine. It does not work. If you try, and get it to work even on a simple test piece with no contamination and small so the heat is not taken away let me know
 
Rappey said:
If say tig welded would the cold gear oil take away localised heat from the critical parts ?
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Yes it would and the rest of the gear casing and leg would also be a massive heat sink. That is why limecc said to put it in the oven. imagine having a 60 hp outboard leg in your oven next to the Christmas turkey :)
 
I will post a pic but it is a very small crack that is why I like the idea of the patch.

Another thought I had was some self amalging tape
 
Bigplumbs said:
Yes it would and the rest of the gear casing and leg would also be a massive heat sink. That is why limecc said to put it in the oven. imagine having a 60 hp outboard leg in your oven next to the Christmas turkey :)
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You'd have to have stripped and de-greased the casting otherwise the turkey would taste off
 
Bigplumbs said:
Have you ever tried using the aluminium rods. I have and so has a very skilled friend of mine. It does not work. If you try, and get it to work even on a simple test piece with no contamination and small so the heat is not taken away let me know
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Durafix rods don't need much skill, the parent metal remains well below melting point. It's not really welding, soldering or brazing better describes it.

I wonder if you can get some penetrant dye and developer to see how bad the crack is? Perhaps ebay I didn't check.

You spray on the thin red dye, wait 5 mins then clean it with solvent spray. Then you spray the chalky white developer which draws out trapped dye and tells you the extent of any crack. Afterward you wipe it all off with a dry cloth.
 
It's possible that isn't into the oil side, O/Bs with exhaust exiting through the hub have the seals etc quite a long distance forward into the casing. There appears to be pitting near the open end of the crack, perhaps a combination of heavy handling(removing the end casting when working on the gears etc can be difficult due to corrosion and the temptation to reach for the biggest hammer is great) and corrosion has created the crack. I'd say that is not fixable by welding or durafix without stripping, as the heat will attack the O-rings.
Rappey said:
If say tig welded would the cold gear oil take away localised heat from the critical parts ?
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If the crack is into the gear case oil reservoir that would be a bad idea; the oil will be present in the crack and even in very small quantities would contaminate the weld; welding diecast aluminium is difficult enough without adding that. I'd be surprised if the OP could get any welder to attempt it without the casing stripped and thoroughly cleaned, certainly not with any guarantee of success anyway.
 
Bigplumbs said:
Have you ever tried using the aluminium rods.
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I have. They came with good instructions. Firstly a good blowtorch is needed as I found the ones with an aerosol type gas cylinder do not get hot enough.
Repeated brushing of the aluminium with a stainless brush also seems critical to achieve any weld. Granted its not always easy and I would not use it on something that needs strength.
I would guess that there will be a fair amount of loading in that area of the crack and maybe the crack is due to that.
I would drop the gearbox making it more portable, remove that bolt on ring and asses from there.
After watching a few vids I fully understand your reluctance to strip the gearbox.
I did grab a screenshot that may help (yamaha 60) . Seems its exhaust channel on the other side ? Might be an idea to look inside to see how far the crack goes. Screenshot_20221125-104052_YouTube.jpg
 
Rappey said:
I have. They came with good instructions. Firstly a good blowtorch is needed as I found the ones with an aerosol type gas cylinder do not get hot enough.
Repeated brushing of the aluminium with a stainless brush also seems critical to achieve any weld. Granted its not always easy and I would not use it on something that needs strength.
I would guess that there will be a fair amount of loading in that area of the crack and maybe the crack is due to that.
I would drop the gearbox making it more portable, remove that bolt on ring and asses from there.
After watching a few vids I fully understand your reluctance to strip the gearbox.
I did grab a screenshot that may help (yamaha 60) . Seems its exhaust channel on the other side ? Might be an idea to look inside to see how far the crack goes. View attachment 146711
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Very interesting. Lets hope the exhaust area is a way back as you say.

This is only a Spares or repair Engine I bought of ebay and I have the exact same engine on my Rib so if I cant fix it it will be a nice lot of spares. When the weather improves and I get a nice clear morning I will have another go.
 
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