Bonding stainless to aluminium

[Durcott]

Hi Folks,

I have an outboard that runs in a locker well. (Not this guy AGAIN...)

The exhaust fumes from the leg outlet are collected by a stainless steel 'manifold' and vented. When the manifold is gas tight, the motor runs well. When it isn't, it doesn't.

The leg is old, and the ally is in poor condition. No amount of re-rivetting is keeping the joint gas tight. I have attempted a proper fix with a combination of rivets, sikoflex and that emergency underwater epoxy repair putty.

That attempt was the best so far, but there is still no real bonding there, and it failed after half a season.

There's not enough metal left to redrill for larger rivets, but there is a reasonably large flange on two sides of the manifold. Does anyone have a solution for bonding this item directly to the outboard leg?

I may have to abandon good taste and just bandage the thing in place.

Cheers

Jeff

 

[monkfish24]

Do you have a picture of the arrangment?

Could some exhaust repair bandage work, the kind of stuff that is applied wet and it dries solid help?

 

[lw395]

Epoxy will stick fairly well to aluminium.
Maybe epoxy on a thicker bit of ali and screw the stainless to that, using a sealant of some sort.
Is it possible to take the strain off the glue etc with say, big hoseclips around the leg?

 

[CreakyDecks]

What happens if you block the leg outlet completely?

 

[Durcott]

I wondered about that. What is this exhaust port actually for? Well, I guess there is not enough pressure at idle to force the exhaust through the prop, but other than that, I'm not sure why not. All the problems with this arrangement are at idle as it happens, as the engine tries to breath its own exhaust.

Jeff

 

[Durcott]

Oooh - that's a cracking idea. So - I remember using a 'loaded' epoxy on a heat exchanger, and that bonded well.

That certainly feels like a solution, and not a bodge. Large hoseclips was going to be next on my list. Hate to think how much they'd be for that size though ;-)

Jeff

 

[davidej]

J & B Weld is an epoxy designed for metal to metal bonding.

I find it works very well but will not survive full exhaust temperature - no epoxy will.

 

[Durcott]

My crude experiments at the moment suggest that by the time the exhaust has got this far, it's lost its heat to the leg, and the leg is cooled by immersion.

Long term - who knows. Maybe this is the fundamental problem, but it usually feels cool.

Jeff