Sealing galvanised flexible exhaust

[Jassira]

I have a 5ft length of 2 1/2" flexible galvanised exhaust than runs between the exhaust manifold and the exhaust elbow (Ford Dorset 80hp). It works very well but it isn't 100% gas tight. I've been looking at exhaust wrap but it seems to be mostly aimed at performance engines to improve gas through put and probably wouldn't seal the pipe. Other than that something like Gun Gum exhaust repair bandage would likely do the job but I will need about 10m. Any suggestions ?

 

[anoccasionalyachtsman]

I'd replace it with proper fabric-cored rubber (assuming that it's water cooled). Exhaust bandage dries rigid and would crack and be useless in no time. I've used flexible metal on cars, but would never use it on a boat - precisely because of the leak potential.

 

[lynallbel]

You can get proper clamps that used with a bit of ex paste offer as close as you are going to get a gas tight seal.

2.5" inch 63mm Stainless Steel lap joint Clamp heavy duty exhaust band LP250SS | eBay

 

[pvb]

You can get proper clamps that used with a bit of ex paste offer as close as you are going to get a gas tight seal.

2.5" inch 63mm Stainless Steel lap joint Clamp heavy duty exhaust band LP250SS | eBay

It's the pipe which leaks, not the joints.

 

[lynallbel]

It's the pipe which leaks, not the joints.

In that case its knackered, stainless flex lasts longer, galv siezees then breaks as it tries to flex.

You can get that proper bellow stlye flex with stainless mesh on the outside, weld or clamp on.

 

[Jassira]

That section of the exhaust is dry so rubber exhaust hose isn't an option. The pipe is new and the lack of air tightness is a feature of the pipe, it's normal usage is things such as generators which I guess don't run in enclosed spaces.
Flexible Exhaust Pipe - Flexiducting & Tubing Ltd
The leakage is very slight, you can smell it when the engine has been running hard and soapy water brushed onto it will show bubbles, it could probably be controlled by an engine room extractor fan, but that seems a bit like putting a bucket under a leaky roof. If I have to replace the whole lot with something different then so be it, but a wrap that will seal it would be ideal.

 

[jwfrary]

You need some proper marine type pipe which is heavier than the stuff your using.

or go with solid pipe with flexible joints at each end. Look at Tony’s tips on sbmar.com for a good article on dry exhausts

 

[Bodach na mara]

You can't get away with this sort of stuff on a boat. You mentioned that the normal use of this pipe is on generators and such,which operate in open areas. Also GunGum may be fine on the exhaust under a car but should not be used in the boat exhaust. As others have said, replacement is your only safe option.