Replacing exhaust

[Strettonman]

Hi, 

 

we’re new to boating having just bought a fairly cheep narrow boat that was well looked after but dated and hadn’t run for a couple of years. After a couple of days boating the exhaust (15” cylindrical silencer box) gave up so I’ve taken a look and it looks quite easy to replace as long as I can free up the two cylindrical nuts connecting the silencer to what looks like a flexible coupling to the engine and the one to the pipe out the side of the boat. 

 

So  I have a couple of questions before I decide whether to tackle it or get a pro to change it. 

 

1) how do I free up the threads ? They look pretty rusty so should I use WD40 or is that not appropriate on an exhaust or is there something better ? 

2 ) do I just need to use brute force with a set of good pipe grips or is there a knack to the loosening the cylinder nuts ? Do I need to do anything with the flexible coupling ?

3) do I need to use and sealing compounds as you would with water pipe. 

 

I always leave it to the pros with car exhausts as it’s generally cheaper anyway but I guess that isn’t the case with boats. 

[ditchcrawler]

Plus Gas penetrates much better than wd40 then big stilsons, If you can get it all off the boat its easier.

[bizzard]

And keep tapping fairly hard either side of that threaded collar with two hammers in unison. This will spread it slightly and shake up and help to free the rusty threads.

[Strettonman]

Ditchcrawler and bizzard. 

 

Thanks for the tips. 

[bizzard]

6 minutes ago, Strettonman said:

Ditchcrawler and bizzard. 

 

Thanks for the tips. 

If you have access to a blow torch,preferably oxy-acetylene play the flame horazontally back anf forth along just ONE side of that threaded collar. You want to expand the collar only with heat and not the  whole pipes going into it if possible.  Stilsons are best for gripping on those collars.

Edited January 13, 2019 by bizzard

[mark99]

Plus Gas as DC said is MUCH better.

 

I had same issue.

 

Loads PLUS GAS left for overnight - undid ok. (Hard to buy this stuff off the shelf these days for some reason)

 

Total fail with WD40.

Edited January 14, 2019 by mark99

[Stilllearning]

As has been said above, with a couple of additional suggestions. Remember that the silencer box is scrap, so break it up in situ and get rid of it before the rest of the job, as it is in the way. Use a large Stilson on the coupling, and another one on the pipe, to hold the pipework in place. This will make you able to put even more effort into making the coupling move.

[Tony Brooks]

1 minute ago, Stilllearning said:

As has been said above, with a couple of additional suggestions. Remember that the silencer box is scrap, so break it up in situ and get rid of it before the rest of the job, as it is in the way. Use a large Stilson on the coupling, and another one on the pipe, to hold the pipework in place. This will make you able to put even more effort into making the coupling move.

And it helps prevent the flexible pipe unwinding itself and breaking. Be prepared to fit a new flexible as well, you may need to.

[Strettonman]

Thanks everyone for the advice. 

 

I’m quite Looking forward to the battle ahead ?. 

[Mad Harold]

3 hours ago, mark99 said:

Plus Gas as DC said is MUCH better.

 

I had same issue.

 

Loads PLUS GAS left for overnight - undid ok. (Hard to buy this stuff off the shelf these days for some reason)

 

Total fail with WD40.

Got a tin of Plus Gas  recently from Halfords.

[aracer]

The "plus gas" I bought off the shelf (that is dependent on having a local Screwfix, but I seem to be surrounded by them now)

https://www.screwfix.com/p/no-nonsense-penetrating-lubricating-oil-750ml

[WotEver]

8 minutes ago, aracer said:

The "plus gas" I bought off the shelf (that is dependent on having a local Screwfix, but I seem to be surrounded by them now)

https://www.screwfix.com/p/no-nonsense-penetrating-lubricating-oil-750ml

That link appears to be broken but the reviews all refer to it as a “WD40 replacement”. 

https://www.screwfix.com/p/no-nonsense-penetrating-lubricating-oil-750ml/19320?_requestid=595229