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Fake Rivets!


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This is the water cooled silencer of a Kromhout M1:




The owner has had a bit of an epic saga with this silencer due to it being cracked and leaking:




There have been previous attempts to fix the cracks by welding:




As you can see, this hasn't been successful. Not an easy weld to make of course. The top and bottom of the silencer have closing plates:




So, it's unlikely that the silencer was going to fall apart. It has an internal 'pipe' and fins to connect the inner and outer together, so again it is unlikely to drop to pieces. That just leaves the leaks.


As a pragmatic solution, the owner got some steel plate rolled, which I cut into parts:






Next up was drilling and tapping lots of little holes and fitting cap screws:






Hopefully, that will stop the leaks. The correct permanent solution is of course to weld it. If somweone wanted to do that in the future, the bolted plates are a reversible solution


I also think it has a suitably period look to it as though it is an old repair. It will look a lot better under a coat of paint




Oh yes, fake rivets:



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Reminds me of a repair I did to my Mini sump, many moons ago, after smashing a hole in it on a monster mooring ring. Heavy Ali sheet, wrapped around the base & front to cover the hole, & secured with loads of closely spaced drilled & tapped machine screws & bedded on silicone. Worked a treat, lasted for years (until the car eventually died for other reasons).


I also did a similar repair on a frost-cracked large watercooled exhaust manifold (Crossley 2-stroke), but ground out the crack, filled it with Belzona and bedded a cover plate in Belzona. It's still holding maybe 10 years later with the engine in regular-ish use. The steel cover plate is starting to rust a bit, though, stainless might have been better - though the Belzona might not have bonded so well to that?



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Any idea why the exhaust was water jacketed Tim?




To cool it (the gases) as well as reducing heat radiated to engine room, I think. Normal practice for many marine engines.

Probably also reduces noise in engine room.



Edited by Timleech
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an ideal part to get gas welded in a furnace, the best way to repair such things iv'e heard.


It is indeed. You would need a pretty big furnace, mind. It's the best part of three foot long


Chewing gum by the looks of it. That lot must have taken some chewing!

What boat Richard? Firefly?





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The silencers on marine engines are water jacketed to reduce the risk of fire. Simple as that. A silencer without a jacket would not have got Lloyd's approval for use on board ship.


I know this engine well. I imported it from Holland. Part of the problem is that the installation of the plumbing in the cooling system encourages a lot of pressure. This should not be the case and is a fault of the fitters not the engine!


The easiest way to repair this would be to braze it. If done buy a skilled individual it can look brilliant and does not rely as much on the integrity of the original material as welding. I had a brazed frost repair on the side of the exhaust box on my Petter S that looked wonderful.



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No I don't. I have seen them come up for sale in holland before though. I think some enquiries through some of the museums/associations there would turn one up pretty quickly.


There are quote a few M1 engines for sale. A call to the seller might find that a spare sprayer body and nozzle might be available as a separate transaction.


Just a case of looking around. I know a firm in Germany that specialises in the refurb of hot bulb jets.



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