exhaust question

[hillyarder]

Since i launched tyhe boat I had been plagued with a too hot engine, water just dribbling out the exhaust and lots of 'soot' in the water. I thought it was the impellor but that was ok. i read on the forum that soot in the water was back pressure. i decided to look at the exhaust which is inch and half bsp threaeded pipe going onto a rubber pipe. i suppose i should have realised it was the exhaust as it was 40 years old. i took off the asbestos wrapping ! and most of the exhaust just fell to bits. the bit that didnt was almost completely blocked. i cannot believe the engine run at all but it did and quite well. i had a new pipe made up (cost 30 quid - the rubber pipe was twice as expensive). now the question is should i fit a muffler in the rubber pipe as the exhaust has no silencer. will a muffler cause any backpressure problems. the engine runs like a dream now. its a petter 12hp twin by the way. i have been told i need a water trap but the loop in the steel exhaust is way above the water line and it has been ok for 40 yrs. also is there a modern alternative to the asbestos wrapping which migfht leave the metal cooler to the touch.
sorry for going on a bit. thanks for any help.

 

[mtb]

why change what works well,you can get tape which is similar to fire blanket material.
AS long as you have the loop above the water line why worry , just be sure you can drain it down for winter.
Cheers
Mick

http://homepage.ntlworld.com/boats
I want a big steel ex trawler or tug v, cheap or swap for tug

 

[philip_stevens]

To a certain extent, the water trap will also act as a muffler. I had a straight-through exhaust on my Bukh that made a lot of noise (obviously), so fitted a water trap. It made a hell of a difference to lessen the noise.

regards,
Philip

 

[Avocet]

I have a Vetus plastic watertrap and a Vetus plastic muffler on a BMW D12 (12bhp). It's exhaust is very quiet (pity about the mechanical noise!) and it doesn't seem to have discernably less power than before I fitted either.

Hope this helps.

 

[clyst]

Hi All
Picking up on the point of Hillyarders query regarding an alternative for asbestos insulation I too am interested in an alternative . Anybody know of a trade name or a supplier ?

Fair winds to you all!

TERRY

 

[alanporter]

The alternative for asbestos is a fibreglass bandage. You should be able to get this at any marine engine dealer, or perhaps cheaper, an automotive supply house. I have been using it for years, and it is just as effective as asbestos. I can't give you a brand name because I am in western Canada and brands are different over here. Good luck.

Alan Porter

 

[Strathglass]

You can get it from ASAP, http://www.asap-supplies.com/ in various widths/thicknesses. It is relatively inexpensive.
Iain

 

[dickh]

I had a similar problem with a blocked exhaust; one point though, did the water flow increase and your 'too hot' engine problems improve when you replaced the exhaust pipe? If you now get a reasonable flow, seriously consider a Vetus water trap or similar - you will get a much quieter exhaust, but there must be a good flow of water to keep it cool as it is made of plastic.
As long as the engine starts easily you won't have a problem; which can arise if the engine takes a long while to fire up and the water trap can fill up with water and back up to the engine.


dickh
I'd rather be sailing...