Silencers & Bilge Painting

[Badger]

Hi, a few weeks ago I asked a question about hospital silencers. My engine is now out of the boat and away for a major service, head off, new cambelt, and tensioner, injector calibration, filters etc. Before removing the engine I ran it up and listened to the noise levels from diffent positions, and after ten years of ownership realised that a great deal of the decibels come from the exhaust, and not from the engine. With the engine bay empty, I had a close look at the silencer box which is woefully small. Also being ten years old I guess the baffles are rusted away anyway. I don't think I have room for a huge hospital type silencer, but do intend to move up to something bigger than the original. I have to do some homework, I have been told that silencers made for diesel engines are different than those made for petrol, does anyone know if this is correct ?.

Lastly I am cleaning up the engine bay, ready for a repaint of the bilges, the original paint never adhered to the floor and I have scraped back to the (shiny) steel. The battery terminals are nice and clean, but around the outside of the battery boxes there is a fair amount of the white powdery substance that you sometimes get on the terminals themselves. Is there a way I can stop these deposits from occuring, because that too eats through paint very rapidly, aswell as being very unsightly. Any advice /input from members will be gratefully appreciated.

 

Thanks Badger

[Swallowman]

Lastly I am cleaning up the engine bay, ready for a repaint of the bilges, the original paint never adhered to the floor and I have scraped back to the (shiny) steel. The battery terminals are nice and clean, but around the outside of the battery boxes there is a fair amount of the white powdery substance that you sometimes get on the terminals themselves. Is there a way I can stop these deposits from occuring, because that too eats through paint very rapidly, aswell as being very unsightly. Any advice /input from members will be gratefully appreciated.

 

Thanks Badger

 

Badger, the white deposit can be removed by washing the affected part with a fairly strong solution of sodium bicarbonate (baking powder) to neutralise the acidic deposits. Carefully wash off the residue with clean water and dry thoroughly. You should be left with a nice shiny surface which you can then paint with a good anti-corrosive primer and finish coat. Cover all the battery connections with Vaseline after doing up tight.

You then need to find out what caused the white deposit in the first place; usually from vapours arising from an over-charging generator over-heating the acid causing it to gas excessively.

Hope that helps.

[Badger]

Badger, the white deposit can be removed by washing the affected part with a fairly strong solution of sodium bicarbonate (baking powder) to neutralise the acidic deposits. Carefully wash off the residue with clean water and dry thoroughly. You should be left with a nice shiny surface which you can then paint with a good anti-corrosive primer and finish coat. Cover all the battery connections with Vaseline after doing up tight.

You then need to find out what caused the white deposit in the first place; usually from vapours arising from an over-charging generator over-heating the acid causing it to gas excessively.

Hope that helps.

Thanks for that, strange that the deposits build not on the battery terminals but outside of the battery boxes?..

[Sir Nibble]

The deposits are, I believe the result of the batteries being charged unthusiastically and blowing out acid vapour. Boiling water shifts it (and battery terminal corrosion) very well.

 

Silencers. This is not a motor being tuned for performance so I don't think you need be too precious about it. As far as I am aware, there is no difference between diesel and petrol silencers. They both work on the same principle to do the same job.

[WotEver]

As far as I am aware, there is no difference between diesel and petrol silencers. They both work on the same principle to do the same job.

 

There was a recent thread... hmm, found it, where it was suggested that most diesel silencers use a labyrinth as opposed to wadding, possibly because of back pressure, or more likely to do with wadding sooting up from the dirtier diesel exhaust. It doesn't appear that a definitive conclusion was made though.

 

The general opinion in a nutshell was that many petrol silencers incorporate wadding, but most diesel silencers don't.

 

Tony

Edited September 18, 2009 by WotEver

[Proper Job]

Thanks for that, strange that the deposits build not on the battery terminals but outside of the battery boxes?..

the vapour condenses on the closest cold surface. When the vapour is being formed as part of the charging surface the battery terminal is warm(?)

 

Regarding the silencer - what does the engine manufacturer recommend?

 

There was a recent thread... hmm, found it, where it was suggested that most diesel silencers use a labyrinth as opposed to wadding, possibly because of back pressure, or more likely to do with wadding sooting up from the dirtier diesel exhaust. It doesn't appear that a definitive conclusion was made though.

 

The general opinion in a nutshell was that many petrol silencers incorporate wadding, but most diesel silencers don't.

 

Tony

That thread wants to make the engine noisier. The OP wants it quieter.

 

Swap?

[The Bearwood Boster]

Take a look at Cowl silencers from IPU Group.(www.ipu.co.uk). They are based in the Midlands ask for Jonathan Hickman. I have no interest in IPU but have bought one of their silencers recently and it works well.

[nb Innisfree]

With any i.c engine you need to minimise backpressure, the easiest way to achieve this is to make silencer as large as poss, something that can't be done on cars due to space restrictions, hence their complex carefully designed exhausts.