Exhaust advice please

stav

stav

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Westerly conway with Mercedes om636 42hp.

I noticed whilst working on the oil pressure sender the rubber exhaust hose was showing signs of delaminating on the outer layers just down from where the water is injected. However the whole thing seems quite solid. Anyhow whilst in the UK bought 5M 2" diameter hose from hyphose in Poole whilst over in the UK for Xmas.

However feeling concerned about just changing it as the exhaust simple drops down from the engine then rises up with a small loop at the transom and then exits with no water traps or mufflers etc.

So should I leave it alone? Or what I was going to do was new pipe with a higher loop, but might the extra pipe introduce just a bit too much water and risk damage to the engine?

Or should I fit an exhaust water trap? Such as:http://www.asap-supplies.com/marine...centek-vernalift-inline-grp-waterlock-1500042

But I am not sure how much space there is but will have a look over the weekend whilst removing the injectors!

Finally at the moment it simply exits out of the stern via an elbow and skin fitting in the transom above the water line. But I was thinking about adding a 2" gate valve so it could be shut in extremes, but could I building a brass check valve in to the system,
http://www.ebay.co.uk/itm/BRASS-CHE...Domain_3&var=600054022656&hash=item4606e937bc

or would this give too much back pressure?

Any thoughts or ideas gratefully accepted. Just want to mention I am keen to change the exhaust as the kids play for extended periods in the aft cabin and have no idea of the age of the current hose and am concerned about it splitting and poisoning anybody in the cabin?

Thanks in advance.
 
You really should have a waterlock in the exhaust. In view of the fact you've bought 5 metres of pipe, you need to plan the waterlock location carefully. There's a lot of good advice in the Vetus catalogue - see page 68 (you can view it online). Any sort of constriction, such as the brass valve you've illustrated, is a complete mistake.
 
Thanks for the replies,

I like the idea of a water lock, but whether I can afford it (or can I afford to not be with it....) However, Rossyant, I am inclined to agree a water lock might be totally necessary as in reality the exhaust outlet is only 12" or so above a the water injector elbow so I guess in reality water dropping back into the system is only that amount.

I will have a measure up to see if I can fit the water lock and will look at changing the skin fitting for one with a flapper valve.

As is have taken the injectors out and have more on to other things to solve: damaged spill pipe nozzle (not me) but explains why it is leaking.

Thanks again
 
be very very careful with any changes ,or replacement.

the exhaust is highly likely to have one exhaust valve open on the engine when not running, and any water getting sloshed back into a pot (even a teaspoon full) can do a lot of damage
 
Not sure why you want to change anything. It has worked for 40 odd years without any problems. A water trap would be a useful addition as it will reduce noise a bit and give added protection in the unlikely event of water getting past your loop. It also provides extra capacity for the water in the system to drain into.
 
Thanks again for these replies, the main reason for thinking about changing is the outer layer coming off the exhaust rubber, but in reality the old hose seems twice as thick as the new. I was also looking for a way to improve the system re water tightness if caught in bumpy water.
 
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