What's the point of this?

[concentrik]

Here's a photo of the exhaust hose run from the water cooled manifold - on a BMW D35 engine. I thought the exhaust was meant to go directly down to the water trap. This does a huge loop up before exiting the engine comptmnt and then going right down to the trap.

It has clearly always been like this as there's only one hole in the bulkhead for the exhaust. The only possibility is that a PO has moved the water trap outside the engine compartment whereas before it was at the bottom of the loop shown.

Are there circumstances when this config is correct? It seems that the water pump needs to build a column of water which is highr than the engine!

 

[vyv_cox]

Bonkers! You can imagine water running back down the loop and finishing up in the engine. Especially if the engine is a little slow to start. The trap should be immediately down from the manifold.

 

[prv]

It seems that the water pump needs to build a column of water which is highr than the engine!

Not really, as the exhaust gas will push chunks of water up the pipe ahead of it, exactly as it does to get water out of the trap and over the swan-neck after it. However, as Vyv says, this installation is still pretty bad as it won't take much to overwhelm the tiny "trap" formed by the bottom of the loop of hose.

Pete

 

[concentrik]

Bonkers! ...... The trap should be immediately down from the manifold.

No exceptions - ever...? If so I shall re-fit it forthwith....

 

[oldharry]

A Swan neck was standard practice before waterlocks: if the boat is moored stern to the wind for any reason the repeated force of the waves can push water back up the exhaust through the engine, and can - has - sunk the boat, once the waterline goes over the exhaust outlet. Waterlock is designed to do the same thing - prevent water being forced back in to the engine. Would it prevent the boat from sinking if the exhaust gets covered? I dont know.

 

[Ben Dockrell 22]

A Swan neck was standard practice before waterlocks: if the boat is moored stern to the wind for any reason the repeated force of the waves can push water back up the exhaust through the engine, and can - has - sunk the boat, once the waterline goes over the exhaust outlet. Waterlock is designed to do the same thing - prevent water being forced back in to the engine. Would it prevent the boat from sinking if the exhaust gets covered? I dont know.

A sunken boat all for the want of a type of cover ?


Imagine an short angled plastic pipe type fitting which covers that hole with a vertical bend, just inside would be a ball which would be lifted by water to shut off the apperture if it got into it. think of a snorkel? The ball drops back immediately to let any gases escape when the engine is on.

 

[vyv_cox]

A Swan neck was standard practice before waterlocks: if the boat is moored stern to the wind for any reason the repeated force of the waves can push water back up the exhaust through the engine, and can - has - sunk the boat, once the waterline goes over the exhaust outlet. Waterlock is designed to do the same thing - prevent water being forced back in to the engine. Would it prevent the boat from sinking if the exhaust gets covered? I dont know.

I agree, but surely the swan neck was fitted close to the transom, so the low lying length of hose between it and the engine acted as a waterlock? Many boats still have them, mine would but a silencer is fitted instead of the final piece of hose before the skin fitting.

 

[Tranona]

Your Vetus should be directly down from the exhaust outlet - see the schematics in the catalogue. You are however, tight for room as it should be 30cm below the exhaust outlet.