Engine water cooling query

[Cardo]

During our trip along the French coast (which was done mostly under engine as the wind was completely pants) I noticed a constant dribble of warm water coming out of a small outlet on the side of the boat whilst we were motoring along. I've followed this back to the engine and it comes from a small T from the cooling water outlet. The outlet has a T for this particular pipe and a further one for the stern gland before it joins with the gas exhaust and goes into the waterlock.

Two questions:

1) What is the purpose of this pipe?
2) Is there any harm in water dribbling out of it?

 

[Deleted member 36384]

I have a vague recollection that it is an anti syphon tube to stop water running back from the outlet. When the engine is running some of the water is forced out the T piece.

 

[theoldsalt]

1. The purpose of the discharge out of the side of the boat is a "tell-tale" for cooling water through the engine. This also indicates water lubrication to the stern gland.

2. If the dribble stops then it almost certainly means no cooling water through the engine and no stern gland lubrication, so it is important.

This "tell-tale" is sometimes fitted if the water cooled exhaust exits underwater or under an overhanging counter and so water flow is difficult to see/check.

 

[gasdave]

It is an anti-syphon outlet. On my boat a previous owner/engineer has led the "outlet" back to an accessible part of the engine bay where it now empties into a small plastic bottle which I empty at the end of each use (about a cupfull per hour of running).

 

[VicS]

1) What is the purpose of this pipe?
2) Is there any harm in water dribbling out of it?

If this "T" is in fact an inverted "U" at the highest point in the antisyphon loop then it is indeed coming from the antisyphon "valve" itself.

There are two common types of antisyphon device.
One actually has a small valve in it which opens when the engine is stopped to allow air to enter and break the syphon.
The other has no valve and discharges a steady small stream of water all the time the engine is running.

Yours is presumably the latter. Worry if the water stream stops!

 

[Cardo]

If this "T" is in fact an inverted "U" at the highest point in the antisyphon loop then it is indeed coming from the antisyphon "valve" itself.

There are two common types of antisyphon device.
One actually has a small valve in it which opens when the engine is stopped to allow air to enter and break the syphon.
The other has no valve and discharges a steady small stream of water all the time the engine is running.

Yours is presumably the latter. Worry if the water stream stops!

The T is indeed at the highest point of a sort of inverted U bend in the outlet pipe.

Thanks for the replies, all. I guess it works as a telltale to ensure water is coming through as when the boat is motoring at 6'ish knots the exhaust outlet, which is quite close to the waterline on the stern often becomes submerged.