Watery engine

[AndrewD]

My Beta BD662 engine (indirectly cooled) keeps filling up with sea-water! The problem seems to be that the exhaust system can hold enough water at the point when the engine is stopped, that the settled level is higher than the highest point of the exhaust outlet elbow, which in turn is constrained by being below the cockpit sole, so the surplus runs back into the manifold and thence through the valves into the cylinders. Bad! It doesn't happen every time; usually, I assume, the flow through the system is sufficient that the settled water level is lower and no run-back occurs. Is this unavoidable or does it point to a mis-sizing of the hoses, the waterlock, the height of the final syphon-breaker, or ??? Any thoughts anyone?

No sig is a good sig

 

[Strathglass]

Have You got a water trap in the exhaust system? or if you have one is it big enough to hold the water from the exhaust?

 

[Chris_Robb]

Do you have a siphon break in the exhaust circuit? If you do have one, is it working? When you stop the engine you should be able to hear the air bleeding back in to the system. Salt crystals can bung them up. This is vital if the engine is at or below the waterline.

 

[david_bagshaw]

my only thought, to add to the earlier posts, is if there is not enough room to install a large enough water trap, some sort of 3 way valve is needed just before the injection point to divert the water overboard while the throttle is blipped, to "dry the ehaust" before the engine is stopped. N

Is there sufficient of a swans neck in the system to stop seawater rolling in and to
keep it dry.

David B

See my web site www.yachtman.co.uk

 

[roger]

Betamarines instructions say air break should be 300 mm. above waterline. Vetus instructions say 400 mm. I was surprised how far down my injection point is compared with the water surface.

 

[oldharry]

This sounds a very unhappy state of affairs, and a recipe for early major engine failure - probably just at a time when you need it most! Seawater is devastatingly corrosive to the engine internals, and if it find its way into the oil sump (which it will sooner or later, if ithas not already done so) will rapidly destroy the bearing surfaces of the crankshaft and mains with terminal results. What its doing to the bores, rings and valve faces in the meantime is ... well!

You need firstly to find out whether the water is actually coming back from the exhaust to the engine as you think it is. The exhaust pipe should dip well below the manifold before rising to the swan neck, so that any water remains well clear of the manifolds.

If the engine is below the waterline, you must turn off the inlet seacock if the engine is not running. If not that could be where the water is coming from, seeping through the system and filling everything up while the engine is stopped? There are certain engine faults (cracked block, leaking head gasket, leaking manifold cooling gasket) which could allow coolant into the bores, but usually they will produce other symptoms like bad starting, power loss, odd whistling or wheezing noises etc.

Try the suggestion of turning the water feed to the exhaust off before stopping the engine to see if this really is the cause of the trouble.

But sort it now: your engine is suffering badly every time it happens!

 

[dick_james]

You need a swan neck to stop water gobbing back into the exhaust, A water trap below the injection point large enough to hold the contents of the exhaust hose and a (working) syphon break sufficiently higher than the water level. If you have all these then you will not have a problem. I agree with previous postee, fix it now.

 

[johnt]

have you calculated the potential volume of water in your exhaust pipe between the water lock and the hight point (goose neck)?

45mm hose = about 1.3L per metre (pi R2 X L, 1000cc=1L)

and how LOW is your waterlock? recommended height is 10 ins from centreline of lock to injection point

what capacity has waterlock? if its less than the pipe capacity its bound to cause trouble

never mind the rust.....it can bend a conrod ...and that gets very expensive on Betas

If all else fails........talk to Vetus on 023 80 67 2277