¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. Lagooncatowners
  2. Topics

Yanmar 40 hp/SD50 seawater leak

Bruce Wacker
 

My starboard engine ends up with the cavity underneath the engine full of seawater and overflowing into the bilge after an hour or two motoring at 2300 rpm. I thought it was the salt water pump, but had it rebuilt and there's no evidence of water around it. The water outlet from the sail drive looks dry and no apparent leaks in the hoses to and from the heat exchanger. No water collects when docked, so I think the SD membrane is OK.

Any ideas where water might be coming from the bottom of the engine so as to end up in the cavity underneath or, possibly, from the forward part of the sail drive which would drain into the cavity?
 

¿ªÔÆÌåÓý

It's probably the sail drive rubber seal between the hull and sail drive unit?
Usually there is a double seal with an electronic sensor that would give you warning of a problem.
Best have the problem looked at with boat out the water
Regards

Dean

On 25 Apr 2019 03:29, Bruce Wacker <wackerb@...> wrote:

My starboard engine ends up with the cavity underneath the engine full of seawater and overflowing into the bilge after an hour or two motoring at 2300 rpm. I thought it was the salt water pump, but had it rebuilt and there's no evidence of water around it. The water outlet from the sail drive looks dry and no apparent leaks in the hoses to and from the heat exchanger. No water collects when docked, so I think the SD membrane is OK.

Any ideas where water might be coming from the bottom of the engine so as to end up in the cavity underneath or, possibly, from the forward part of the sail drive which would drain into the cavity?

 

It could also be the raw water hoses from seacock to strainer and to engine. I had a bearly visible cut in the hose just where the hose connects to the strainer with the clips that built overtime due to vibration. Once I stopped the engine the strainer emptied (a small amount of water only) it stopped leaking. Have a look and maybe clean the engine room and run the engine in neutral and monitor.?

It could also be in the exhaust system as the pressure pushes out the water overboard at high rpm under load.?


--
¡ª-
David
Bruce Wacker
 

Thanks for the great suggestions. After cleaning and placing paper towels to show water it turned out to be spurting out of the overflow tube that goes to the top of the vacuum breaker on the sea water outlet to the exhaust. So, despite my fears of haul out (which isn't available where I am in New Zealand) and a big bill it boiled down to removing two very small screws to expose the diaphragm and push it down a few times. I couldn't even see the dirt that was breaking the seal!!! Working fine now:) I did find and test the SD seal sensor, so all is well at Adele Island, New Zealand:).
 

Hi Bruce,

I will explain what had happened to me. There is an inox curve about 20cm starting from the engine side, connecting the engine with the pipe going to the exhaust tank. There was a very small leakage from the downside of this inox curve. To see if this is the cause you definitely need to remove the pipe and have a close look.
I hope that might help.

BR?

MIke

1 - 5 of 5