Raw water jet in pipe outside companionway


Dean Gillies
 

Hi all
There is a small jet of water from the raw water cooling system which is ejected into the seawater drain pipe just outside the companionway door.  This has always been running since we bought the boat.  Recently, I've noticed that the flow has increased a bit, such that it now actually splashes up a little on to the teak floor plate.

I always tend to monitor for change, and I'm wondering if this increased flow rate is symptomatic of an impending problem?

Engine is running normally, coolant is 79C after motoring for an hour at 1580rpm today. Other temps measured around the engine all look normal.

Thoughts?

--
Dean Gillies
SV Stella *****,  Amel 54-154


Bob Grey
 

I have think the pipe enters the motor heat exchanger after this point then to the wet exhaust so either you have a partial blockage in either of these points or the flow through the gearbox heat exchanger has increased, this gearbox heat exchanger is prone to plugging with ribbon weed which can get through the filter, this weed is common in southern waters.


Dean Gillies
 

Thanks Bob, that helps .. so I guess this little pipe is some kind of anti-siphon mechanism for the wet exhaust. Plenty of water is coming out which means its working. The only reason I can think of that it would flow stronger is that there may be restricted flow from the anti-siphon take-off point to the hull exhaust exit.  Maybe I've got some growth at the outlet. I'll have a look at that next time I'm in the water.

Hope you are getting some headway with your engine problem. I live on Pittwater and have used Shane Douglas' services (Douglas Marine) for many years to look after my Volvo diesels. If you need a second opinion, his diagnostic skills are top-notch.
Cheers
--
Dean Gillies
SV Stella *****,  Amel 54-154


Bob Grey
 

Dean, was with Shane today and it’s his considered opinion it’s a cracked block, which reluctantly means looking for a new motor tomorrow. 

The exhaust outlet is above waterline so hard for growth. The ribbon weed blocks the gearbox cooler when fresh but will decay break up and move through the engine to the heat exchanger in smaller pieces. It’s when the anti siphon jet reduces you have to worry. I’ve had to clean the weed out about 4 times over 9 years as the flow decreased. I got 9 years and 3500 hours out of the motor, much lower than I expected but…..


Bob Grey
Renaissance III
Amel 55 #25


 

There are two ways to rig an antisiphon device:
  1. With a valve that mechanically opens when needed
  2. Without a valve and always open
In my opinion, Amel picked the best and most trouble-free method with #1 above because it can be totally neglected by the owner. 

With a valve, the following must be done regularly.
• For the air vent with valve, we recommend replacing the valve every 2 years.
• Regularly remove salt, rust, and dirt from all valve components and from the valve housing by rinsing out with clean water.
• Remove the cap (1) in order to take the valve out of the housing.
• Spray the valve components with a Teflon spray before refitting.
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CW Bill Rouse Amel Owners Yacht School
720 Winnie, Galveston Island, Texas 77550 
   

On Tue, May 24, 2022 at 6:19 AM Bob Grey via groups.io <renaissanceiii=yahoo.com.au@groups.io> wrote:

Dean, was with Shane today and it’s his considered opinion it’s a cracked block, which reluctantly means looking for a new motor tomorrow. 

The exhaust outlet is above waterline so hard for growth. The ribbon weed blocks the gearbox cooler when fresh but will decay break up and move through the engine to the heat exchanger in smaller pieces. It’s when the anti siphon jet reduces you have to worry. I’ve had to clean the weed out about 4 times over 9 years as the flow decreased. I got 9 years and 3500 hours out of the motor, much lower than I expected but…..


Bob Grey
Renaissance III
Amel 55 #25


Dean Gillies
 

Bob,
Sorry to hear about the motor. That's not great longevity as you say, but probably best to bite the bullet and replace it completely before you kick off on the circumnavigation.
Good luck.
--
Dean Gillies
SV Stella *****,  Amel 54-154
Soverato, Italy


Wolfgang Weber
 

Dean,
I had the same symptoms of splashing  and saw on an other Amel 54 that the venting/splashing pipe has a 90 degree little (10 cm ) downlooking pipe. So I think I lost this pipe and added  a flexible pipe . A little bit tricky by hooking up the straight pipe from the cockpit by 15 cm flexible pipe and the press the pipe down .
Wolfgang  SY Elise Amel 54 #162