Possible leaking silencer

[rayjones]

I have a 2014 33 with a 28 HP saildrive
I have recently replaced the hull anode that extends to the area where the silencer
is. I am convinced that the anode bolt is not leaking so that only leaves the silencer,
although I cannot see where the water is coming from.
I am sure that the silencer is leaking as the pool of water worsens after running the
engine.
I am a concerned that it could be leaking after a relatively short period of time.
Is the original silencer as unreliable as it would appear?
Has anyone replaced a silencer? Any tips and which one to go for as I understand
that the Vetus does a good job.
Thanks in advance
Ray

[dawntreader]

If you go to 'bavaria yacht help' and search on 'silencer' there are many posts on this topic. The Vetus alternative gets a 'thumbs up' too 

[Salty]

My Volvo silencer had been leaking for a while before I realised where the water was coming from, but by then the corrosion at one of the stainless steel end covers was such that it didn’t look like it could be economically repaired. Looking around at the alternatives, I saw that the chandlery firm ForceFour offered various plastic silencers. The least expensive offering was one costing just under £60 (two years ago). I bought one, fitted it easily within the same space as the original Volvo job and since then it has worked very well indeed.
I could have left it at that and it would have been only just a little over half the price of its next nearest competitor, but being plastic I did worry whether it might not be up to the job, and so to ease my mind I also chose to fit a NASA exhaust temperature monitor. That increased my outlay by a little less than another £100, and would have been fitted irrespective of whose plastic silencer I used. So opting for one of the more expensive branded plastic silencers would not have removed my concerns.
Within the last two years since fitting my “cheapo” plastic silencer, it has performed entirely without fault, and from the monitoring device the temperature within the exhaust line about a meter aft of the water injection bend and before arrival at the new silencer has not exceeded 30 deg. C. Indeed most of the time it runs at around 26 to 28 deg C. The monitor provides peace of mind as well as a warning at what ever temperature I choose to set which currently is 35 deg.
One thing you should do whenever your boat is lifted is to ensure that the cooling water inlet through your sail drive is clear and free from any unwanted marine residents, mussel shells in particular, and that periodically you also check that your exhaust heat exchanger is clean and free from any blockages.

[rayjones]

Many thanks for your responses and apologies for not searching the forum! Lesson learned there!
Salty, I’m going to opt for the Force 4 and Temp Monitor option. Just one question, can I wire the monitor to the engine master switch? I understand that a 1 amp fuse is not to be ignored, but as the master switch is inches from where I need to be, this could make sense.
Thanks again

[Symphony]

Highly unlikely the silencer is leaking through corrosion. If you look at those that have failed it is after many years - mine was 9 years old and the boat had been on charter so had done 3500 hours before there was any sign of corrosion, and then caught it in time to repair it.

While there is value in having a temperature monitor if you think the engine is likely to overheat, a leaking exhaust will not cause overheating. The water is little more than hand warm when it gets to the silencer, and the amount leaking if any will be small. Equally there is little chance of a plastic one melting for the same reason.

 Water in that area needs proper investigation. I also have the same 33 but have not investigated around the silencer yet, but any leak will come from either the end caps of the hose attachments. It will be salt water. If the water is not salt but fresh then it will have come through a leaking deck fitting or more likely the plumbing to the deck shower. That is easy to check through the hatch in the aft cabin bulkhead.

[Salty]

My boat, a Bavaria 36 from 2002 with an MD2020D engine had also been used on charter for the first part of its life, until a wholly avoidable collision caused by totally inept charters, prompted me to remove my boat from the charter firm and from charter work. So it too had quite a number of engine hours on the clock and more than 14000 nautical miles under the keel by the time in early 2016 when the exhaust silencer was changed. Corrosion was the problem on the aft stainless steel end cover where this was the low end where sea water would collect and remain while the boat was moored. The problem here is that the atmosphere within the silencer above the water was essentially devoid of oxygen, and the remaining seawater became stagnant, thereby removing the much needed oxygen from the internal surface of the stainless end cap. Stainless steel in such conditions suffers from rampant corrosion resulting in numerous pinholes through the internal underwater area of the end cap. Plastic should not suffer from that problem. However, it does seem strange that your exhaust should be leaking on a boat only four years old, unless it has had very little use and a lot of idle time to allow the water inside it to become stagnant.
As Symphony says, water in that area needs thorough investigation to see where it is coming from, so it would be worth lifting the cushions and the boards from under the bunk to investigate, preferably while the engine is running so that you can see if it’s coming from the exhaust system, and with a carbon monoxide detector very close by to warn you to get out if there is leakage of exhaust gas. Put your CO detector under the bunk boards before you poke your head down so that it can warn you, and don’t hang around if CO is detected. Also have someone nearby who can help if you get into difficulties. Do be very careful. As an alternative and if you’ve got some blue tissue paper, before running the engine thoroughly dry the area and then lay in some of the tissue paper under the exhaust system. Run the engine briefly and then stop it, and the tissue will show you if the water is leaking from the exhaust system. Does the water taste salty, or fresh, as a simple taste test can very much narrow down what you are looking for.

[Salty]

.
.
 Just one question, can I wire the monitor to the engine master switch? I understand that a 1 amp fuse is not to be ignored, but as the master switch is inches from where I need to be, this could make sense.
.

Yes, that’s exactly what I did

[rayjones]

Thank you for your advice and warnings.
The water is salty. There are only two likely causes of water in this area, a leaking anode fitting or the silencer.
I,ve recently had the boat out of the water to replace the anode, and this alerted me to the problem.
The anode is definitely not leaking. I’ve dried the area and there is no sign whatsoever of water around the anode bolt, even when left for a few days. That only leaves the silencer. After more investigation there is a rusty mark under the silencer which seems to confirm that the silencer is the culprit. Equally, water only appears after running the engine. The two fittings are dry suggesting that the leak is coming from elsewhere on the silencer. The area is so restricted it’s very difficult to have a proper look. I’ve not tried the blue tissue test, but will today.
Thanks again.

[rayjones]

All sorted, thank you.
Blue tissue revealed a slow drip at the aft end of the silencer which quickened when
the engine was stopped.
Getting the silencer out was a faff as the engine blower and heating pipe work did
a really good job of concealing it.
Once out, hey presto, a leaking weld at the aft end. I’m guessing this can be repaired
so I won’t assign to the tip.
New ‘cheapo’ unit from force 4 in and all is well. In two minds whether to fit an exhaust
temperature sensor.
Anyway, thank you for all your help and advice. And good to meet you Moodymike.