Muffler questions

[Austinsailor]

As an old sailboater just crossing over I may ask some dumb questions, but - here we go.

I just bought a Seapiper, the smaller trailerable trawler. Took it out today for the first time. Short story is, broker and I both misunderstood the markings on the valve and left engine cooling water off. Temp just started to rise, saw our mistake, turned the water on. All is good for a few minutes until we realized there was steam coming from the engine room. Turns out, the muffler melted.

In my sailboat world my mufflers were all stainless, this would never have escalated beyond an “oops”.

Now, I need to replace the muffler and figure out how to keep this from happening again. After all, operator error is not the only reason this could happen. Jellyfish, plastic in the sea, loss of impeller parts and on.

On this boat the exhaust is so low you really can’t tell if there is water coming out. It seems to me I need an exhaust gas temp monitor of some sort, and an inlet water flow sensor of some sort. And maybe a stainless muffler, although my local yard says plastic and fiberglass are my choices. I did make my last one myself, but I’d rather not get involved in that again.

Any thoughts?

 

[rslifkin]

Don't just replace the muffler, replace any rubber exhaust hose in the entire system as well. It's all heat damaged most likely.

 

[koliver]

As an old sailboater just crossing over I may ask some dumb questions, but - here we go.

I just bought a Seapiper, the smaller trailerable trawler. Took it out today for the first time. Short story is, broker and I both misunderstood the markings on the valve and left engine cooling water off. Temp just started to rise, saw our mistake, turned the water on. All is good for a few minutes until we realized there was steam coming from the engine room. Turns out, the muffler melted.

In my sailboat world my mufflers were all stainless, this would never have escalated beyond an “oops”.

Now, I need to replace the muffler and figure out how to keep this from happening again. After all, operator error is not the only reason this could happen. Jellyfish, plastic in the sea, loss of impeller parts and on.

On this boat the exhaust is so low you really can’t tell if there is water coming out. It seems to me I need an exhaust gas temp monitor of some sort, and an inlet water flow sensor of some sort. And maybe a stainless muffler, although my local yard says plastic and fiberglass are my choices. I did make my last one myself, but I’d rather not get involved in that again.

Any thoughts?

I had a sea water hose blow. Didn't take long before the tone of the exhaust changed and got me down into the ER from the flybridge, to find the muffler melted and water in the bilge. The blown hose was between the Heat exchanger on the engine and the Transmission cooler. If the muffler hadn't melted, the transmission would have.
No exhaust gas temp monitor or inlet water flow sensor would have given prior warning. Replacing the hose and the muffler was far and away the best outcome.

 

[Comodave]

Fiberglass mufflers are pretty much the standard although you can get other materials.

I use an exhaust alarm system from Borel Mfg in California. It is a simple to install and great system. It will alarm well before the engine temperature starts to rise. You can also monitor things like Water In Fuel and high water. On our last boat I had exhaust temperature alarms on both mains and the genset, 2 high water alarms and 2 WIF alarms. Like I said it is an easy install and uses no power unless it is actively alarming.

 

[kapnd]

I had a sea water hose blow. Didn't take long before the tone of the exhaust changed and got me down into the ER from the flybridge, to find the muffler melted and water in the bilge. The blown hose was between the Heat exchanger on the engine and the Transmission cooler. If the muffler hadn't melted, the transmission would have.
No exhaust gas temp monitor or inlet water flow sensor would have given prior warning. Replacing the hose and the muffler was far and away the best outcome.

A flow sensor mounted in the rubber hose that feeds the exhaust mixing elbow will monitor the flow of the entire system up to that point.
The elbow can have a temperature alarm as well.
As mentioned above, stay alert to changes in exhaust noise!

 

[psneeld]

Don't forget to check/replace engine impeller run dry.

You could or already should have a vented loop in your water entering your mixing elbow which can have a water telltale piped to a convenient place to see water flowing after engine start. A flow detector can do the same thing.

 

[rgano]

A flow sensor, as mentioned, is fine, and a Borel exhaust temp alarm strapped to the exhaust hose before the muffler is dead simple to install as well. I have them on my generator and my main engine.

 

[TBill36]

You mentioned trailer, so I'm assuming you pull it out frequently. You will probably lose the raw water pump prime every time you pull it out. To prevent this you can close the intake valve prior to taking it out. I usually take my keys and put them by the valve if I've closed one that is required to be open. That way I can't start it without touching the valve.

 

[Keysdisease]

[QUOTE=Austinsailor; In my sailboat world my mufflers were all stainless, this would never have escalated beyond an “oops”.

On your sailboat the engine was an auxiliary, you're under power full time now. Stainless is not impervious to corrosion the way fiberglass is. Salt water mixed with hot diesel exhaust gas is a very corrosive environment and stainless will fail some day too, oops!

Fiberglass mufflers have been around at least 50 years now, and some of the early models are still working just fine.

With the proper safeguards a fiberglass muffler will serve you very well

$00.02