Thepipdoc
Well-Known Member
Just thought I’d let you know the perils of not changing exhaust risers and manifolds as part of the regular service schedule!
Having bought my boat 12 months ago - a Searay Sundancer 270 with twin Mercruiser petrol 4.3L petrol engines and Alpha legs, I was a complete novice to boating but took to it instantly and so did my wife. We spent every weekend on the boat, and of course our annual holidays were spent afloat.
We have had various issues with it but to be fair the boat is 12years old and although it's only done 450 hrs, it’s becoming quite clear that parts will fail whether it’s done 450 hrs or 1,450hrs. I’m slowly working through replacing the various bits that I suspect could fail and if they do would land me with a potentially serious bill.
Unfortunately, since taking ownership I’ve had to lift the boat 3 times.... Once to replace a gear linkage cable from the port leg, another time to give both Alpha legs a full and proper service (bellows, bearings oils etc) and more recently to replace both of the risers and manifolds on the starboard engine.
Why lift the boat just to change the risers and manifolds I hear you ask..... Well, the reason was because the rubber flaps that sit in the “cowbell” that stop the water from flooding into the exhaust from the sea, had completely vaporised ( or so I thought, more on this later) and because there was nothing to stop water from flooding the boat and potentially sinking the boat, the mechanic quite rightly insisted that the boat should be lifted to ensure the work could go ahead in safety.
The reason the flaps had disappeared was because whilst out for a short trip one evening about 3 weeks ago we began to smell smoke. I thought the smell was from the land, possibly a garden fire ( we were about 400 yds from the coastline) but in fact the smell was from the engine bay on my boat. This became apparent when both engines suddenly stopped and the alarms started to sound. Smoke was billowing from the aft air vents and we were adrift heading for the rocks!
I won’t go into what happened next but as you can imagine I was using language like “flippin eck” and “gosh” .... not!
When the smoke had subsided and I was sure the heat had dissipated sufficient to open the engine bay hatch cover I was further surprised by the fact that the bilge had about 4 inches slopping about in it.
To keep the story fairly short, the boat was lifted and it soon became clear why the rubber bits on the starboard engine exhaust system had either melted or had tuned into charcoal was because of this:
See pics.
The channels where the cooling water is meant to flow were virtually non existent. The engine had begun to overheat and the rubber flaps had melted and the exhaust elbow rubbers were going the same way until both engines cut out. The fact that the engines stopped running probably saved the starboard engine from frying itself and saved me many thousands of pounds.
The rubber flaps and the stainless steel plates that and encased in them that I mentioned earlier were eventually found in the starboard leg. Sitting on top of the impeller housing!
Somehow they had managed to work their way through the cowbell waterway and would have remained in the leg had it not been for the mechanic insisting that the leg should be removed just to make sure the missing bits weren’t lodged in the leg housing.
At this point I still didn’t know if the engine had been damaged or not, and even though I had briefly started the engine several times after the initial breakdown I couldn’t be sure there was no damage till it was given a sea trial.
I’m very happy to report that the boat is back in the water and seems to be running as good as ever - fortunately.
On Monday I’m having both of the port risers and manifolds replaced and when that’s done both water pumps will be replaced. I don’t want any more issues with overheating engines!
And if you’re wondering why the bilge pump hadn’t removed the water that was flooding in through the exhaust elbow, this was because when the starboard engine had overheated the bilge pipe had partially melted (where it was touching the cowbell) and the pump as working but was only pumping water back in the bilge!
A bit of a long winded story, but if anyone out there is in two minds as to whether or not they should replace their risers and manifolds - err on the side of caution, otherwise little bill will very rapidly turn into BIG bill!
Having bought my boat 12 months ago - a Searay Sundancer 270 with twin Mercruiser petrol 4.3L petrol engines and Alpha legs, I was a complete novice to boating but took to it instantly and so did my wife. We spent every weekend on the boat, and of course our annual holidays were spent afloat.
We have had various issues with it but to be fair the boat is 12years old and although it's only done 450 hrs, it’s becoming quite clear that parts will fail whether it’s done 450 hrs or 1,450hrs. I’m slowly working through replacing the various bits that I suspect could fail and if they do would land me with a potentially serious bill.
Unfortunately, since taking ownership I’ve had to lift the boat 3 times.... Once to replace a gear linkage cable from the port leg, another time to give both Alpha legs a full and proper service (bellows, bearings oils etc) and more recently to replace both of the risers and manifolds on the starboard engine.
Why lift the boat just to change the risers and manifolds I hear you ask..... Well, the reason was because the rubber flaps that sit in the “cowbell” that stop the water from flooding into the exhaust from the sea, had completely vaporised ( or so I thought, more on this later) and because there was nothing to stop water from flooding the boat and potentially sinking the boat, the mechanic quite rightly insisted that the boat should be lifted to ensure the work could go ahead in safety.
The reason the flaps had disappeared was because whilst out for a short trip one evening about 3 weeks ago we began to smell smoke. I thought the smell was from the land, possibly a garden fire ( we were about 400 yds from the coastline) but in fact the smell was from the engine bay on my boat. This became apparent when both engines suddenly stopped and the alarms started to sound. Smoke was billowing from the aft air vents and we were adrift heading for the rocks!
I won’t go into what happened next but as you can imagine I was using language like “flippin eck” and “gosh” .... not!
When the smoke had subsided and I was sure the heat had dissipated sufficient to open the engine bay hatch cover I was further surprised by the fact that the bilge had about 4 inches slopping about in it.
To keep the story fairly short, the boat was lifted and it soon became clear why the rubber bits on the starboard engine exhaust system had either melted or had tuned into charcoal was because of this:
See pics.
The channels where the cooling water is meant to flow were virtually non existent. The engine had begun to overheat and the rubber flaps had melted and the exhaust elbow rubbers were going the same way until both engines cut out. The fact that the engines stopped running probably saved the starboard engine from frying itself and saved me many thousands of pounds.
The rubber flaps and the stainless steel plates that and encased in them that I mentioned earlier were eventually found in the starboard leg. Sitting on top of the impeller housing!
Somehow they had managed to work their way through the cowbell waterway and would have remained in the leg had it not been for the mechanic insisting that the leg should be removed just to make sure the missing bits weren’t lodged in the leg housing.
At this point I still didn’t know if the engine had been damaged or not, and even though I had briefly started the engine several times after the initial breakdown I couldn’t be sure there was no damage till it was given a sea trial.
I’m very happy to report that the boat is back in the water and seems to be running as good as ever - fortunately.
On Monday I’m having both of the port risers and manifolds replaced and when that’s done both water pumps will be replaced. I don’t want any more issues with overheating engines!
And if you’re wondering why the bilge pump hadn’t removed the water that was flooding in through the exhaust elbow, this was because when the starboard engine had overheated the bilge pipe had partially melted (where it was touching the cowbell) and the pump as working but was only pumping water back in the bilge!
A bit of a long winded story, but if anyone out there is in two minds as to whether or not they should replace their risers and manifolds - err on the side of caution, otherwise little bill will very rapidly turn into BIG bill!
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