A few days ago I continued sea trials on my refurbished Mayflower 48 which has a Perkins
has 10 hours on it since the water
pump was rebuilt, the hoses and clamps checked and the engine panel was replaced.
Early morning I started the engine, checked exhaust
water flow at idle and high revs. Then shut it down to wait for the guests. While waiting I checked the oil
. Was between max and min as expected as it takes time for the oil
to drain to the pan after the engine runs.
I checked the water strainer, clean. The strainer is above the water line so I did not have to close the seacock.
Went sailing, was magnificent but rocky with swells 0.7 m.
Its open water outside the marine
breakwater, the fetch is to Italy
depending on wind
We returned to the breakwater, started the engine and dropped the sails
. The engine thermostat keeps the engine at 82 deg C but it quickly reached 91.
Unfurled the genny and headed away from the breakwater while I started the checks, engine in idle but temp climbing slowly.
is now below water most of the time due to the swells and without climbing onto the swim platform, its difficult to tell if water is coming out the exhaust.
I went below and saw that the rubber exhaust pipe was not overly hot, the plastic muffler
was not burned out and I could see water flowing in the clear wire reinforced pipe feeding water into the elbow
The fresh water reservoir was 3/4 full due to the water expansion. So no loss in cooling
water. The engine room was hot so not a sensor
My guess was reduced water flow or a heat exchanger
clogging problem, neither of which are easy to solve on a rocky boat
We sailed back to the marina, furled the genoa
and kept it ready to unfurl in case of engine problems at the
We headed slowly back to the marina and into the slip, temperature reached 99 deg C. Then shutdown the engine.
When the engine room cooled down I started the engine and saw there was NO water flow from the exhaust at idle and when revving. Shut down the engine. So there is a water flow problem but not severe enough to burn out the plastic muffler
I checked the water strainer, the cap was loose. The scupper pipe runs alongside the strainer and I mistook its friction on the cap for the cap being tight.
I had checked the water flow before checking the strainer but not after!
I secures the cap and started the engine. After a minute water out of the exhaust.
Conclusion, the seawater pump
was sucking air and water resulting in enough water to cool the exhaust but not enough to effectively cool the engine.
1. Check water flow from exhaust EVERY time you start the engine.
2. At what height should the strainer be mounted. Above the water line is convenient because no need to close the seacock and the strainer may act as a siphon break? My thinking is that it should be mounted so the lid is just above the water line and the body is below. In my case I can just see the water in the pipe just below the strainer. Time to relocate the strainer about 5" lower?
3. I am lucky that the powerful raw water pump
managed to pull enough water.
4. It's time to add a loud audible temperature alarm
. My new panel has this capability but its not yet connected.