engine overheating

[thevdeub]

to put some context : I am a rookie and this is my first boat.
Got a Beneteau 43' from 92 with a Perkins Prima 50hp with 1000 hours.

now we went out a couple of time and motored without any issues for a dozen of hours (since we got the boat).


Last week, coming back to the marina, alarm rings and lot of white smoke.
did not think about dropping anchors, we made our way to the slip in 5-10 minutes. There was not water anymore from the exhaust.
Friends told me : Impaler or filter. Fine.
Today we check both. nothing wrong. we put the impaler back for a test. now everything is running fine (for 2 minutes, at the deck). well, i will change the impaler anyway, but still wondering : if nothing is wrong anymore, what happened ? i suppose i would have prefer something obvious, something broken.
Seaweed in the Intake ? got away by itself in the last couple of days ? simple overheating of the engine (too high ? did not remember being specifficaly aggressive and it ran literally for 5 minutes before the alarm beeped) ? Stuck impaler that does not show it and putting in and out solved the issue ?
The level of coolant seemed kind of low, but ive got hard time believing it s the issue as we motored with this for a dozen of hours two weeks ago.

Any help / opinion appreciated.

[celenoglu]

Since everything is fine now, it seems to be a blockage in the sea water intake. The most possible cause is a nylon bag blcing the sea water intake. Smaler particles are generally sucked by the impeller and are kept by the filter, but a layer of nylon bag or similar covers the intake from the outside and is never released before you stop the engine. although your impeller seems in a good condition, it might have over heated because no water was present. It is a god idea to change the impeller which might have been "burned" during the accident.

[thevdeub]

I see. We are sailing in SF bay, lot of floating garbage ...
If that happen again, what could be the best thing to do ? stop the boat and let the pressure go down to try to get ride of this ? any easy way to expel the water from the intake to push the blocking bag out ?

[Gene T]

It is a good idea to pay attention to the sounds your boat makes. Easy to tell when you lose water flow. The exhaust sound will change. That will happen way before the engine overheats.

If you loose water flow first thing is to look below and see if you have a leak. Then shut off the engine. Wait a min for the intake to clear and restart the engine. I have never had this happen but you could get a plastic bag in the intake. You will loose suction as soon as the engine is shut off. If you have water flow after starting the engine, you should know within a min of starting it then that was probably the problem. But: other things can happen. The impeller can slip on its collar and look ok but fail to pump. This generally happens on starting the engine however. You really need to run the engine up to temp and not just for a few min at the dock. Make sure your dock lines are good and run it in gear. How hard you push it is up to what you feel comfortable with but I have run it pretty hard in order to warm up the engine properly at the dock. Take the time to understand how the cooling system works. If you understand how your fuel system and cooling system work you will be able to troubleshoot your engine much more easily.

Gene