Good evening everyone.
Have a 2011 Larson with a 4.3L/Alpha 1 drive. Bought the boat new, and the impeller has been replaced twice. Most recently was replaced this spring with an SEI kit, and the quality seemed to be equivalent to the Mercury part I installed three years prior.
No running issues until today when I was on the way back to the dock.. After two minutes at WOT temperature alarm went off and the gauge was around 225 degrees, so I immediately backed off the throttle. Once the RPMs came down temperature dropped rapidly to 150, and then slowly moved back to 175 where it normally runs. Tried running at 4,000 RPMs and temps stayed at 175, but at 4,700 RPM WOT temps started quickly rising after about 45 seconds.
Best guess is that it's somehow sucking air which causes the temps to rise quickly, but as RPMs come down it starts sucking water again and it quickly cools down with the thermostat wide open. This boat goes on plane at 2,600 RPMs, and it spent over 2 hours on plane today with no temperature issues whatsoever. If the seal between halves of the seawater pump were imperfect, wouldn't it suck air whenever the boat was on plane? If that's not the cause, what would cause it to act up only at 4,700+ RPMs?
Have a 2011 Larson with a 4.3L/Alpha 1 drive. Bought the boat new, and the impeller has been replaced twice. Most recently was replaced this spring with an SEI kit, and the quality seemed to be equivalent to the Mercury part I installed three years prior.
No running issues until today when I was on the way back to the dock.. After two minutes at WOT temperature alarm went off and the gauge was around 225 degrees, so I immediately backed off the throttle. Once the RPMs came down temperature dropped rapidly to 150, and then slowly moved back to 175 where it normally runs. Tried running at 4,000 RPMs and temps stayed at 175, but at 4,700 RPM WOT temps started quickly rising after about 45 seconds.
Best guess is that it's somehow sucking air which causes the temps to rise quickly, but as RPMs come down it starts sucking water again and it quickly cools down with the thermostat wide open. This boat goes on plane at 2,600 RPMs, and it spent over 2 hours on plane today with no temperature issues whatsoever. If the seal between halves of the seawater pump were imperfect, wouldn't it suck air whenever the boat was on plane? If that's not the cause, what would cause it to act up only at 4,700+ RPMs?