Just purchased a 1986 pontoon boat with same year Mercury Classic 50 (45 horse 2 stroke outboard). Boat is still on same body of fresh water and has never been run in the ocean.
The motor is overheating after about 1 minute at idle with ears attached. Not exactly sure to what extent the overheat problem is as I am a boater newbie and have no experience whatsoever with outboards. I also do not know the exact temperature, but will be getting a non-contact thermometer shortly. The following work has been performed by a friend of mine who is pretty versed in Johnson/Evinrude motors... Replaced water pump as a kit. Old impeller had one remaining vane, so it was spent... fished out some of the old pieces from the lower unit and verified it was clear (Steam coming off of the motor is what prompted the pump replacement in the first place). After pump replacement the tell tale had a steady stream coming out, but the water is about the temp of a cup of fresh hot coffee and possibly hotter. The water jacket got hot very quickly to a point where it was too hot to touch the plate within a minute at idle. Next step... removed water jacket and exhaust baffle to visually verify no other obstructions. Seemed pretty clean. Blew compressed air through all water supply holes and up the copper water pick up tube, no verifiable debris in the channels. There is no thermostat on this model, so that removes an obvious failure. There isn't so much as a drop of water coming from the exhaust vent outlets just above the lower unit, but I've read that there doesn't have to be water coming out the exhaust, just the prop and tell tale which is the case with my motor. My friend thinks that he did not seat the copper pick up line properly after re-installing the lower unit and doesn't recall seeing a rubberized fitting for the end of the tube to seal it. My question is this... If in fact the copper water pick up tube is not seated and sealed properly, would this cause the pump to not be able to get enough water through the cooling channels to adequately cool the motor and run the risk of overheat damage? Thanks for your time and knowledge.
The motor is overheating after about 1 minute at idle with ears attached. Not exactly sure to what extent the overheat problem is as I am a boater newbie and have no experience whatsoever with outboards. I also do not know the exact temperature, but will be getting a non-contact thermometer shortly. The following work has been performed by a friend of mine who is pretty versed in Johnson/Evinrude motors... Replaced water pump as a kit. Old impeller had one remaining vane, so it was spent... fished out some of the old pieces from the lower unit and verified it was clear (Steam coming off of the motor is what prompted the pump replacement in the first place). After pump replacement the tell tale had a steady stream coming out, but the water is about the temp of a cup of fresh hot coffee and possibly hotter. The water jacket got hot very quickly to a point where it was too hot to touch the plate within a minute at idle. Next step... removed water jacket and exhaust baffle to visually verify no other obstructions. Seemed pretty clean. Blew compressed air through all water supply holes and up the copper water pick up tube, no verifiable debris in the channels. There is no thermostat on this model, so that removes an obvious failure. There isn't so much as a drop of water coming from the exhaust vent outlets just above the lower unit, but I've read that there doesn't have to be water coming out the exhaust, just the prop and tell tale which is the case with my motor. My friend thinks that he did not seat the copper pick up line properly after re-installing the lower unit and doesn't recall seeing a rubberized fitting for the end of the tube to seal it. My question is this... If in fact the copper water pick up tube is not seated and sealed properly, would this cause the pump to not be able to get enough water through the cooling channels to adequately cool the motor and run the risk of overheat damage? Thanks for your time and knowledge.
I have a shop manual on the way to me, so I'll be sure to reference the pipe plug and work with my friend on your suggestion as part of the troubleshoot. Regards.