25 Mercury 2 Stroke Running temperature
Jan 22nd, 2015 at 4:09pm Alert Board Moderator about this Post! Quote Remove
Blew up my 25 Merc 2 stroke not being careful putting around in the marsh. Had a good mechanic rebuild the entire motor top to bottom new water pump as well. I also had him put on an aftermarket temp sensor and alarm.
After the rebuild during the break in the alarm would go off after a min or so of running half throttle or two mins of putting around. We ran the motor with the mechanic and when the alarm we hit the motor with the Laser Thermometer. The exhaust jacket and everywhere the water jacket covers the cylinders was fine 130 degrees but the very small area at the top of the cylinders (where the temp sensor is) and in the small areas right around the spark plugs ( no water jacket there) was like 230 which is way hot. My question is does anyone know this motor well and know if those areas are designed to run hotter than the rest of the engine? I just want to make sure this engine is not running hot after the rebuild? We are taking the alarm off the motor since we think the motor is fine just the top and the small area around the plugs is designed to run hotter.
The really hot pee stream on these motors has always had me worried since I have only ran Yamaha in my life and their pee stream is noticeably cooler.
If anyone knows any mechs in town who are knowledgeable on these small mercury their contact info would be appreciated
They did alot during the rebuild but not sure they cleaned the water passages. I assume that since on the one spot on top of the top cylinder is getting hot and the rest of the motor is reg temp that water must be getting everywhere except for that area. is there anyway to clean the passages my self? Thanks Chris
Chris if the Motor was just rebuilt wouldn’t the head and head gasket be new? Ran the boat this weekend and only hit the exhaust area with the laser therm and it was in the 170s. the water pump was replaced and the thermostat turns on and off like it should? maybe I will try to flush the entire cooling system with vinegar or salt away?
Just my 2 cts worth but I agree with Chris v , pull head and re-clean
and install new gasket . Saw new gasket installed one time that some
how had a coolant passage hole not punched completly through.
LOL GW
all gave some , some gave all–only two offered to die for you, christ for your sins , the soldier for your freedom!!!
Just my 2 cts worth but I agree with Chris v , pull head and re-clean
and install new gasket . Saw new gasket installed one time that some
how had a coolant passage hole not punched completly through.
LOL GW
all gave some , some gave all–only two offered to die for you, christ for your sins , the soldier for your freedom!!!