I had a 200hp Mercury Optimax rebuilt back in about 2020 give or take a year or two. There have been a few issues since I've owned it. A few of the issues are 1, magnet came off foam float in engine mounted oil tank, water if fuel, and a overheat condition when first started. With the overheat associated with the initial startup at launch, I found that if I shut the engine down and then restarted it, that the overheat conditon would go away and not happen again through the rest of the day.
New this year, a slightly different overheat condition. We were headed out and then I got a constant alarm, but no alarm at the dock like normal (which shouldn't be "normal"). I immediately shut the motor down not knowing what the problem was at that moment. Started my Evinrude kicker to get us out of the channel and out on the lake far enough that I could let the boat drift while I looked for my paperwork regarding alarm sounds. This alarm was constant. At the time I didn't even think to check out Vessel View on my phone. Anyway, after reading up on the alarms, it could be a few things. I opted for an overheat condition rather than no oil since oil tank had about 2 gallons in it and it had a new motor mounted oil tank. So, I restarted the Opti, no alarms and everything was normal on Vessel View, engine ran fine. On Vessel View, I monitor, RPM's, MPH, engine temperature, gallons, and voltage, in that order. The engine has about 48 hours since the rebuild (Total Hours 737.1). Late that day after engine had been shut down for a while, we started it up and began heading back at a little about idle. Went for a few minutes like that, then the constant alarm went off, I immediately shut the engine down due to the alarm. Then thought I should have checked Vessel View. I restarted, immediately had the alarm and a engine temp of 187 degrees F. I released the drive and revved up the engine and temperature immediately dropped back to its normal range and never sounded an alarm again that day.
So, I figured a weak or damaged water pump. Today I dropped the gearcase and rebuilt/changed the water pump. There was no damage to the old impellor. Reassembled the water pump with all new parts, and reinstalled gearcase to engine. Started it up to test run with muffs. Everything appears to be fine so far. Engine temp never rose above 97 degrees F. with the engine shut down, my water pressure didn't force any water out the little water pump indicator, but with the engine running, it seemed there was a more powerful stream coming out of the valve/port on the back of the engine. I have heard of the water pump impellor taking a set, but I've never seen or experienced it. I'm thinking that might have been my problem over the last few years, but this year was worse. What are anyone's thoughts on these overheat conditions.
One other question, on the nose/front of the gear case there four holes which allow water to spray out while on muffs which is understandable. Can anyone tell me why Mercury recommends not running this engine longer than 5 minutes on muffs. Is it because this could cause the engine to starve for water while on muffs if water pressure isn't turned on high enough? Pressure and volume aren't a concern here. I realize if I'm underway water pressure on the nose would increase thusly increasing water pressure to the water pump. Never had a gearcase on my Evinrude's or Johnson's with hole/ports to allow water in. It may have to do with the horsepower or number of cylinders. The 175hp Evinrude (6 cylinder like the Optimax) I replaced with the 200hp Optimax didn't have this setup and the Evinrude never overheated. Sorry, this is so lengthy
New this year, a slightly different overheat condition. We were headed out and then I got a constant alarm, but no alarm at the dock like normal (which shouldn't be "normal"). I immediately shut the motor down not knowing what the problem was at that moment. Started my Evinrude kicker to get us out of the channel and out on the lake far enough that I could let the boat drift while I looked for my paperwork regarding alarm sounds. This alarm was constant. At the time I didn't even think to check out Vessel View on my phone. Anyway, after reading up on the alarms, it could be a few things. I opted for an overheat condition rather than no oil since oil tank had about 2 gallons in it and it had a new motor mounted oil tank. So, I restarted the Opti, no alarms and everything was normal on Vessel View, engine ran fine. On Vessel View, I monitor, RPM's, MPH, engine temperature, gallons, and voltage, in that order. The engine has about 48 hours since the rebuild (Total Hours 737.1). Late that day after engine had been shut down for a while, we started it up and began heading back at a little about idle. Went for a few minutes like that, then the constant alarm went off, I immediately shut the engine down due to the alarm. Then thought I should have checked Vessel View. I restarted, immediately had the alarm and a engine temp of 187 degrees F. I released the drive and revved up the engine and temperature immediately dropped back to its normal range and never sounded an alarm again that day.
So, I figured a weak or damaged water pump. Today I dropped the gearcase and rebuilt/changed the water pump. There was no damage to the old impellor. Reassembled the water pump with all new parts, and reinstalled gearcase to engine. Started it up to test run with muffs. Everything appears to be fine so far. Engine temp never rose above 97 degrees F. with the engine shut down, my water pressure didn't force any water out the little water pump indicator, but with the engine running, it seemed there was a more powerful stream coming out of the valve/port on the back of the engine. I have heard of the water pump impellor taking a set, but I've never seen or experienced it. I'm thinking that might have been my problem over the last few years, but this year was worse. What are anyone's thoughts on these overheat conditions.
One other question, on the nose/front of the gear case there four holes which allow water to spray out while on muffs which is understandable. Can anyone tell me why Mercury recommends not running this engine longer than 5 minutes on muffs. Is it because this could cause the engine to starve for water while on muffs if water pressure isn't turned on high enough? Pressure and volume aren't a concern here. I realize if I'm underway water pressure on the nose would increase thusly increasing water pressure to the water pump. Never had a gearcase on my Evinrude's or Johnson's with hole/ports to allow water in. It may have to do with the horsepower or number of cylinders. The 175hp Evinrude (6 cylinder like the Optimax) I replaced with the 200hp Optimax didn't have this setup and the Evinrude never overheated. Sorry, this is so lengthy
