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Newbie question -1984 Mercury 25 HP 2 stroke

S

sailscubasurf

Member
Hello, and thanks for adding me to the forum.

I recently purchased an 11 foot Avon RIB with a 1984 Mercury 25 hp 2-stroke.

I had the engine serviced (Plugs and water pump replaced, lower unit oil replaced, carb rebuilt) and the tech said that he saw a little leakage of water in the lower unit, but wouldn't go in and repair it because it would cost me more than the motor is worth.

To prolong the engine's life, he suggested I check the lower unit oil after every outing and if it looks milky, drain and replace with new oil.

My challenge is that the boat is in the water all the time, and I don't have a trailer or davits to pull it out of the water. Is it possible to drain and replace the oil while the engine is tilted up out of the water?

Also, is it possible to run the engine / fresh water flush it when it is tilted out of the water?

And one more question, I've noticed that when I am at low speed, and or idle, the engine occasionally misses. I timed it and it happens about every 2 minutes, but not on a regular basis. Any thoughts on why it would do this, and what I need to do to fix it (or should I just leave it alone?)

Gary
 
In replacing the impeller your maechanic was nearly there to replace driveshaft seals.----Propshaft seals are easy to replace too.------Now if it is a saltwater motor all bets are off !----Perhaps look for another mechanik too.
 
The occasional miss could be as simple as a bad spark plug. What brand of plugs did he put in? Sure don't like that leak if it needs checking every outing. Racer is right....you need to find a mechanic more realistic and fair, with enough skills to test lower unit for leaks....meaning a pressure and vacuum test....then replace the leaky seal which is likely either the shaft seal right there under the water pump, or the prop shaft seal. Ask questions here, where you can get an honest and accurate answer. Between the few techs reading this, you are likely to tap into many hundreds of years repair experience.
 
Miss could be just a maladjusted low speed jet in the carb.....set too lean.....screwed in too far. When you are through running slow, like in a nowake zone and leave the zone and are ready to get on plane and get going, assuming that you max out the throttle control (twist grip), does the engine take the throttle immediately, or is there some hesitation then you get solid power and it gets on up on plane? If it hesitates, that is another indication that the low speed jet needs to back out......just until it takes throttle.
 
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