I've been fighting outboard difficulties ever since I got my boat..was going to bite the bullet and buy a new one after doing all the "simple" maintenance (it had no water pump impeller left when I got it, so it obviously has been overheated) because I didnt really want to go through a full rebuild on a 30 yr old 2-stroke. Carb rebuilt, gearcase oil changed, new water pump, plug wires, fuel buld and filter...it got better and better but it still just loses power over time, then shuts off. I did a little experiment yesterday...set it at a high idle, in gear, tied to the dock. I thought my experiment was going to fail, it ran for 30 minute or so before the rpms started slowly decreasing...ripping the cover off it was like the poor motor just screamed THANK YOU and it revved right back up to a bit higher than where it was. I dont really want to pull the gaskets off between the case and the motor (it tends to get wet in waves more than about 2') Any clever ideas for an intake from the outside, with water drain or something? It's an 82 mercury 180cc.
Suffocating O/B
- Thread starter Brian M H23
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If you have the money it's time to buy a new ob...
Why waste the time and money on a 25 year old outboard? It was obviously mistreated when you got it and things aren't going to make it better, you can't undo the years of abuse Buy a nice new 4 stroke with an electric start. It nice to have the reliability of something new, and it's easier to make the money to pay for it than to squander energy and resources on a old unreliable wreck. Anyway, the problem with your motor is: Something is blocking the air intake in the motor housing or something is touching and stopping the fuel or spark when you put the motor housing on. If it stops immediatly, it's the spark shorting out. If it takes a while to stop running then it's fuel or air. Could installing the housing somehow be engageing the choke? What happens when the motor cover is on loose? Most motor cowlings have a air vent at the top around the back handle or emblem.
Why waste the time and money on a 25 year old outboard? It was obviously mistreated when you got it and things aren't going to make it better, you can't undo the years of abuse Buy a nice new 4 stroke with an electric start. It nice to have the reliability of something new, and it's easier to make the money to pay for it than to squander energy and resources on a old unreliable wreck. Anyway, the problem with your motor is: Something is blocking the air intake in the motor housing or something is touching and stopping the fuel or spark when you put the motor housing on. If it stops immediatly, it's the spark shorting out. If it takes a while to stop running then it's fuel or air. Could installing the housing somehow be engageing the choke? What happens when the motor cover is on loose? Most motor cowlings have a air vent at the top around the back handle or emblem.
breathe
the cowl cover already has an air intake somewhere, probably right in the handhold spot to tilt it up. It's probably plugged. See if you can locate and clear it.
the cowl cover already has an air intake somewhere, probably right in the handhold spot to tilt it up. It's probably plugged. See if you can locate and clear it.
Not sure about an '82, but...
Back in the day, the coils would get hot and the insulation would break down. The resulting shorts would weaken the spark until the engine would quit. after cooling down, it would run fine...for a while...Taking the cowl off would allow cooling air which would improve things. Very hard to track down this problem, just something you had to know.
Back in the day, the coils would get hot and the insulation would break down. The resulting shorts would weaken the spark until the engine would quit. after cooling down, it would run fine...for a while...Taking the cowl off would allow cooling air which would improve things. Very hard to track down this problem, just something you had to know.
I agree with Chris check the ignition coil as a
last ditch effort. If a replacement does not correct the problem you have a loss of compression at running temperature and it would be about time to get a new one.
last ditch effort. If a replacement does not correct the problem you have a loss of compression at running temperature and it would be about time to get a new one.
Either find clog or drill some holes
Were it me, I would look real close to find the intake opening and make sure it is open - sounds like it is running out of air - because it revs up when cover is removed. Bad coils would not revive that quickly. If you can't find any clogged opening, then I'd drill some holes in the cover somewhere water isn't too likely to splash in. Cheaper than a new outboard.
Were it me, I would look real close to find the intake opening and make sure it is open - sounds like it is running out of air - because it revs up when cover is removed. Bad coils would not revive that quickly. If you can't find any clogged opening, then I'd drill some holes in the cover somewhere water isn't too likely to splash in. Cheaper than a new outboard.
Over heat
Since you are SURE that is was overheated once it might be the case that the water inlet, block or exhaust are either clogged or coated with scale. Salt water DOES NOT like to be boiled and not leave its mark on things. I doubt it is an air intake problem as it still stops even with the cover off.
Since you are SURE that is was overheated once it might be the case that the water inlet, block or exhaust are either clogged or coated with scale. Salt water DOES NOT like to be boiled and not leave its mark on things. I doubt it is an air intake problem as it still stops even with the cover off.
Don't buy a new one just yet
Most 30 year old 2 cycle outboards are just broken in. It would help if you told us what engine you have (make, yr & hp). Your symptoms point to an exhaust leak that fills the space under the cowl with exhaust gas that displaces the oxygen needed for combustion. To confirm try running it with the cover off. A great source for diagnosis & help can be found at iboats.com. Post your problem in the section for the manufacturer of your engine. Don't give up just yet. As to the overheating - what compression are you getting? That will give you an indication of damage done if any.
Most 30 year old 2 cycle outboards are just broken in. It would help if you told us what engine you have (make, yr & hp). Your symptoms point to an exhaust leak that fills the space under the cowl with exhaust gas that displaces the oxygen needed for combustion. To confirm try running it with the cover off. A great source for diagnosis & help can be found at iboats.com. Post your problem in the section for the manufacturer of your engine. Don't give up just yet. As to the overheating - what compression are you getting? That will give you an indication of damage done if any.
Other causes
When you first cracked the cover did it immediately increase revs, or did it take a little while? If the change was immediate, then you have an intake blockage - if the change was more gradual, I suspect something is overheating with the cover on and that the heat dissipates with the cover off. Almost 30 years ago we had a 2-stroke that was acting like yours - started and ran OK for a while, then gradually lost power and quit. Turned out to be a cracked cylinder head that was releasing ocmpression and leaking coolant as the motor warmed up. As long as it was relatively cool, it ran fine.
When you first cracked the cover did it immediately increase revs, or did it take a little while? If the change was immediate, then you have an intake blockage - if the change was more gradual, I suspect something is overheating with the cover on and that the heat dissipates with the cover off. Almost 30 years ago we had a 2-stroke that was acting like yours - started and ran OK for a while, then gradually lost power and quit. Turned out to be a cracked cylinder head that was releasing ocmpression and leaking coolant as the motor warmed up. As long as it was relatively cool, it ran fine.
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