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Hi all, i'm shouting to you guys over in the US because i'm stumped (probably because i'm a stupid european. 
)
OK, here's a puzzler.
I have an aging Mercury 2 stroke 20 HP outboard.
Serial No:- 9195125 (note this engine was made in Belgium) my research tells me that this engine was probably made in the late 70's (78)
at some point over the weekend it's decided that reverse sucks. when reverse is selected from the remote, the outboard just seems to rev as if she's in neutral.
However, if i look into the outboard well and select reverse the prop turns in the correct direction, and even stirs the water a little, but then adding any further revs just results in very quickly increasing the engine revs to ear splitting volume. and doesn't increase the thust.
With the engine off the boat i put it in forward gear and turned the prop (sparks disconnected) the prop turns the engine to the point where i cannot turn against the compression. (seems ok)
In neutral the prop spins freely.
In reverse the prop turns fairly freely with a bit more resistance than neutral (peaking at two points each rotation)
Observation is that the propshaft is turning, and not the propellor relative to the shaft. (this rules out bushes and sheer pins right? (I don't appear to have a sheer pin))
So conclusion is that i have a gearbox problem, and not something simpler, but what kind of problem?
Comments / suggestions?
)OK, here's a puzzler.
I have an aging Mercury 2 stroke 20 HP outboard.
Serial No:- 9195125 (note this engine was made in Belgium) my research tells me that this engine was probably made in the late 70's (78)
at some point over the weekend it's decided that reverse sucks. when reverse is selected from the remote, the outboard just seems to rev as if she's in neutral.
However, if i look into the outboard well and select reverse the prop turns in the correct direction, and even stirs the water a little, but then adding any further revs just results in very quickly increasing the engine revs to ear splitting volume. and doesn't increase the thust.
With the engine off the boat i put it in forward gear and turned the prop (sparks disconnected) the prop turns the engine to the point where i cannot turn against the compression. (seems ok)
In neutral the prop spins freely.
In reverse the prop turns fairly freely with a bit more resistance than neutral (peaking at two points each rotation)
Observation is that the propshaft is turning, and not the propellor relative to the shaft. (this rules out bushes and sheer pins right? (I don't appear to have a sheer pin))
So conclusion is that i have a gearbox problem, and not something simpler, but what kind of problem?
Comments / suggestions?
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