1984 Mercury inline 6 cylinder 90hp motor "Tower of Power" ( is it worth fixing)

[Jimmy63]

1984 Mercury inline 6 cylinder 90hp motor "Tower of Power" ( is it worth fixing)

I am looking to buying my first boat (its used) the boat has this motor on it, the owner tells me the following, " The motor runs well, however something broke and the motor runs, but it is not turning the drive-shaft to the outdrive. I pulled the lower unit and Splines look to be in good shape, so possibly splines on the crankshaft are bad?" does anyone have any ideas as what could be wrong? is it the crankshaft? and is this worth fixing? He told me he has done the following repairs in the past few years " the Compression was very good 140 PSI on all cylinders. New starter, CDI switch boxes, carbs rebuild and re-jetted for ethanol containing fuel, also Just put a brand new 4 blade solas prop on the motor. any help would be greatly appreciated.
thanks in advance
Jim

 

[racerone]

What happens when you try and shift the lower unit to forward ?

 

[Jimmy63]

This what he told me " It shifts normally, but the prop will not spin when engine is running. When engine is running no water is being drawn through the engine. Lower unit shaft is not turning"

 

[racerone]

Does the lower unit itself work properly ?

 

[Jimmy63]

Yes. If the shaft is turned manually it works properly.

 

[racerone]

Maybe the crankshaft is broken or splines worn out.----Worth fixing ?----That depends on your ability / incentive and availability of used parts in your area.

 

[Jimmy63]

Racerone,
Thanks for responding!!! I do not have any experience fixing outboards and starting on a crankshaft wouldn't end well.... if the crankshaft is the only thing needed 1400.00-1500.00 to have it done is what a few people told me. at the point of having it apart what else would be a good idea to replace? so i am leaning towards this would be a parts motor. which i have no interest in parting out. so i quess i need to figure out what the boat and trailer is worth and make him an offer and look for newer motor to replace it.
thanks again for your help
Jim

 

[Chris1956]

$1400 is way too much to pay for a repair. I would drop the gearcase and inspect the crankshaft splines. Perhaps something else is wrong. If not, it is a parts motor, IMHO