Yamaha 75HP 2 Strokes - drive shaft is seized into the crankshaft

[smanitos]

Hello everyone
I have a Yamaha 75HP 2Strokes from 1999, I want to replace the watter pump but the lower unit wont come out... I removed six screws and the Lower unit only opened 1/8'' (4mm). I guess drive shaft is seized into the crankshaft, what shoul I do, how can I solved? I would appreciate yourscomments.
Kind regards
Sman

[TownsendsFJR1300]

You did get bolt #9 out correct(under the trim tab)?:

https://www.boats.net/catalog/yamaha...casing-drive-2


When was the last time the LU was off and the splines lubed?

[boscoe99]

If all of the bolts are verified to be out I would reinstall just the six main bolts and leave them about a quarter inch from being tightened. I would then put flush muffs on the lower unit to feed water to the motor. I would then start and run the motor on the muffs for at least 20 minutes or so. Hoping that as the crank shaft heats up it will expand and not grip the drive shaft so tightly. Maybe the weight of the lower unit pulling down on the motor (you might want to help) and the vibration from the motor will help to break it free. If so, it will only drop down a quarter of an inch. When you see this you can stop the motor and see if you can finagle the rest of the drive shaft out of the crank shaft.

If that does not work, come back here for plan b.

[smanitos]

You did get bolt #9 out correct(under the trim tab)?:

https://www.boats.net/catalog/yamaha...casing-drive-2


When was the last time the LU was off and the splines lubed?

I I dont know, this outboard only as two years in "my hands" unfortunately thats a big surprise...

[smanitos]

If all of the bolts are verified to be out I would reinstall just the six main bolts and leave them about a quarter inch from being tightened. I would then put flush muffs on the lower unit to feed water to the motor. I would then start and run the motor on the muffs for at least 20 minutes or so. Hoping that as the crank shaft heats up it will expand and not grip the drive shaft so tightly. Maybe the weight of the lower unit pulling down on the motor (you might want to help) and the vibration from the motor will help to break it free. If so, it will only drop down a quarter of an inch. When you see this you can stop the motor and see if you can finagle the rest of the drive shaft out of the crank shaft.

If that does not work, come back here for plan b.

I next weekend If possible I will do your recomendation, thanks for your cooperation.
Kind regards

[smanitos]

If all of the bolts are verified to be out I would reinstall just the six main bolts and leave them about a quarter inch from being tightened. I would then put flush muffs on the lower unit to feed water to the motor. I would then start and run the motor on the muffs for at least 20 minutes or so. Hoping that as the crank shaft heats up it will expand and not grip the drive shaft so tightly. Maybe the weight of the lower unit pulling down on the motor (you might want to help) and the vibration from the motor will help to break it free. If so, it will only drop down a quarter of an inch. When you see this you can stop the motor and see if you can finagle the rest of the drive shaft out of the crank shaft.

If that does not work, come back here for plan b.

Hi Mr. Boscoe99

Thanks for your cooperation, I'm sharing photos to everyones who has the same problem. This work it looks hard but it isnt easy ... Looll

So, be pation, and never giveup !

Kind regards!

[pstephens46]

Always felt C-4 might break her loose too.

[boscoe99]

Congratulations.

Reminds me of the saying "an ounce of prevention (grease) is worth a pound of cure".

[robert graham]

Drop the lower unit once a year to inspect, clean and grease driveshaft splines....good preventive maintenance..

[smanitos]

Thanks Robert

[smanitos]

Congratulations.

Reminds me of the saying "an ounce of prevention (grease) is worth a pound of cure".

Thanks and kind regards