Last owner changed replaced sterndrive with different gear ratio, like to switch back

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dgiles

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I have a 04 Mercruiser 5.0 carb that used to have a sterndrive with serial number OW505786 which I believe had 1.62 or 1.65. The guy before must have hit a rock or something and replaced the drive with serial number OM441966 which has a gear ratio of 2.0. I currently can run a 23 - 25 pitch prop, If it makes sense $$ wise, can I change the gear ratio back by changing the gears, or should I be looking to swap out the drives and at what cost are the gears?
 
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Don S

Don S

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Re: Last owner changed replaced sterndrive with different gear ratio, like to switch

You need the right gear ratio for your engine to work properly. bet you get slow starts and high rpm with not so great speed, even with those props.
The 2.0 is an odd drive. Have a look at this thread.
http://forums.iboats.com/showthread.php?t=471939
 
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dgiles

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Re: Last owner changed replaced sterndrive with different gear ratio, like to switch

I read the other thread and according to the gear ration chart, both the 2.0 and the 1.65 sterndrives both use 24-24 gear in the upper, but the lower changes from 14-28 to 17-28. Is it possible to switch the bottom gear or should I be looking for a complete bottom end?
 
Don S

Don S

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Re: Last owner changed replaced sterndrive with different gear ratio, like to switch

You need a complete lower unit.
The cost of the parts alone to change gears is about the price of a new SEI complete lower unit. Then to change gears, you need special tools to reshim the new gears, or pay labor for someone to reshim.
 
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dgiles

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Re: Last owner changed replaced sterndrive with different gear ratio, like to switch

New to I/O's and have never had one apart yet, so I apologize for my ignorance, but if I purchase a complete bottom end for a 1.62 (ie. with 17/28 gears, it should bolt up directly with my current upper drive correct? Whether it be SEI or Mercruiser? Lastly, I know you don't need to drain the oil to remove the complete sterndrive, but do I need to drain the oil to remove the bottom end.
 
scutly

scutly

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Re: Last owner changed replaced sterndrive with different gear ratio, like to switch

yes, drain the oil, your opening up the whole unit as opposed to just removing it. yes either Merc or SEI will bolt right up. otherwise Don S. wouldn't have told ya that's what you needed! lol SEI is an aftermarket company that makes exact replacement alpha drives. replace your raw water pump with a new full kit while you got it apart. oh and lastly definitively get a service manual.
 
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dubs283

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Re: Last owner changed replaced sterndrive with different gear ratio, like to switch

dgiles said:
I know you don't need to drain the oil to remove the complete sterndrive, but do I need to drain the oil to remove the bottom end.
Click to expand...

it would be in your best interest to first remove the entire drive unit from the boat, then drain the oil and split the halves

this will give you experience pulling your drive and inspecting all the transom assy components and allow you to pressure test the drive once you have it reassembled - not to mention its much easier than just dropping the lower half

you should pull the drive every year as part of the routine maintenance during winterization anyways

personally i NEVER drop just the gearcase off, i ALWAYS pull the whole drive unit - it gives you a better look into the whole system
 
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dgiles

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Re: Last owner changed replaced sterndrive with different gear ratio, like to switch

scutly said:
yes, drain the oil, your opening up the whole unit as opposed to just removing it. yes either Merc or SEI will bolt right up. otherwise Don S. wouldn't have told ya that's what you needed! lol SEI is an aftermarket company that makes exact replacement alpha drives. replace your raw water pump with a new full kit while you got it apart. oh and lastly definitively get a service manual.
Click to expand...
Do the new bottom ends not come with a new raw water pump?
 
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dubs283

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Re: Last owner changed replaced sterndrive with different gear ratio, like to switch

dgiles said:
Do the new bottom ends not come with a new raw water pump?
Click to expand...

depends, usually merc and sierra do - i cannot say for SEI though
 
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