How to reinstall lower unit on Merc 75

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billyboy72

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Nov 12, 2008
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17
My SELOC book is not much help. My engine is a 1986 75 hp. 2 cycle 4 cylinder engine. S/N A169082. Have rebuilt water pump and having a problem to shift gears after installing the unit to the engine. Alignment problem I think.
Can someone please give me the correct procedure that I can understand. Like, how can I tell which gear the lower unit is in so that it matches up with upper unit shift shaft?. Please help!!!!!! thank You, billyboy210.
 
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Chris1956

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Mar 25, 2004
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27,158
Re: How to reinstall lower unit on Merc 75

Put the control in neutral. Now turn the shift shaft with a plier (gently so as not to mess up the splines) until the LU is in nuetral. It will click in.

Now grease the driveshaft and shift splines and shove the LU up and into the midsection. Align the water pipe using the white plastic tube, now turn the flywheel with your hand until the driveshaft aligns. Now move the upper shift shaft with a needlenose plier until it mates with the shift shaft. Some motors have a molded plastic block that fits in the midsection to hold the shiftshaft in the proper position. If you have one of these make sure is stays in the msection.
 
The_Kid

The_Kid

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Apr 18, 2008
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Re: How to reinstall lower unit on Merc 75

When the lower unit is in neutral you should be able to spin the prop in both directions.
 
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billyboy72

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Re: How to reinstall lower unit on Merc 75

Hey Chris and (the Kid). thanks a million for the great advise. If the lower un is ok I'm sure iI can put it back like you both are telling me. Like they say. If you fail the first time, try, try again. thanks again.
billyboy72
 
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billyboy72

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Re: How to reinstall lower unit on Merc 75

Hey chris---
sorry to be slow, but which way do I turn the shaft until it clicks into neutral? billyboy72
 
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Chris1956

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Mar 25, 2004
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27,158
Re: How to reinstall lower unit on Merc 75

To go from forward to neutral turn the shift rod CCW looking from above the LU. To go from reverse to neutral is CW.

In forward the propshaft will turn CW and rachet. In reverse the propshaft will only turn about 1/2 turn in each direction, before the driveshaft starts to turn.
 
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billyboy72

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Nov 12, 2008
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Re: How to reinstall lower unit on Merc 75

thanks Chris;
will do as you say soon as the weather here is warmer here in New Hampshire.
20 degrees here today. too cold to work outside. thanks again. billyboy72
 
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