72 Mercury 20 hp 200 lower unit removal

[Zaaap]

I read the post related to removing the lower unit on a 78 Mercury. That helped as the bolts/studs are the same here. I have the two nuts removed, but the unit does not budge. I am very concerned about damaging the unit, so... I'd like to confirm there are just the two nuts to remove and some pointers on how to actually pry/pull the unit. Thanks.

 

[Zaaap]

Correction, that was for a 79 Mercury. http://forums.iboats.com/forum/engi...rds/562653-79-mercury-20hp-lower-unit-removal

 

[Texasmark]

On smaller engines there is no "rear bolt" but on some there is. 20 hp may qualify. Do you have a zinc trim tab at the rear of the antiventilation plate, behind the prop? If so, unbolt it and remove it, taking note it's lateral position so that when you put it back, your steering will be as it was before....not pulling to one side or the other.

Look up in the recess under where the tab was mounted for a hex Allen bolt. If you have all this, removal of that bolt should grant your wish in separating the sections.

If not, then you must have a frozen drive shaft to engine crankshaft interface, which can happen especially if the drive shaft is carbon steel. I don't know when Merc gave up on that ridiculous design flaw and went like OMC had been doing for years, with a corrosion resisting stainless steel drive system. If the latter here is the case Google separating the lower unit from the mid section on outboard motors and you should get a lot of answers, many of which are addressed right here on iboats, or go to the iboats archives.

Good Luck

 

[Zaaap]

Still would like to know how, but using the string trimmer line up the telltale cleared it out and it's peeing ! Yay!

 

[racerone]

There are 3 fasteners to remove on them.

 

[Zaaap]

Do you know where the third is? I got the nut at the front of the motor under the swivel (about 3/5 of the way down the motor where the nut on top), the nut from the bottom just above the propellor (have to remove the cover plate with an Allen wrench). I didn't see any other fasteners. Thanks in advance

 

[Texasmark]

The others, if any are on the sides between the anti vent plate and anti splash plate (anti splash plate keeps water from running up the front of the mid section and into the boat.........as long as it is above the incoming water level while under way at any kind of speed.

 

[Chinewalker]

The Merc 20hp 200 has THREE studs. Two on the underside of the AV plate with one of those hidden by the anode, and the third come up through the front of the driveshaft housing, below the clamp bracket. You must remove the anode to access the rearmost nut.