MERC 500 Lower unit TOOLS

[crem1]

Which tool is absolutely a must have to disengage the prop shaft successfully? Where do I get one?
Thanks

 

[lindy46]

Re: MERC 500 Lower unit TOOLS

You need a spanner to remove the prop shaft nut/cover. They occasionally appear on Ebay. Do a search for "Mercury outboard tools". Sooner or later you'll find one. They're not cheap. Mine cost me about $50 with shipping.

 

[crem1]

Re: MERC 500 Lower unit TOOLS

Thanks Lindy

 

[Texasmark]

Re: MERC 500 Lower unit TOOLS

What do you want to do? Do you want to remove the prop and then remove the propshaft from the engine? Or do you just want to remove the prop?

First of all, what year is your engine?

To remove the prop, any deep socket that fits the nut will do that.

If you want to remove the prop shaft/assy and it is an older engine then yes, you need a spanner to unscrew the big thin nut and I would add a lot of BP penetrating oil in the process and clean out the threads where the nut is expected to back out. I don't know what new 50 hp engines have. I know on my 90 they now have two screws to undo and she slides right out........one hugh improvement from the early design.

My 2c,

Mark

 

[crem1]

Re: MERC 500 Lower unit TOOLS

It's appreciated to have as much input as possible.
My engine is a 1973 and I do want to take the prop shaft apart for maintenance.
My only other concern, is the spanner good for MERC 500 only or is it interchangeable with other models and years. Anybody have a picture of the spanner?
Thanks

 

[Texasmark]

Re: MERC 500 Lower unit TOOLS

I made my own and that was 30 years ago, so I am just guessing what the OEM wrench looks like, but from a functional standpoint, you (obviously) have a handle on a large, thin, circle (has to fit over the propshaft, so maybe it's not all that thin) with squared off, somewhat thick, fingers (probably about 6) that are bent perpendicular to the circle. It is these fingers that fit into the slots in the bearing carrier nut.

The housing is threaded and you are talking about aluminum that has been painted and been in service for 30 years. Don't expect the nut to unscrew easily. Get a Dremel tool with the wire brush attachment and clean out the threaded groves before attempting to dislodge the nut. A thorough dousing with PB blaster or suitable solvent would help to loosen the corroded interface.

Once the nut is off, the whole assy can be pulled out using the propshaft, and may require a shaft removal hammer...something to grasp the prop shaft/nut with a sliding weight on it that can be slammed to the rear...impact style.

The spanner has to fit the diameter of your gearbox....(3.5" or thereabouts) and several of the midrange engines share that sized housing.

Mark

 

[crem1]

Re: MERC 500 Lower unit TOOLS

Thanks a lot TexasMark, that was extremely useful info