Older Mercury 20hp Lower Unit drops .5" but wont come off

[beaug244]

Hey all, I am new to the forum and am in need of a little advice. I have recently got a older, late 70s, 20hp mercury that isnt in the best shape, but fires up and runs fine. I want to change the water pump but cant get the lower unit off. I have been doing a lot of research online and that is how I came across this forum.

I took off the 2 bolts and it dropped about .5". I can put a screwdriver in and wedge it down and it has moves about another .5" before popping back up to the previous position. I figured that if the driveshaft is frozen up in the powerhead it wouldn't be able to drop about an 1". So I figured it to be the shift shaft is frozen or some sort of shift linkage. I have tried quick shifting to get it loose but that didn't help. Are there any bolts to the shift linkage up in the power head or anywhere else that I could be missing?

I would like to try everything before just using brute force to pry it off, as that seems doesn't seem like the best option.

I am fairly mechanically inclined, but this is my first time working on outboards. I would appreciate any advice you can give me. Thanks again for looking.

Edit: Also, the whole bottom unit will move a little, it isn't specifically the front, middle, or back that is stuck.

 

[Arkman]

Re: Older Mercury 20hp Lower Unit drops .5" but wont come off

Mine is a little bit older but I had to take 2 nuts off. On mine there is one sort of behind the drive shaft. There is a little nut hidden up there. Then there were two located right above the propeller. One of those is stuck under a plate you have to remove to get at. Not sure if yours is like that but I can look at my manual when I get home to see what years it covers.

 

[beaug244]

Re: Older Mercury 20hp Lower Unit drops .5" but wont come off

Thanks for the help. Do you mean there is one behind the driveshaft on the lower unit? I am not seeing one at all. Maybe different models...

 

[Arkman]

Re: Older Mercury 20hp Lower Unit drops .5" but wont come off

Yeah. On mine there was a third nut that was right by the driveshaft on the lower unit. Do you know what year or the serial number of your motor. I can try to look it up in my book. Now that I think of it I would guess that you couldn't even drop it .5" if you still had one nut to remove. Like I said, if you have the exact year or serial number i can look it up in my book.

 

[beaug244]

Re: Older Mercury 20hp Lower Unit drops .5" but wont come off

I just got this motor and there is no serial number on there. I have taken it to a mechanic but he wouldnt touch for fear of breaking something. He said that it is in the 70's. I am 99% sure that all of the nuts and bolts are removed. I am thinking its the shift shaft is stuck or some sort of shift linkage.

 

[Arkman]

Re: Older Mercury 20hp Lower Unit drops .5" but wont come off

Well, by all means I am not an expert. I have a 68 merc 20hp and I believe that it is just about the same. If it is the same the drive shaft I have then I cant imagine that would get stuck very easily. The shift shaft is the same thing. All the splines on both align with the way you are pulling off. If you take the top the motor the serial number is stamped on the block somewhere. Check out http://www.eastcoastmarineservice.com/models.html There is a huge list of old motors from them.

I wish I could help more. I know how frustrating it is to sit and wait for an answer. Send me a private message with your email and we can talk more.
Josh

 

[beaug244]

Re: Older Mercury 20hp Lower Unit drops .5" but wont come off

Thanks again for taking your time to help out.

On the side of the motor it has "830-2753" and it says "Super Hurricane". On the front, between the two spark plugs, it says " 1020-2757".

Those don't really link up to anything on the site you gave me or any other site that I have been looking through.

There is a model from the 50's called "super hurricane" but looks nothing like mine and the serial numbers arent anywhere close.

I took some pics that might help identify it better.

 

[beaug244]

Re: Older Mercury 20hp Lower Unit drops .5" but wont come off

is anyone else have any suggestions before i just use brute strength to pry this off?

 

[Arkman]

Re: Older Mercury 20hp Lower Unit drops .5" but wont come off

Check your email. I just sent you something.