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Need advice bad lower unit on 1985 mercury 75HP

R

redfisher_85

New member
I need a little help. I have an 85' Mercury 75 HP ELPT w/a bad lower unit. I am looking for a used one and I found a guy who has one that may work with my motor. Here is what I know about my motor: its a 1985 Mercury 75 HP ELPT 4 cylinder, the serial # is 0A116481, the part # is 1075625 and the motor itself is black and orange. I dont know much about the other guys motor except for the fact that it is an 85 HP Mercury and looks to be a mid 80's model. He told me the serial # is 3870489 but I tried to research it w/no luck so Im not sure if that # is correct. Also his motor is blue and black. My first question is does anyone know if the serial # he gave me is legit, if not any clue on how to find out what the correct # is? Also can anyone tell me a little more about this guys motor? And lastly does anyone know if my lower unit and his lower unit is interchangable? And answers or advice would be appreciated. Thanks. And sorry about the novel I just wrote.
 
What is the problem with the lower unit you have? If you buy a used lower, you don't know what condition or how long it will last.
 
popdude said:
What is the problem with the lower unit you have? If you buy a used lower, you don't know what condition or how long it will last.
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Not sure, the motor makes a clicking sound only when the boat is rolling not when the motor is idling. I'm thinking maybe a tooth or something is broken off on one of the gears. Or something along those lines.
 
Not sure what you mean. When the boat is in the water and you are in forward gear it makes a clicking noise? How about reverse? Does the noise increase with speed? Highly unlikely a single tooth is broken. Please try to be specific.
 
popdude said:
Not sure what you mean. When the boat is in the water and you are in forward gear it makes a clicking noise? How about reverse? Does the noise increase with speed? Highly unlikely a single tooth is broken. Please try to be specific.
Click to expand...

Yes in forward gear it makes a clicking noice even when your out of the water and you spin the prop it clicks. And reverse doesn't work.
 
My friend, someone has removed the lower unit and did not re-install it correctly. That clicking should be heard when the boat is out of the water and in forward gear and you spin the prop by hand. That is without the motor running. There is nothing wrong with the lower unit. The lower unit must be removed and re-installed correctly.
 
popdude said:
My friend, someone has removed the lower unit and did not re-install it correctly. That clicking should be heard when the boat is out of the water and in forward gear and you spin the prop by hand. That is without the motor running. There is nothing wrong with the lower unit. The lower unit must be removed and re-installed correctly.
Click to expand...

Ok but i have been fishing out of the boat for two years and it has never done this before. It has just started making the clicking noise in the past couple of months
 
So you have owned the boat for two years and never had reverse? I really couldn't say why the clicking has manifested lately but this is classic lower unit not installed correctly. Possibly the previous owner replaced the water impeller and did not install correctly and possibly thought he broke the lower unit and decided to sell. The other possibility is the shift shaft got stripped or bent or has just worn to the point where the noise has manifested. Just check it out. What do you have to loose? By the way, change that water impeller while you have the lower unit off. Should be done every two years anyway. If you don't replace that on a regular basis you run the risk of overheating.
 
Hey buddy I really appreciate the advice and I'll go ahead and pull it off and check out the shaft and gears etc. and I had planned on changing the impeller no telling when the last time it was changed. Thanks again.
 
popdude said:
So you have owned the boat for two years and never had reverse? I really couldn't say why the clicking has manifested lately but this is classic lower unit not installed correctly. Possibly the previous owner replaced the water impeller and did not install correctly and possibly thought he broke the lower unit and decided to sell. The other possibility is the shift shaft got stripped or bent or has just worn to the point where the noise has manifested. Just check it out. What do you have to loose? By the way, change that water impeller while you have the lower unit off. Should be done every two years anyway. If you don't replace that on a regular basis you run the risk of overheating.
Click to expand...

Sorry for digging up an old thread here, but I'm having a similar issue with the clicking sound and getting my prop to engage. The boat has never had any drive issues in the 6 six years I've owned it. I hit a log this past weekend, which destroyed one one of the prop blades. I was trying to limp the boat back to the boat ramp(quite a ways), and all of a sudden it slipped out of gear and wouldn't go in to forward or reverse. With the boat out of water, the prop now clicks when spun by hand that I never noticed before.

I have the lower unit off now, and I'm working on removing the prop shaft from the housing to inspect further.

Any ideas?

Thanks in advance.

Jon
 
It should be obvious once you get the prop shaft out.

Jeff

PS: Might have a good propshaft in my shed if you need it.
 
fastjeff said:
It should be obvious once you get the prop shaft out.

Jeff

PS: Might have a good propshaft in my shed if you need it.
Click to expand...


I'm able to get the lower unit into gear properly by manually turning the shift rod on the lower unit. Upon reassembly, the shift lever would only engage properly once before slipping again and creating the same "in between" gear issue. Any ideas?

I'm gonna look into the linkage, but was also thinking the shift rod could be damaged.

Jon
 
Could be the two shafts were not lined up correctly.


Take all of the slack out of the lower shifter shaft BEFORE putting the LU back up. Put both in forward (the LU can jump into F if you use N).

Jeff
 
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