Yamaha Plug for Lower Unit is hard to get in and out

I Am Mello

Cadet
Joined
Dec 10, 2010
Messages
23
I have a 115 Yamaha 2 stroke 2004. I just bought it on an 18 ft Blue Wave.
The motor has 137 hours on it and you can tell its in very good shape.

I was doing some service work on it before I put it in the water and when I was changing the lower unit oil the BOTTOM screw was so tight I almost couldnt get it out.

When I put it back in I kept thinking I had it cross threaded, but I know that it wasnt. I know this because the screw seems to be perfectly square when it bottoms out in the hole. The thing is so hard to get on and off that I scared I might break it in the lower unit. (I have a Mercury that is very easy to get on and off)

Has anyone had this problem or have any ideas what might be the problem?

Thanks for any suggestions,
I Am Mello
 

Bluefish

Petty Officer 2nd Class
Joined
Mar 14, 2001
Messages
125
Re: Yamaha Plug for Lower Unit is hard to get in and out

Try getting a new plug and see how it fits and if you have to run a tap in remember to install a new oring/washer each time.
 

I Am Mello

Cadet
Joined
Dec 10, 2010
Messages
23
Re: Yamaha Plug for Lower Unit is hard to get in and out

Humm Bluefish good deal. I will do that. I was thinking about the hardness of the metals in both the screw and the female part of the housing. I wonder which is the hardest. I can remember years ago designers thought about things like this. The would make the screw out of a much softer metal than the housing. That way if you strip something it would always be the 5 dollar screw and not the 1500 dollar housing. I wonder if designers still think this way?:rolleyes:
 

triumphrick

Lieutenant Commander
Joined
Jun 26, 2008
Messages
1,737
Re: Yamaha Plug for Lower Unit is hard to get in and out

The screws in my F115's are stainless..except for the magnet on the tip of the lower screw. I wonder if the magnet tip on yours has caused the screw some problems? And what happens when you move the top screw to the bottom hole?
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: Yamaha Plug for Lower Unit is hard to get in and out

The lower drain plug is stainless steel with a magnet and the lower case is just aluminum, it really shouldn't be that hard to unscrew that drain plug. The threads on the drain plug should be easy to inspect, while the threads in the lower unit may be not so easy to inspect. Maybe buy a good tap(not cheap Harbor Freight junk), the same threads as the drain plug and carefully with your hands clean and straighten those threads on the lower unit by screwing the tap in and out gently until the threads are clean and clear. Maybe the previous owner put some type of glue or sealant on those threads to prevent leakage or loosening of the drain plug? Just take it slow and easy on the threads. Good Luck!
 
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