Yamaha 15hp outboard mounting screws ceased

[Zingaro69]

I have a Yamaha 15 horsepower outboard. The mounting screws to attach the outboard to the transom of my dingy have been getting harder and harder to turn. I've tried in the past wd40 and coating the screws with Lana coat but after returning to the boat having been in storage on the hard and storing the outboard below decks and out of the weather the mounting screws are seized and I can't seem to free them.

Does anyone else have this problem with their Yanmar outboards? Any idea what I can do to free it? And can they be drilled out and replaced? How do I keep this from happening in the future?

S/V Thin Wolf

[Sailorman Ed]

I had the same problem with a 5 hp Honda. So I applied Tefzel frequently and then run it in and out several times. You have to get the lubricant inside the female threads.

[JPA Cate]

We use marine grease on our Yamaha's mounting screws, turns fine.

If you can find a solvent that you can introduce, it may loosen up your lanacote enough to turn them, then clean and oil or a light grease will probably work for you. Otherwise, heat, and a longer lever and try to turn them. The little plastic handles for turning them are fragile after UV exposure.

Ann

[a64pilot]

Heat as in heat gun not torch, PB Blaster, or a mix of automatic transmission fluid and acetone.

[marlinmike]

I agree with a64pilot, PB Blaser is really good stuff, once freed up some marine grease.

[Cheechako]

Yes, I've had that issue with the 15 HP Yamaha 2 stroke for sure. I found grease to not work, Lanocote worked marginally. Not sure why they are so bad. The key ended up being to do it often.... and be sure to coat the part of the thread that sits inside the housing!
I've wondered if silicone grease would work....

[Zingaro69]

So it isn't completely ceased I've gotten about a quarter turn on each but can't get much past that. With great difficulty I can turn it forward and back that quarter turn. I've access to a torch but not a heat gun. The engine hasn't had any gasoline in it for 2 years. Torch okay?

S/V Thin Wolf

[Terra Nova]

Use AeroKroil to free up the seized threads.

[Cheechako]

I'd be very careful with the torch... doesn't take much heat to destroy the strength of aluminum.... so just be careful..

[Zingaro69]

Thanks for all the advice. I was able to free them up with a small butane micro torch. Slathered them with plenty of marine grease and they are running smooth again.

S/V Thin Wolf