02 Yamaha 250 ox66 corrosion hole on engine

[Pursuit2550]

Like the title says. I was doing some maint. to my engine oil tank and I decided to take it off and clean it. Anyways I take it off and i go and clean it. When I get back to install it this is what I found. Now about the engine. When I bought it it had 189 hrs. It shows from the out side, everything is almost like it just came out of the factory. When I bought it (used) I did the regular maint., changed water pump,filters,t-stats, etc. Now when I took off the t-stats I noticed corrosion where it sits. I dug into it and it poked a hole into the inside cavity of the engine. No problem I grinded it out and put JB Weld. Today I saw this the exact same thing as the t-stat housing, only on the outside. I also took out the t-stats and the JB Weld is holding just fine. Only thing is that there is still noticeable salt and corrosion where the t-stat sit. Now I flush my engine evertime I get back from boating, so why is there this salt and corrosion in there. Why did it corrode like that on the side of the engine? I already did the same JB Weld job on it, but I am afraid the engine is corroded inside. What do you guys think? I think the guy that had the engine before never flushed it.

 

[Pursuit2550]

Re: 02 Yamaha 250 ox66 corrosion hole on engine

Any ideas!

 

[robert graham]

Re: 02 Yamaha 250 ox66 corrosion hole on engine

Looks like some corrosion concentrated in certain areas. How do your sacrificial zinc anodes look, and are they attached/grounded good and tight? Guess the JB Weld can buy you some time with this motor, but maybe there's other holes in places you can't see and could be critical to motor performance? Maybe previous owner used motor in saltwater and failed to flush it out after use? Good Luck!

 

[Pursuit2550]

Re: 02 Yamaha 250 ox66 corrosion hole on engine

I checked all the anodes and all are fine, I thought they would have been eaten up but no they weren't. Everything else looks good.

 

[robert graham]

Re: 02 Yamaha 250 ox66 corrosion hole on engine

Well that hole has to make you wonder what's going on inside the motor, but maybe it was just a flaw in the aluminum casting and the salt/water attacked it there. You could spend the time and money to pull the heads off for an inspection, try to clean/remove/JB Weld bad spots, or you can just run the motor until it dies(maybe sooner, maybe later), but it's gonna worry you 30 miles out on the water. Maybe have your local Yamaha dealer look at it just for his opinion, but a rebuilt powerhead could run you $3000, maybe a good used freshwater motor? Good Luck!

 

[zbail]

Re: 02 Yamaha 250 ox66 corrosion hole on engine

I did a Google search and did find 2001 ox66 block issues. I wonder if there is a TSB or recall from Yamaha. If there is, it will be top secret for their liability purposes. You may want to make random calls to different coastal dealer service departments around the country and see if they can let you in on that secret. You may be able to contact the factory rep for some help.
Almost looks like it had a pocket that corroded from a bad casting. I always knew that older Yamaha's had corrosion problems, but thought they improved since the mid 90's.