Lower unit cavitation plate broke

[southernstyle995]

Went out to test boat the other day an hit a log, now I got a cracked prop an a broken lower unit. What do you guys recommend for this a new lower unit?

 

[DennisG01]

The only thing that we can see in that picture is the broken anti-ventilation plate. Can you show a pic of the prop, as well?

SEI makes decent aftermarket lower units. Mother Yam is, of course, an option. Ebay and other online sources may yield you a good used unit. Check your part numbers - that lower will be used for many different models and that will make finding a used one easier.

You may be able to just swap the internals into a new case, but you'll need to verify that the prop shaft isn't bent using a runout tool.

 

[Doc Stressor]

The problem with swapping the internal parts is that a blown lower unit plus labor can cost more than you would pay for a new SEI unit. Unless you do the job yourself, of course.

I've had several lower units have catastrophic internal failures within 20 hr after bending a SS prop. So SEI is probably the best way to go. For $1000 or so, you get a warranty that is no questions asked. I have a friend who is an inshore guide who rarely gets more than a year out of a lower unit. We have returned units with entire lower half sheared off and he gets a new one every time.

The key thing with SEI lower units is to follow the break-in procedure. Don't run them hard until you have run them at low speed in both forward and reverse. And be sure to change the lubricant according to their schedule.

 

[Fishtales]

The only other option is to take a shot at a used one if you can get it cheap enough. It stinks but Doc likely has the best alternative. That's why the call it BOAT.

 

[Ky Grady]

There is another option and one we have used before.

Look up Skeg Depot, they are in Dallas Tx and they manufacture replacement anti cavitation repair pieces. They do have the Yamaha pieces to fix your problem. You can buy either side that you need. Find you a good welder that can weld aluminum and you're good. Get you some zinc chromate primer and some Yamaha spray paint and paint it back and you should be back in action. Probably need to pull the bearing carrier out so not to worry about heating up the seals. Definitely make sure the prop shaft isn't bent or the gears are ok before investing in the repair.

We used a Mercury repair piece to fix the same issue you have. Turned out nice and didn't have the expense of buying a whole lower unit case.

 

[Rustygaff]

I see no reason why the cavitation plate cannot be welded providing the driveline gets a clean bill of health. Broken skegs are welded back on all the time.

 

[Doc Stressor]

Thanks for the tip about Skeg Depot. While we have a lot of shops around here that do routine skeg repair, I don't know of any that would do an anti-ventilation plate. They say that they would have to fab the part and that would cost a lot of money. Skeg Depot only gets $30 for a pre-machined Yamaha plate. I need to tell some of our local guys about that.

 

[DennisG01]

That's interesting. As I writing my response I wondered "why couldn't it be welded like a skeg". But I had never known of it ever being done. Good to hear.

 

[southernstyle995]

Yea I found a local prop shop that is going to weld it back on for 225. I'll post pics after I get it back. Taking it now.

 

[DennisG01]

Prop shaft?

 

[southernstyle995]

I checked the run out on it an it is good to go!

 

[Ky Grady]

Thanks for the tip about Skeg Depot. While we have a lot of shops around here that do routine skeg repair, I don't know of any that would do an anti-ventilation plate. They say that they would have to fab the part and that would cost a lot of money. Skeg Depot only gets $30 for a pre-machined Yamaha plate. I need to tell some of our local guys about that.

Yeah, we had a customer turn us on to them. The one we got for the Mercury repair worked great.

 

[Jeanette Elaine]

Just FYI- My neighbor had the exact same thing happen and actually looked identical to yours after he hit a log. He called his insurance company and they bought him a whole lower, minus prop of course.

Also I would have a prop guy look at the screw or at least examine it closely, and if you go with the weld job put an indicator on the shaft to make sure it is also straight. If you have twins it might not be as noticeable when running if something is out of whack.
For the weld option it would be nice if you could find the broken piece!

 

[SkunkBoat]

Is that the one that wouldn't come back to neutral?

 

[DennisG01]

Good point about insurance. Often, this type of thing will fall under your comprehensive insurance - like hitting a deer with your car.

 

[southernstyle995]

Is that the one that wouldn't come back to neutral?

No this is the other one. Been having a string of bad luck lately