1984 Johnson Javelin 85 hp blows up

[wjhuskey]

Dad's boat motor blew up this week while fishing Toledo Bend in LA/TX. This motor had been rebuilt in recent years and was low houred. Just wanted to ask what could of happened. I know operating a boat and maintaining it properly consists of many do's and don'ts. Motor was a 1984 Johnson Javelin 85 hp. I do know we didn't start using ethanol treatment as soon as some people did but we have been using the treatment for a good while. Just wanted to hear of some reasons good motors like this just randomly blow sometimes. Thanks in advance.

 

[GA_Boater]

It broke. It happens.

Ethanol, treated or not, is not the reason it did whatever it did.

You can't expect a reason when you give no details. So what happened to it?

 

[racerone]

So whay is the model # of this 1984 Javelin 85 HP ??

 

[wjhuskey]

GA boater, sorry for asking what must of been a dumb question. I didn't necessarily say not using ethanol treatment was the reason. I just meant that's one thing we didn't always do that we should have and I know it can damage things over time. I wasn't with Dad on this fishing trip...he's still there and had to buy a new engine. I just know the engine popped loudly while idling out from the dock and it was done for. The local boat mechanic said it wasn't fixable. I don't have the model #.

 

[Tassie 1]

35 yrs old.
as the above answers imply,
it does happen
same as my '81

 

[jimmbo]

The 85 HP Javelin was produced in 1976, 77, and 78. In 1979 and 80 The Javelin was a relabeled 100HP. In 81 the 85 HP and 100 HP engines were dropped and a 90 HP appeared and remained in the line up until the 99.6 inch block was discontinued

As for why it blew up. Carb(s) leaned out, Someone forgot to add the oil, Wrong oil. Piston Ring broke(ticking time bomb on those engines). If previously rebuilt, less than perfect machining and/or poor assembly practices. Poor Break-in

 

[racerone]

This why I asked for model # as I doubt that is a 1984 model.-----Just a crossflow motor and I agree with post #6 here.

 

[wjhuskey]

Thanks for the info jimmbo. Poor rebuild job was a possibility I had mentioned to dad after hearing the news from him on the phone. It was a Craigslist buy and it was listed as a 1984 but apparently the previous owner didn't know for sure. He had gotten it as a package deal with the boat he had bought. It ran great for us for about 6 years. The boat is a restored 1974 Ranger TR-10 and the original Johnson 70 hp blew also. Me and dad has finally learned to just go buy a new engine and be done with it. His new engine is a Mercury 60 hp 4 stroke. Seems like there's not much time to fish for working on boat engines... hopefully this new 4 stroke will be a different story.