1971 9.5 HP Johnson Connecting Rod Failure

[FJK]

Part of top piston connecting rod and cap blasted through the cast aluminum crankcase housing after motoring at WOT for about 20 minutes. I am considering installing rebuilt or new power head if cost is not prohibitive. But maybe this failure is a symptom of some other problem that will trash the replaced power head too. Carburator was recently rebuilt by Authorized OMC Service Center. They replaced fuel hose to tank which I locate near bow. Parts do not look oil starved. Have not disassembled engine yet. What do I look for to identify the cause of this failure? Any suggestions would be appreciated.

 

[F_R]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

Has anybody had it apart? Failure to torque the rod cap screws to specs, failure to use new lockplates on the screws, mismatched parts, all come to mind. Hammering (knocking) from worn out wrist pins could do it. Water intrusion will destroy the bearings. Just plain rotton luck is a possibility too.

 

[FJK]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

I bought engine new. Power head has never been apart. Have never had WOT problems, knocking, etc.

 

[WillyBWright]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

Nothing lasts forever. Let's face it, the thing is 36 years old. Let it rest in peace. Move on. Part it out. This is the 21st century. Has been for a few years now.

 

[CATransplant]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

Nothing lasts forever. Let's face it, the thing is 36 years old. Let it rest in peace. Move on. Part it out. This is the 21st century. Has been for a few years now.

Nothing wrong with 36-year-old motors, in general. There's obviously something wrong with his, though.

Seriously, I just saw a 9.5 of the same vintage in my local Craigslist for $300. Guy said it ran like new. It would be silly to fix one, when you can buy a replacement for that kind of money...if you're hooked on that particular outboard. Then strip the busted one down for its useful parts and your set for 36 more years of happy boating.

 

[FJK]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

Thank you for the reply. Although my broken motor looks mint compared with what I've seen at boat/marine stores for $400 (same vintage), the cost of parts to rebuild, if available, would probably make the project impractical. Your suggestion of looking at the used market probably makes more sense although I need to educate myself on how to buy used. Also, it seems to me I have heard of the existence of a used outboard price guide similar to the NADA book for cars. If true, it would be a good place to start don't you think? I will watch Craigslist.

 

[iwombat]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

I lucked out with mine and found a complete replacement powerhead sitting on a shop shelf for 30 years. Ended up getting it for around $250. If you take your time and be patient you never know what you're going to find.

 

[FJK]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

I lucked out with mine and found a complete replacement powerhead sitting on a shop shelf for 30 years. Ended up getting it for around $250. If you take your time and be patient you never know what you're going to find.

The guy at Seaway Marine ( in Seattle, I think ) thought he had one on the shelf and would sell it cheap (?) just to get rid of it. Brand new! When he went to look it was gone. I'll bet you got it. Congratulations and thanks.

 

[iwombat]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

You're looking at it a few posts above. That's what happens when the parts manager is in your bagpipe band. We were originally looking for a set of cases so I could save myself the hassle of rebore/oversize and found the complete powerhead just sitting there.

I do see powerheads for that motor on ebay from time-to time. I also see lots of complete motors on craigslist from $50-$350 depending on condition and expediency of sale.

 

[iwombat]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

Come to think of it, i do have a set of cases from a parts motor I could send you. They're a little rough, and need a small repair in the exhaust chamber, but they're very repairable and yours for the cost of shipping if you want 'em.

 

[Fl_Richard]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

iwombat -

Thats what these forums are all about. As an un-intrested party thats a very nice offer.

Thank you for re-storing my faith in humanity!

 

[iwombat]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

Hey, I'm just tired of tripping over the box it's sitting in.

 

[Fl_Richard]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

Damn!

 

[FJK]

Re: 1971 9.5 HP Johnson Connecting Rod Failure

Come to think of it, i do have a set of cases from a parts motor I could send you. They're a little rough, and need a small repair in the exhaust chamber, but they're very repairable and yours for the cost of shipping if you want 'em.

Thank you for the kind offer. I don't know which direction to take yet but I'll let you know.