Broke piston rod Honda BF 2.3

[quatin]

I had a mishap recently where I dunked this outboard in fresh water while running. After draining for a while, it started right up. Did consecutive oil changes, ran for a couple hours and everything seemed fine. Today all of a sudden, clank, ping and motor siezed.

Took the head cover off and found pieces of metal everywhere and the piston rod sheared. Is this worth fixing? What are my next steps?

I do love this little motor, but having it blow up on me mid ride has shaken my confidence. If it's not repairable, I would like to buy another, but only if I can rule out bad design as the cause.

 

[fredrussell]

They’re a VERY reliable little engine. Like all small petrol outboards they’re prone to jets blocking but not con rods snapping. I suspect that had something to do with the dunking though it does sound like you did all the right things post dunk.

 

[DownWest]

Sounds like you had a hydraulic lock with water in the combustion chamber. The strain on the rod likely cracked it. Might be fixable? The crank could have been damaged too.
I had a seizure in a car engine. It was rebuilt with the crank reground. Several thousand miles later, the crank bust...

 

[vyv_cox]

Sounds like you had a hydraulic lock with water in the combustion chamber. The strain on the rod likely cracked it. Might be fixable? The crank could have been damaged too.
I had a seizure in a car engine. It was rebuilt with the crank reground. Several thousand miles later, the crank bust...

This is a very common mode of failure. It can be difficult for a regrind to create the necessary radius between the journal and the web. A right angled interface is a stress-raiser that often results in fatigue. I worked on exactly this problem at a refinery following several failures of rebuilt pumps.

 

[Boathook]

Engine running and having water enter it seems to break most engines. I suspect that the cost of spares won't be cheap and then there is that nagging feeling of what will break next, especially after bits having been floating around inside.

I would buy another if you like it and keep the old one as spares, especially the carb.

 

[DownWest]

This is a very common mode of failure. It can be difficult for a regrind to create the necessary radius between the journal and the web. A right angled interface is a stress-raiser that often results in fatigue. I worked on exactly this problem at a refinery following several failures of rebuilt pumps.

I had a chat with the machinist on this point. He also said that he thought the crank might have a slight twist, so it was likely stressed even though I feathered it when I felt it slowing down.

 

[quatin]

Engine running and having water enter it seems to break most engines. I suspect that the cost of spares won't be cheap and then there is that nagging feeling of what will break next, especially after bits having been floating around inside.

I would buy another if you like it and keep the old one as spares, especially the carb.

That's unfortunate, but expected. Are these engines sold separately somewhere? Seems easy to just swap a new one on there if available.

 

[rotrax]

I had a mishap recently where I dunked this outboard in fresh water while running. After draining for a while, it started right up. Did consecutive oil changes, ran for a couple hours and everything seemed fine. Today all of a sudden, clank, ping and motor siezed.

Took the head cover off and found pieces of metal everywhere and the piston rod sheared. Is this worth fixing? What are my next steps?

I do love this little motor, but having it blow up on me mid ride has shaken my confidence. If it's not repairable, I would like to buy another, but only if I can rule out bad design as the cause.
View attachment 180952

That my friend needs the "Fling Test".

Flinging into a skip.

Its Donald Ducked.

I suspect it hydraulic locked and bent the rod which then failed, wrecking the engine.

 

[DownWest]

I will add to this that I dunked a Seagull Century plus getting off a the beach in Bray harbour, Alderney, some time ago. After a very windy (gale) night in the race. I was dropping off px. Wind was on the beach so getting off was tricky. I dropped the clutch a bit quickly with a few revs on in our 8ft ply tender. That put the stern under and stopped the engine.
Nothing loth, I furiously rowed off then did a 'ferry glide' to get back to our moored boat. My father gave me a huge ticking off for trying that, as if I had missed, it would have been out of the harbour in quite rough conditions.

Bit later, he acknowledged that it was well done...

Quick flush out with the Seagull and back in action, bit cruder and tougher than a Honda.. Things have moved on from then ('63)

 

[Boater Sam]

Claim it on insurance and scrap it. Engines that have had a hydraulic lockup are seldom right ever again.
If it locked up it is almost certain that the rod bent. The huge forces involved will have distorted the crank and maybe even the engine block bearing areas.

 

[Steve65]

Yes repairable 100%
Go on ebay and buy yourself a Honda gxv50 con rod.....Approx £10 The crank will be fine..possibly will have bent the push rods. Just straighten them, they are very soft.
Its done about £12 worth of damage!!!

 

[Steve65]

If you cant find a gxv 50 con rod, a gxh50 con rod is identical.
When you fit it you dont need to add the metal oil throw onto the big end casting. Your Honda already has an oil throw inbuilt

 

[quatin]

Yes repairable 100%
Go on ebay and buy yourself a Honda gxv50 con rod.....Approx £10 The crank will be fine..possibly will have bent the push rods. Just straighten them, they are very soft.
Its done about £12 worth of damage!!!

Do you know if I can I just buy a GXV50 motor and swap it out?

 

[Steve65]

Do you know if I can I just buy a GXV50 motor and swap it out?

No.you cant.

 

[Snowgoose-1]

If the OP goes for Steve's option , it would be great for a report back. Over a 20 year period mine has been dunked twice . Fortunately without the engine running. Still going strong, but sounds like a bag of nails rattling.

 

[Steve65]

If the OP goes for Steve's option , it would be great for a report back. Over a 20 year period mine has been dunked twice . Fortunately without the engine running. Still going strong, but sounds like a bag of nails rattling.

I would be happy to report back...I have rebuilt literally hundreds using these rods without a single problem

 

[quatin]

I would be happy to report back...I have rebuilt literally hundreds using these rods without a single problem

Whats the typical reason you see broken piston rods? Anything else that should be replaced & inspected while I'm at it? The piston feels seized in the cylinder and so does the motor itself after removing the 3 bottom bolts.

Sucks there's not a drop in motor replacement. I'd feel more confident in the motor just replacing all of it, but I'm willing to spend a little time & money rebuilding. Keep it as a backup motor if I can get it running again.

 

[Steve65]

These con rods only usually break from a hydrostatic lock ( overboard when running )
Or running without oil.
The piston will not be seized in the block...the block and liner is alloy.
Buying a new replacement powerhead will cost nearly as much as new engine.
If you buy a used block I would recommend you see it running.
Normally day to day running you dont particularly see much wear with these motors.

 

[DownWest]

Just re-read the OP,
No mention of draining the oil and flushing?
Local friend dunked his Merc 3,5 4T in seawater. We got it back to the house the next day, a Saturday Though it had not been running when dunked
there was quite a lot of water in the crank case. Normally one would get the local agent to strip it PDQ, but it was a Saturday. So I stripped it and cleaned it out carefully. The Ins agreed that waiting until Monday would have ruined it. Yours was fresh water, but?

 

[quatin]

These con rods only usually break from a hydrostatic lock ( overboard when running )
Or running without oil.
The piston will not be seized in the block...the block and liner is alloy.
Buying a new replacement powerhead will cost nearly as much as new engine.
If you buy a used block I would recommend you see it running.
Normally day to day running you dont particularly see much wear with these motors.

Damage more extensive upon further dissassembly. Piston missing a chunk, but more worringly the block is missing a chunk next to yellow pipe. Thoughts?