Update: Engine seized due to hitting a rock (apparently not) - Honda 9.9 - 2010

[biederboat]

See update on 4th reply down. I picked up a great deal on a Honda 9.9 XLS high thrust outboard. Low hours, but the prop hit a rock and it looks like it somehow seized the block (threw a rod or something). For the price I got it (about what a lower unit goes for on eBay), no worries if it's not really repairable. I am going to tear into it shortly but just wondering if someone knows what I should expect. The previous owner took out the lower unit but the power head was still seized. I'm thinking that the connecting rods are kind of the weak link but is there something I should do or try before I tear it apart?

Thanks,
BB

 

[Scott Danforth]

if its in the power head, you will need to carefully pull everything apart, inspect everything, and hope its something minor. to put back together, you will need to hone the bores, new rings, new gaskets, etc.

personally I would find a running $100 motor

 

[Grub54891]

As Scott said. Tear it down, and use it as a teaching tool. If it's repairable, fine, if not, you learned how they work.

 

[Sea Rider]

Strange that hitting a rock will seize a powerhead. Pull powerhead out and check if possible to crank, if possible powerhead is OK, must be a lower leg isue.

Happy Boating

 

[biederboat]

So I took everything apart, lower unit is fine. Drained oil and very small amount of water (tablespoon at most, entirely separate from the oil which looked okay) drained out. Pulled the head and it's obvious the combustion chamber had water in it which had frozen the rings to the cylinder walls but I can't tell if this was the catastrophic failure. Block, head and head gasket look good. My theory is that the motor sucked in water and seized at low rpm (the guy was trolling or holding steady in what was likely ocean swells on the outside of a jetty) so it likely didn't break anything. I did have to take the rod end caps off and tap on the connecting rods to get the pistons out so I could pull the crank out. At this point, the main damage would appear to be the rings, possibly the cylinder walls (but they feel pretty good actually) and the connecting rods from tapping on them.

Any other theories as to how water would have entered the combustion chamber? Can this motor suck water in without a complete submerge (i.e. a wave spills over the top or it takes a quick dunk due to a swell coming into the transom. I'm thinking that if this happened the water eventually evaporated out of the chamber but some would have leaked past the pistons into the crank case.

I did a repair on a similar situation, 90 HP Force that had the cylinder cover gasket leak (bought it frozen from corrosion). I replaced the gasket, tapped the pistons out, used steel wool to clean the rings and walls and it ran "good" (for a Force, anyway). Used it until the lower unit crapped out.

Thanks,
BB

 

[Sea Rider]

Is that a 2 or 4 strokes OB ? 2 Strokes OB's have carb located at extreme of cylinder head compared to 4 strokes that have carb located sideways of power head, could eventually swallow more water entering from rear cowl. Personally would install a new set of standard piston rings and discard the old ones.

Happy Boating

 

[pvanv]

Is that a 2 or 4 strokes OB ? 2 Strokes OB's have carb located at extreme of cylinder head compared to 4 strokes that have carb located sideways of power head, could eventually swallow more water entering from rear cowl. Personally would install a new set of standard piston rings and discard the old ones.

Happy Boating

All Hondas of modern years are 4-strokes.

 

[Sea Rider]

Ok, assume will collect more water entering from rear cowl having a side carb....?

Happy Boating

 

[biederboat]

Sorry for late response, I'm not getting reply feeds even though I'm subscribed and my email address is correct. I did examine the head gasket more closely and can see where water possibly entered into once cylinder but not the other. Overall, I'm not too concerned as I won't have that much money into a "short rebuild". Will have about $100 in parts, maybe 10-15 hours labor and I will do a thorough inspection.

BB

 

[Sea Rider]

When head gaskets becomes hardened with use, was not correctly retorqued after break in period ended, water will enter combustion chamber and OB will miss, the more throttle applied the more OB will miss. Retorque to specs new head gasket after first 10 worked hours, will find that was torqued to will not remain same...

Happy Boating