Uh-Oh! Hit a stump! '78 25 Johnson

Chip P · Jul 14, 2007

Tried out my 25 hp Johnson yesterday and in the process found a stump. It kept running but wouldn't go in gear. Killed it immediately and trolled back. It was pumping water when I was trying it out but didn't look to see if it was pumping waterafter I hit the stump. Got to the bank and loaded it. I could put it in gear and turn the prop, I don't know if I should be able to do that or not. No exterior damage at all. Wasn't in WOT at the time either. Any suggestions on what I should check for before taking it in for repairs? I can stab a lower unit if I need to take it apart. Thanks for any info!

iwombat · Jul 14, 2007

Re: Uh-Oh! Hit a stump! '78 25 Johnson

Shear pin sheared or prop hub spun is the most likely thing that happened. If that's the case you can put it in gear, but the prop will just turn on the shaft.

bben76 · Jul 14, 2007

Re: Uh-Oh! Hit a stump! '78 25 Johnson

don't know a lot about it but i hit ground in a low rev situation last summer with my '71 60hp. bent the prop, had it replaced and haven't had any issues since, seemed to be tougher than i thought. i've heard some discussion about some type of safety built into some props where there is a rubber casing inside that prop that separates/breaks during a prop strike to protect transferring the strike to the shaft.

hopefully someone can clarify what that looks like and feels like. could be that it is going into gear it's just not spinning the prop because that safety piece has broke.

Chip P · Jul 14, 2007

Re: Uh-Oh! Hit a stump! '78 25 Johnson

Just got home and put motor in water and it does not pump water. I guess someting happened to the upper part of the drive shaft. The only way to check it is to pull the lower unit right and look at the top of it?

CATransplant · Jul 14, 2007

Re: Uh-Oh! Hit a stump! '78 25 Johnson

Not a good sign. Yes, pull the lower unit and begin inspecting.

Chip P · Jul 14, 2007

Re: Uh-Oh! Hit a stump! '78 25 Johnson

Broken drive shaft, any suggestions on how to get the broke off piece out? It broke off at the upper spline.

BoatBuoy · Jul 15, 2007

Re: Uh-Oh! Hit a stump! '78 25 Johnson

If you can't tickle it out with a long probe, you'll have to remove the powerhead. There's a driveshaft on ebay that may replace the one you broke - don't know for sure. Ebay number 260139679601.

CATransplant · Jul 15, 2007

Re: Uh-Oh! Hit a stump! '78 25 Johnson

Chip P said:
Broken drive shaft, any suggestions on how to get the broke off piece out? It broke off at the upper spline.

Oh! Bad news. Try a long parts retrieval magnet...several times. That might do it.

You can always pull the powerhead, as well.

I'm glad all my ancient outboards have shear pins. They're a lot easier to change.

F_R · Jul 15, 2007

Re: Uh-Oh! Hit a stump! '78 25 Johnson

The o-ring may still be up in the end of the crankshaft. See if you can snare it with a piece of wire. The stub should then just fall out. Try starting the motor, it may rattle out. Otherwise, it's pull the powerhead time.

There is another thing that will cause breakage there: A bent gearcase or exhaust housing. Could just be a coincidence that it just now broke with a little help from the stump. You can't diagnose the bent parts except to take it apart and check the parts on a surface plate and dial indicator. If something is bent, it will eventually just break another shaft.

Chip P · Jul 15, 2007

Re: Uh-Oh! Hit a stump! '78 25 Johnson

Thanks for the replies, I tried cranking it, poking it, tapping the top of the crankshaft, and will try a magnet tommorrow.

krceynar · Jul 16, 2007

Re: Uh-Oh! Hit a stump! '78 25 Johnson

How old is your outboard? I may have a shear pin that broke. This is kind of their function - to save your lower unit. If you remove the prop - is should be right behind it.

Uh-Oh! Hit a stump! '78 25 Johnson

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