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DAMMIT!! I bent my prop shaft and chewed up my prop 1980 Johnson 25 hp J25RCSA

Jhanratt

Regular Contributor
DAMMIT!! I bent my prop shaft and chewed up my prop on my 1980 Johnson 20 hp J25RCSA
I hit a gravel bar HARD while tubing with my kids the other day. It lifted the motor pretty much right out of the water and stopped the boat. The prop had pretty good chunk out of it and it picked up a nasty vibration. I limped it home and saw that the prop nut was cracked and a substantial piece of the prop was missing. Tonight I pulled the prop to look for a part number and pitch. I spun the prop shaft and observed that it is clearly bent.

ARGHH!!!

I just did a gear case re-seal last year on this outboard followed by a head gasket.
It is a salty old cuss but it runs like a top and has never let me down in about 20 years.
The prop shaft is discontinued.

Did I just sign it's death warrant or is there a way that I could straighten the shaft?
I am pretty handy with a wrench but I don't own a dial micrometer, lathe or similar equipment.

I don't really want to spend much on it because it really is a nasty salty old cuss but it does run strong!

Any advice.

Thanks

Jeff
 
You must have whacked that thing mighty hard. Sorry 'bout the bad luck. J25RCSA is a 25hp, not 20. Which is a good thing because it uses the old two-piece gearcase. Which is a good thing because they made that old design for about 100 years (well maybe not quite). I would think you should be able to find a used shaft without too much trouble.
 
Do you know someone with a bearing press? I would try and straighten the shaft if you cannot find a good used one. There are alot of good used gearboxes out there.
 
If it makes a difference it is a 20 horsepower. The J25RCSA is a model number from the gear case diagram I used to order the seals when I re-sealed the gearcase. It is a two piece gear case with about six screws holding the bottom on. The exhaust comes from a port after the prop not through the prop.
I made low ball offer on a 1980 parts motor last night. That might work out and is only a little more than the price of a new prop.

I will probably tear it down and see if I can straighten it anyway.
Would a drill press have enough pressure to bend? If not I am sure I can find a press somewhere.

What horsepower and year range can I buy a parts motor and have compatible gear case parts?

Thanks
 
I have straightened them with a splitting maul and some strategically placed pieces of oak. Maybe use a hydraulic jack and do the same I am sure McGuyver could figure it out:) Just dont damage the sealing and bearing surfaces. Any good machine shop could straighten it depending how/where its bent.
 
If it makes a difference it is a 20 horsepower. The J25RCSA is a model number from the gear case diagram I used to order the seals when I re-sealed the gearcase. It is a two piece gear case with about six screws holding the bottom on. The exhaust comes from a port after the prop not through the prop.
I made low ball offer on a 1980 parts motor last night. That might work out and is only a little more than the price of a new prop.

I will probably tear it down and see if I can straighten it anyway.


Would a drill press have enough pressure to bend? If not I am sure I can find a press somewhere.

What horsepower and year range can I buy a parts motor and have compatible gear case parts?

Thanks

While the basic gearcase was used for many years, the splined shaft and propeller came out in more recent years. I'll let you do the research on that. Check parts lists here at marineengne
 
A friend of mine is a machinist, I had him try to straighten our the crankshaft from an Arctic Cat side x side (how it got bent is a long story). He used a dial gauge and a 20 ton hydraulic press. He almost had it straightened and made one more tweek to try and get it perfect. The crank cracked in 2. Ended up buying a second hand crank. Moral of the story.......if you aim for perfection, you may end up back at square one. In any case, nothing to lose! Good luck.
 
I dropped off the prop shaft at a machine shop I know well. They said it will most likely break. They pointed out that not only does it have a wobble but the spines show that it also has a twist. I will post either way. I am trying to locate a used or inexpensive prop and or prop shaft now.

The parts diagram calls for:
prop shaft # 323294
prop 9.25X7 # 389067
prop 9X9 # 389068
prop 9X10 # 389069
prop 9X12 # 389944


My prop is labelled 9X10 # 315084. If i understand right the first number is the diameter and the second number is the pitch. I don't understand why my prop is not a match unless it was replaced with a super-ceded part number?
Will i regret it if I change the size or pitch? Right now it idles down very well for trolling, gets out of the hole reasonably well has a top speed of about 32 km/hr and can tow a kid on a tube with a reasonably light spotter. Overall it's a pretty good set up.

Thanks

Jeff
 
You can call seaway marine in lynnwood WA just be ready to bend over if they have one new. Have the model number ready weekdays only pacific time. If you can get up on a plane pulling a tube stick with that pitch prop for sure.
 
From what I can find that design was from late 70s-early 90s 14-28hp motors. There are a couple complete gearboxes on ebay maybe you can talk the guy down on the price or keep an eye on craigslist for a parts motor. If you can find a propshaft new I doubt it would be less than $250.00
 
Update

The machine shop was successful. I just picked up my straightened propeller shaft and I am about to put it back together.
Unfortunately I was too slow on the new in the box prop which was pointed out to me by kimcrwbr1. (Thank you for everything!!). I was waiting to see it I could come to terms with a local guy on a parts motor and I missed it.

So I have two questions:

1.) would you run this prop until a new one can be sourced?
IMG_3119.jpgIMG_3120.jpg

2.) Would it make a huge difference in performance to go from my prop 9X10 part number 315084 to a 9X12 389944 I have found a good used one for $40. I am not super keen on changing anything because the boat idles down well to troll, has decent holeshot, pulls kid on a tube and tops out at 32km/hr. The parts manual I have for my motor does list this prop as a replacement prop for my motor. The seller says it will add top end speed but I don't know.

Thank you all for your sage advice!
 
Last edited:
1 - No, I would not. Take it to a prop repair shop. Most any marine place would know where to go/send it. It'll come back looking like new.

2- I can't answer that one.
 
For 40 bucks run it for now until you determine if it will work you can always keep it for a spare! Do not go by speed use engine rpm at WOT. It may be fine for a light boat and you can use the prop with less pitch for water sports?
 
Sorry I never did reply a final answer on this one. The shaft was straightened at my friends machine shop.
I had the prop rebuilt at a local shop. The boat runs like a champ and has ever since I put it back together.
Thanks for the help!
 
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