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1984 Evinrude 15 hp lower unit

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spinomc

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Hello, I have seen posts addressing 9.9 and heavy high horsepower motors but not much on the Evinrude 15hp question I have.

I currently have a 1984 Evinrude 15 hp short shaft with lower compression than I like but have a chance to get a very nice 1974 Evinrude 15 hp with a long shaft.

Will a 1984 Evinrude 15hp complete lower unit fit and operate correctly on a 1974 model? This would of course make the 1974 model a short shaft which is what I need anyway. They appear compatible but feel more comfortable asking this forum for input. Thank you for reading.
 
Fact.----A 74 unit will " fit " on a 2007 model. -----Not the same internally but fits.------Simply remove the 5" extension housing.----Perhaps cut 5" off water tube if the 74 was factory long.
 
Welcome to The forum. That's right. You can switch the driveshaft from housing to housing without taking them apart. In other words there is no nut on the pinion, preventing you from pulling the shaft out. Remember when you install the impeller, that it turns clockwise looking from the top of the motor so when you install the impeller in the housing it will look like it's turning to the left from the bottom. When you handle that water supply tube make sure that you don't wiggle it too much because it can damage the grommet which seals as it goes into the powerhead up above. This can be a problem and lead to plugging off the water flow so after you've shortened the tube and cleaned any burrs off the tip, make sure that you can still blow air through there. Lubricate the splines on top with a high quality grease or anti-seize, where the drive shaft goes into the crankshaft. Use a little anti-seize on all housing bolts..... Including the water pump bolts.
 
Thank you for the replies. Forgot about that water tube. I'll be sure to keep that in mind. I will post photos when I work on it. Haven't figured out the free time yet. Perhaps showing my progress will also help another poster with a similar task. Thanks again.
 
Yes...these are fantastic motors...lots of them still out there and in service. Make sure the fuel pump isn't leaking past the main diaphragm and into one cylinder. This will cause rough and over rich idle.....fairly common problem.....this is on all the OMC's that use the little compact square fuel pump.
 
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