Outboard motor question for those in the know.

Ed L.

Ed L.

Well-known member
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I have a boat with an Evinrude 48hp with a broken Hyd assist. I have located a Johnson 40 hp with a power tilt and trim that needs a lower unit. I'm thinking should I put the 48hp lower unit on the 40hp with the power tilt and trim or will I be losing much performance doing that and would it be better to put the power tilt and trim on the 48hp. Any thoughts?

Thanks,

Ed L.
 
The big question is will the 48 lower unit fit on the 40?
If so, that will be the easier fix since it is pretty darn easy to change lower units.
Undo about 6 botls, loosen the shaft & shift linkage, drop old LU off, put on new gskets, impeller, etc.., and slap it back together.
Its almost that easy.
 
They need to be the same series of motor and same shaft length.

An easy way to search and do a parts comparison is to use boats.net parts finder system. Open up two windows and find each motor by year and HP,then do a part cross reference on say the lower unit case or drive shaft. Once each part is shown in a separate window you can look at the bottom of each screen and see what other motors the part fits. For a Johnny/Rude there should be dozens listed. Actually you should only have to open up one window and see the cross referenced motors at the bottom of the screen.

For the majority of the 1990's era Johnny/Rudes in the 40 to 55 HP motors the only component difference are the carberators. Nearly all other parts are the same parts from the gasket sets to the block and pistons. This means that you will not be loosing any performance from the 48 lower unit to the 40HP motor since they are the same lower unit. Its the carbs and how the govenor system is adjusted that makes it a 48HP motor. Its probably a detuned 50HP that has had the govenor linkage adjusted to take out some top end.

If you need the extra 8HP then take the trim and tilt and install that on the 48HP motor. You will have to make sure the wire harness plugs fit and they can be a pain to get to down below the other parts like the VOR system.

The other option is to buy a new assist system from these folks. It would depend on the cost of the 40HP motor.

http://www.spidermarine.com/
 
Ray & Carl,

Checked the BRP website and the numbers all match for the 40 and 48. Going to do a compression check and determine which power head is in better shape and go from there.

Ray,

I had wondered about the detuning and carb thing. I just talked to a mechanic that said basiclly the same thing you did with a little bit more techno babble.


Thanks,

Ed L.
 
Ed,

You can always keep the other powerhead for a spare. Swapping the lower unit is the simple task and it can always go back on the 48 powerhead down the road if needed (provided you keep it around).
 
Dave,

You bet! Have you priced a starter lately....WOW!....

It was a good buy too. I paid less for the motor than buying a salvage T&T!

Take care,

Ed
 
Ed,
check both lower units for a straight prop shaft. A common problem on outboards that have touched the bottom with the prop and causes many problems with the internals of the lower unit inc. seals and bearings.
 
I've got a 48 on my flats boats.

It was explained to me when I purchased it back in '97 that the 48 is actually a 50hp that came standard with "tilt/trim."

So, the 48 is actually 50hp.
 
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