1972 Evinrude Outboard

[adwjr]

I may have an engine for this project of mine. Its a 1972 Evinrude 125 hp. I've been told these engines can have problems but there is also a fix for them. What are the opinions here?


I hope everyone has a very Merry Christmas?

[tashasdaddy]

they have hydro electric lower units, that parts are not available. controllers, solenoids. just to start.

[emdsapmgr]

I ran a 72 100 hp engine for four years and enjoyed every minute. Great running engine. Never had a problem. The powerhead is early crossflow, but the basic design spanned 28 years, a testament to the OMC engineers. The 125 was the high horsepower model which had excellent heads and large carbs. If it has good compression, it should provide good service with regular maintenance. This was the last year of the hydro-electric shifting lower units as Tas mentioned. This lower unit is not specifically problematic, but if you do have problems with them, few mechanics have worked on them and many of the electrical shifting parts are NLA. I doubt you can adapt a later year mechanical shifting lower to it, since the block is not setup for the belcrank shift mechanism. I'd make sure your control box properly shifts the lower through F-N-R properly before putting a lot of $ into your project. Ebay frequently has parts for these older engines, including entire engines sold for parts.

[tashasdaddy]

if the lower unit shifts, and the control switch is bad, we do have a way of making a switch for it. just ask. here is excellent info on the lower unit.

Hydro Electric Shift)
(J. Reeves)

The shifting setup of the lower unit is what's called a "Hydro Electric Shift", which is quite complex consisting of voltage being applied to solenoids in the lower unit which in turn change oil passages via a oil pump that supplies various pressure on a spring loaded shifter dog. The wires leading to the lower unit (at the powerhead) are "Green" and "Blue". The engine must be running or cranking over in order to shift out of forward gear.

You CAN NOT use HI VIS lube in that lower unit. You MUST USE what OMC calls "Premium Blend" lube, commonly called "Type C". (A thinner lube)

In neutral, you need 12v to the "Green" wire.
In reverse, you need 12v to both wires, the "Green" one and the "Blue" one.
In forward, there should be no voltage to either wire. (The spring loaded shifter dog forces the unit into forward gear)

To check the lower unit for proper shifting to make sure you have no trouble there, remove the spark plugs to avoid problems and to allow a higher cranking speed.

This next step eliminates the actual shift switch in case problems may exist there.... Disconnect the blue & green wires at the knife connectors (the rubber insulated boots) leading to the lower unit at the powerhead, then using jumpers, take voltage direct from the starter solenoid to apply voltage to the "Green" wire for neutral, then both wires 'Green" & "Blue" for reverse (Remember the engine must be cranking over in order to shift).
With no voltage applied, the unit should be in forward. No need for a ground jumper... the lower unit's already grounded. You may crank the engine with the key switch or by energizing the starter solenoid with a jumper wire.