Re: [OMC-Boats] OMC HYDRO-ELECTRIC LOWER UNITS

Yep - that's what is going on. Talked to another boat parts
yesterday who also knew alot about these shifters. The "extra"
shifter I bought on ebay a couple years ago as a spare for times like
this was in fact for an OUTBOARD OMC engine setup. The outboard
shifters have a switch in them that looks identical to the
strerndrive switches BUT they only send power when in forward and
neutral. Not in forward and reverse as needed for sterndrives. $
%&$##*@...!! So now I have a broken plastic 5 wire switch and a wrong
3 wire spare. Might have a source for a correct 3 wire though.
More on that later.

So yeah, part numbers would have been good to verify here, however
it's important to note the outboard switch has NO part numbers on it
anywhere and the same is probably true for the sterndrive versions of
these switches. Yes the parts manual shows two different numbers,
but they don't seem to be marked on the switches anywhere. Also
important to note the shifter I bought on ebay, although it's for an
outboard OMC, looks just like the sterndrive version. And the part
numbers for it are stamped on the inside - so not much chance of being
able to verify anyway. So the moral to this part of the story is
if you are planning to buy a spare shifter off ebay, make sure the
guy selling it KNOWS for sure it came from a stern drive not an
outboard otherwise it's useless to you.

Jeff D

On Aug 24, 2009, at 7:39 PM, Lee Shuster wrote:

>
> OMC introduced a new lower unit in 1968 on it's then-new 55-hp 3-cyl
> outboard. In 1969, they used a larger version gear case on the V-4
> outboards. Eventually (1978) these units were adapted to OMC
> Stringer I/O's.
> There are no-doubt members of this list running these "Hydro
> Electric Shift" OMC outboards and I don't want to exclued them from
> our recent on-going discussions.
>
> Someone suggested borrowing the remote controls from these later
> outboards and using them for a parts source. That may be possible, I
> just haven't tried it.
> Without studying an OMC wiring diagram, I wouldn't want to say for
> sure. And the mechanical switch design is most likely, still prone
> to failure.
>
> I do know the OMC engineers' control "logic" took a major "C-change"
> and I thought the background theory would be worth sharing.
>
> For some reason, OMC engineers decide to incorporate a fail-safe,
> "locked-in-forward" approach in the event of electrical or hydraulic
> failure.
> In other words, FORWARD GEAR, NOT NEUTRAL became the default gear
> position, and you'd always get home safely?
> And no more wind-milling props on the back of fast moving trailers.
>
> The shifting setup of the lower unit is what OMC called their "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 hydraulic oil pump that supplies various
> pressure on a spring loaded shifter dog. Makes you appreciate the
> "KISS? simplicity of our pure electric shift design.
>
> The wires leading to the lower unit (at the powerhead) are still
> "Green" and "Blue". But now, the engine must be running or cranking
> over in order to shift OUT OF FORWARD GEAR.
>
> With Hydro Electric Shift units,
>
> In neutral, your remote controller supplies 12v to the "Green" wire.
> In reverse, your remote controller supplies 12v to both wires, the
> "Green" one and the "Blue" one.
> In forward, the remote controller supplies no voltage to either
> wire. (And the spring-loaded shifter dog forces the unit into
> forward gear.)
>
> To check the lower unit for proper shifting AND to make sure you
> have no trouble there, remove the spark plugs to avoid problems and
> to allow a higher cranking speed with lower compression.
>
> This next step eliminates the actual remote control shifter switch,
> in case problems may exist there....and allows you to focus on
> checking the lower unit operation.
>
> 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. You
> may crank the engine with the key switch or by energizing the
> starter solenoid with a jumper wire).
>
> With no voltage applied, the unit should be in "locked-in" forward.
> No need for a ground jumper... the lower unit's already grounded.
>
> Lee
>
>
>
>
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Received on Wednesday, 26 August 2009