boat motor won't go forward but will in reverse

[mclark4642]

hey guys,

I asked this question about a month ago, so I apologize for starting a new thread, but I thought I'd ask it again, in a "cleaner" method.

This is a 1972 Johnson 85hp outboard motor.

I took my boat out about 6 weeks ago, and everything seemed to be working fine. I stopped and fished for a while, but when I started it back up and moved the shift gear into forward, the motor reved up but would not go forward. Suspecting I was stuck on a stump or something, I put the gear into reverse and backed up about 15 feet, and then put it in forward again, and it still wouldn't go forward! When I got the boat back home, I put the water muffs on and ran it in forward and reverse, and the propeller seems to turn just fine.

On the previous post, someone suggested that I might have "spun the hub". I took the propeller off and looked at the rubber hub on the prop and everything seemed to feel tight and snug on there. I also checked to see if there might have been any tangled line or anything, but I didn't see any.

Does anyone have any suggestions on what else I might need to look at, or could this be a bigger, more expensive problem?

Thanks!

 

[jbjennings]

Re: boat motor won't go forward but will in reverse

Myself, I'd scribe a mark across the hub and see if it was turning. Tashasdaddy has a nifty pic of how to do this. Ask him if he'll show it to you if he already hasn't. You CANNOT tell if a prop hub is spun by feeling of it. You can only tell when you put the power of the motor to it. Trust me! However, I'd think unless it was really spun badly, it would idle in forward but would begin to slip when you applied a little throttle.

Also, your shift cables or shifter itself may be out of adjustment.

The last, and most expensive scenario would be a totally ruined clutch dog and likely forward gear.

Question: What kind of shifter does your motor have? Is it that push-button shift? That could be the problem, but I know absolutely nothing about them so I can't tell you how to fix it if it is.

Good luck,
JBJ

 

[tashasdaddy]

Re: boat motor won't go forward but will in reverse

#1 you have a hydro-electric shift motor. it automatically defaults to forward, when the electric signal is not sent to the lower unit. you either have a major problem, or a spun prop. draw the line across the prop. put the boat in the water and put it into forward, if the prop is spun the lines will not be in line. if the line is still complete, you have other problems.

for info: 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.

 

[mclark4642]

Re: boat motor won't go forward but will in reverse

hey guys,

I appreciate the quick feedback. I assume I would just draw a line as you have indicated in red in your picture, correct? Also, would the boat have to actually be in the water when testing this, or would putting water muffs on be sufficient to test the spun prop theory? What would be the best thing to use in order to make the line that wouldn't wash off?

Thanks again,
Matt

 

[TommyA]

Re: boat motor won't go forward but will in reverse

Sharpie markers are waterproof but even a china marker wouldn't wash off very fast. I believe you would need the motor in the water to offer resistance to the prop thus showing if it is simple spinning on the shaft.

 

[mclark4642]

Re: boat motor won't go forward but will in reverse

okay! I'll give it a try this weekend and let you guys know. I hope that's the problem since I'm sure the other would be a lot more expensive and I'd have to take it in since I'm not too good working with motors. Thanks again!

 

[ezeke]

Re: boat motor won't go forward but will in reverse

Use the cotter pin as a pointer and scribe the line or use a Sharpie.

 

[F_R]

Re: boat motor won't go forward but will in reverse

using ezekes method, you don't have to remove the prop.

 

[Vintage66]

I do a lot of work on vintage boats between buying, restoring and flipping, and repairs as they come in. I'm still learning, but this is a topic that I've seen first hand more than once and even had happen to me. Each time I have seen a boat come in that suddenly lost forward gear, it wasn't the prop. If the prop hub goes, it will slip either way but usually you'll be able to idle along. This reeks of clutch dog/forward gear issues. I hate to say it, but that's always been the case around here.