1972 OMC 120hp Goes forward in reverse gear and reverse in forward

[vanvalis]

Hello.

A few months ago I purchased a 1972 Bellboy with an OMC 120hp 4 cyl.

I did a basic tune, up, replaced the tilt solenoids, fixed up the tilt clutch and that's about it. Ran great on land at home wit the water hooked up.

I took it out on the lake and it fired right up. However when I put it in forward gear it goes in reverse. In reverse it goes forward. I have no idea if the old owner (cannot get ahold of him) drove it like this or not.

The only other symptom is that when I accellerate the outdrive pulls the stearing wheel to one side.

Any ideas?

Thanks,

Van

 

[GMC2003]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

Are the knife connectors hooked up to the right at the back of the engine?

 

[NW Redneck]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

You definitely have your wires crossed somewhere! I'm mot familiar with that particular control, but try taking the side plate off and see if you can see the connections for the shift wires. They may be stake-on type connections and you can just switch them there. If not check the knife connections at the back and swap them there.

Edit: I found these pages in my manual that may help:

 

[southkogs]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

I've got the same controller as you ... don't crack that mug open just yet. Check the knife connections at the back of the engine going to the stern drive first (those are your shift wires, and likely they're just backwards - it's easy to do).

That controller has a toggle switch in it that energizes (F or R) to the sterndrive. If it's that thing, there's supposedly no saving one and they are a booger to find from what I hear too. It's kind of a pain to put back together if it "springs" apart when you open it.

 

[vanvalis]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

thanks guys this is great great information. on my way home from work now to check it out. a related question, the guy at the marina thought this was not an electric shift outdrive. could this be the case or are all omcs of this year electric shift?

 

[southkogs]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

You're an electric shift. The controller is electric shift too. All of the early Stringers were electric shift. They made 'em that way up through about '77 when the hydro-mechanical and mechanical shift took over.

You've even got the same "hey, let's put another hole in the boat" steering rig that I do

 

[vanvalis]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

You're an electric shift. The controller is electric shift too. All of the early Stringers were electric shift. They made 'em that way up through about '77 when the hydro-mechanical and mechanical shift took over.

You've even got the same "hey, let's put another hole in the boat" steering rig that I do

Well shoot, I shouldn't have listened to the guy. I put hi vis in the lower gear case on his suggestion. I ran it on the lake for about 10 minutes driving around in my reverse/forward fun times.

Do you think I damaged it? I guess I will just pump it out and put the right stuff in there. Sound right?

I really enjoyed working on this thing believe it or not.

Thanks again.

-Van

 

[vanvalis]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

Thank you sir. What manual is that from? I think I need to buy that one.

-Van

 

[southkogs]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

Well shoot, I shouldn't have listened to the guy. I put hi vis in the lower gear case on his suggestion. I ran it on the lake for about 10 minutes driving around in my reverse/forward fun times.

Do you think I damaged it? I guess I will just pump it out and put the right stuff in there. Sound right?

I really enjoyed working on this thing believe it or not.

Thanks again.

-Van

Actually - just for kicks, try putting the type C in the lower and see if that solves your shifting problem. I'm still thinking your wires are crossed, but the oil can have funny effects on the lower if you use the wrong stuff.

I don't think you hurt anything in that first run out, though.

 

[southkogs]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

Thank you sir. What manual is that from? I think I need to buy that one.

-Van

... since I already stole NWRedneck's photo, how 'bout a rip off his link too? Actually - this one is Don's. Click the top link.

 

[vanvalis]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

Actually - just for kicks, try putting the type C in the lower and see if that solves your shifting problem. I'm still thinking your wires are crossed, but the oil can have funny effects on the lower if you use the wrong stuff.

I don't think you hurt anything in that first run out, though.

Well cool. I read on another post a guy put hi-vis in the lower and was getting a pull to the side at least. Not sure about the forward/reverse. Will pick some up on way home from work tomorrow and give it a shot. Then if still going backwards will check wires.

Thanks again.

 

[NW Redneck]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

The pics I posted are pages are from an OMC factory manual . Best $$ you can spend if you're going do do most of your own work. Way better than the Seloc or other aftermarket ones. Also you can look for my thread in the OMC forum titled 'Stringer info', I posted some stuff from my original owners guide that gives lube types/amounts, plug types, timing settings and other general info that may come in handy.

Having the wrong oil can cause shifting problems like not going into gear or popping out of gear, but I haven't heard of anyone having forward and reverse changing. Could be possible though I guess. Only use either Premium Blend or 'type-c' oil in the lower. Hi-vis or any other good gear oil is fine in the upper. Having the hi-vis in there for a while won't have damaged anything though.

 

[vanvalis]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

Update:

I finally got into the engine. It looks like I did have those connectors swapped backwards (the green/blue colors were faded). Also I drained the lower unit and replaced it with type C. It was late so I didn't start it up and validate everything yet. Will try that tonight or this weekend. Thanks again!

 

[GMC2003]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

You may have to adjust the exhaust rudder to get it to stop pulling to one side...

 

[vanvalis]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

Another update:

Took her out on the lake. It was the knife connectors. Seems to be working fine. Might be a bit of a pull to the side left in there though not as bad. please let me know about this exhaust rudder you mentioned. I didn't know it was adjustable.

So a new issue discovered, I can only get it up to about 15 miles per hour at full throttle running about 3000 rmp. Is there some kind of limiter on there? How fast does your 120hp omc go at full throttle? Just for reference I have an 18 foot bellboy.

I just found this post by the Oracle of the Sea - regarding how to trouble shoot the system "Engine Won't Reach Operating RPM. Check" so I am going to go through those procedures today.


Thanks again, you guys rock.

Van

 

[NW Redneck]

Re: 1972 OMC 120hp Goes forward in reverse gear and reverse in forward

WOT for that engine should be 4000-4400 rpm. There is no limiter. Follow through the steps in that thread and let us know if you need any assistance. The 'exhaust rudder' GMC mentioned is called the rudder trim tab and it is the hollow part right above the prop, part #3 in the pic below:

Loosen the bolt and adjust the position of the tab left or right. From the book: "If less steering effort is required in a port turn, move the tab slightly to port. If less steering effort is required in a starboard turn, move the tab slightly to starboard."