76' OMC 235 Sterndrive, No Forward - No Reverse

[zag123]

I managed to lose my ability to shift my 76' OMC 235 sterndrive into forward yesterday. Shortly thereafter, I lost the ability to shift into reverse. First of all, I was pulling the kids on the tube and all was well. We paused and decided to run up to the damn. Once there, I dropped the tube back into the water, and then it happened. I started her up, and she engaged into forward and while throttling up, she slipped out. I tried this again and she slipped out. It wasn't a bad hub on the prop. This was definitely from the sterndrive unit itself. So I tried reverse. All was good. So, we loaded back up and I attempted to reverse back to the ramp, very slowly. Until... we got swamped by a passer-by killing the motor. Once I got her fired back up, I tried to engage reverse, and there was nothing. No clicks, no nothing. My thoughts, as I know the drive is electric, could there be corroded terminals in the shifter? Since everything failed at the same time that is. Would I lose forward and reverse nearly simultaneously for some other reason. How do I trouble shoot this problem. What type of cost should I plan for? Did I miss something? I did notice that pulling to button (not sure of the name) on the shifter that is never operated properly. She would start regardless of the buttons position and regardless of whether she was in gear or not. That's why I was thinking electrical in the shifter. Any input would be greatly appreciated!

 

[Howard Sterndrive]

Re: 76' OMC 235 Sterndrive, No Forward - No Reverse

start by checking with a voltmeter at the wires inside the transom area going down to the drive - fwd wire is green and reverse is blue - you'll slide a little rubbery sleeve back from the knife connectors to expose the metal connectors.
engage fwd with ignition on and see if there is 12V (compared to a good ground or batt neg terminal) at the green wire, same check for reverse on the blue wire.
Check as well that the drive bonding wire is attached as the drive housing is the return path for current (i.e. "ground")
If there is power to those connectors, and drive is well bonded to intermediate housing, your problem is not likely electrical, it's a problem in the outdrive.

If no power there, work your way back to the helm shifter checking for voltage- the switch inside is a common failure point.

If the issue is in the drive, and if the water pump impeller hasn't been serviced lately, one of the first suspects is the w/p shaft splines. (a related symptom would be engine overheating after loss of propulsion)
other drive possibilities:
water in lower unit combined with old insulation causing stray current when trying to engage direction coils
broken part in upper
broken part in lower

 

[zag123]

Re: 76' OMC 235 Sterndrive, No Forward - No Reverse

start by checking with a voltmeter - you'll slide a little rubbery sleeve back from the knife connectors to expose the metal connectors. Check as well that the drive bonding wire is attached as the drive housing is the return path for current (i.e. "ground")

Howard Sterndrive; where would I find these wire harnesses. Also, I see that a few posts refer to solenoids on top of the motor. Is there a solenoid that could be the issue? I've ordered a manual, though plan to initiate troubleshooting prior to receiving the shipped book. Must I access to the wires from inside the sterndrive itself or would I see these harnesses elsewhere? Thank you.

 

[Redrig]

Re: 76' OMC 235 Sterndrive, No Forward - No Reverse

The shift wires he is referring to are on the port side of the intermediate, in the bilge area. go on the back of the boat and look for the black cable that is going from the sterndrive through the intermediate, that is what you are looking for but on the engine compartment side.

the sileniods on top of the engine control the tilt, nothing to do with shifting.

 

[southkogs]

Re: 76' OMC 235 Sterndrive, No Forward - No Reverse

A manual at the bottom of THIS thread you can download. NW Redneck has a bunch of good information in that entire thread.

 

[zag123]

Re: 76' OMC 235 Sterndrive, No Forward - No Reverse

So I downloaded the manual. Thanks Southkogs! I am running through the wiring now. There is a "Purple" wire, "Green", "Blue" and two "White" wires in the harness, at the helm shifter. I know that "Purple" is 12v power when the key is on. I know that "Green" is FWD, and "Blue" should be RVS. What are the two "White" wires for? Are they both ground wires, one each for FWD and RVS? I didn't want to be missing anything. I would have assumed that each FWD and RVS coils were grounded to the sterndrive itself.

Also, any thoughts on water being the cause of grounding out the coils in the sterndrive? I plan to tap open the unit and checking for water, while changing out the fluid. For some reason, no one stocks Type C fluid around here...

 

[Howard Sterndrive]

Re: 76' OMC 235 Sterndrive, No Forward - No Reverse

my guess on the white wires would be neutral safety switch...so you can only engage starter in N