OMC shift interrupt switch / lower shift cable

[General Lee I]

I have a 1991 OMC Cobra 4.3L with the typical shifting issues. When I purchased the boat ealier this year the shift interrupt switch tab was bent out of the way, after alot of research I figured out what the switch was for and straightened it. When I shift into gear with the engine running on muffs, the "Y" plate will not return to release the switch, in both forward and reverse. I'm thinking the lower shift cable is worn but i'm not positive, does the boat need to be in the water for this to work properly. How easy should the lower shift cable move? When I unhook it from the linkage it will move but with some force, I have to take the cable with both fist to shift manually, should it shift back and forth easy with two fingers?

 

[a70eliminator]

Re: OMC shift interrupt switch / lower shift cable

The lever with the notches that activate the switch needs to move freely on its pivot, it should easily spring return on its own, the pivot is a lubrication point that needs maintained.

 

[bruceb58]

Re: OMC shift interrupt switch / lower shift cable

Sounds like the shift cable needs to be replaced.

With the boat out of the water, the ESA should never engage. With it in the water, it should only engage coming out of gear because of the load that the prop puts on the dog gear.

If it is engaging at any other time, the shift cable itself is providing friction that shouldn't be there.

Besides a failed shift cable, if the boat is used in salt water, the area around the bellcrank at the drive can get full of salt deposits that could cause some extra friction. Since you should be pulling your drive anyway every year, now is a good time to pull it and see what that area looks like.

 

[General Lee I]

Re: OMC shift interrupt switch / lower shift cable

I did make sure the "Y" plate pivot and all other linkage was well lubed and free. Still had the problem.
The boat has never been in salt water to my knowledge, but i will remove the drive to inspect the bellcrank area. When you say "pulling your drive" do you mean the lower unit only or the upper and lower unit as an assembly?

 

[bruceb58]

Re: OMC shift interrupt switch / lower shift cable

Then the bellcrank area won't likely be a problem. When you pull the drive, you do it as an assmbly.

Sure sounds like you need to replace your lower shift cable.

You should buy a factory OMC manual before you do any work.

 

[General Lee I]

Re: OMC shift interrupt switch / lower shift cable

Thanks for the advise.

I do have a manual on order, waiting for the manual to start the repair.

Is there any other maintenance that you would recommend doing to the outdrive while its off.

Thanks
Ben

 

[john744]

Re: OMC shift interrupt switch / lower shift cable

Hello General.......... Required reading for all OMC Cobra Owners is Stuart Hastings OMC Cobra web page. Although I agree you should obtain a service and parts manual, I found this to clear up a lot of misconceptions surrounding Cobra shifting problems. Do yourself a favor - it's free!

Good Luck


http://www.hastings.org/~stuart/cobra/

 

[bruceb58]

Re: OMC shift interrupt switch / lower shift cable

Is there any other maintenance that you would recommend doing to the outdrive while its off.

1) Inspect and grease U-joints.
2) Inspect and grease gimbal bearing
3) Inspect u-joint bellows. If 5 years or older replace it.
4) Align engine with gimbal bearing. You will need to buy a tool for this. Around $50 on ebay. Very important that you do this.
4) Buy gasket set for replacing drive.
5) Drain gear oil and replace(do this with the drive on). Make sure you follow proper filling procedure which is crtical for a Cobra. Drive is filled from middle hole...not bottom. Make sure you replace gaskets/o-rings on all plugs removed.

 

[General Lee I]

Re: OMC shift interrupt switch / lower shift cable

Does the gimbal bearing need to be aligned only when replaced or everytime the drive is removed?

Will the marine grease that I use for my trailer work for greasing the u-joints and gimbal bearing?

Thanks a million!

Ben

 

[bruceb58]

Re: OMC shift interrupt switch / lower shift cable

Everytime the drive is removed. The stringers can settle so that is why you want to check annually. It has nothing to do with removing the drive...just that you have to remove the drive to do the check.