OMC Cobra Grinding Into Reverse

[PAUL HEENAN]

Hi All, long time viewer/first-time poster....

I have a 1990 Four Winns Candia 200 5.8 Ford with an OMC Cobra outdrive. I bought it about a year ago and have learned a ton reading through the forums so thanks for that. I am a car mechanic by education/trade so the engine basics i have a good handle on. Learning the outdrive and associated mechanics has been a steep learning curve. I had a local boat shop (OMC master tech worked on it) do a few things to the boat while it was in storage due to wear/preventative maintenance. Specifically, the u-joints, both bellows, gimbal bearing and shift cable. The gimbal bearing was making noise and now that is gone. I also had/have an issue where the outdrive will grind going into reverse and is worse when it is cold/engine speed is higher. The new shift cable helped with that issue but didnt resolve it completely. I have read extensively about the ESA system and will do some checking of that when i am next with the boat this weekend. I have checked the system by pressing the switch at idle (not in gear) and the engine does stumble but does not die. That said, i noticed that only SOMEtimes it will do that while on the water. Having read a couple forums and watched extensive videos on ESA and cable adjustments, i am starting to think my cable from the remote control/shifter is either binding or poorly adjusted and not adequately moving the shift cable to the outdrive when i go into reverse. I have changed the outdrive oil twice now since i have owned it and checked for any metal or other indicators of gears failing and have found none so i am assuming/hoping its an adjustment issue. If there is anything else you have seen or would suggest i check given the issues i am having, i would welcome them. Thanks in advance for your help!

 

[Lou C]

If it grinds going into one gear and not the other you may not be getting equal travel in both gear positions. This is dependent on both the transom shift cable adjustment and the remote cable adjustment. Both must be right to get equal travel on either side of neutral. The ESA system has nothing to do with this problem; the ESA only is activated when shifting from in gear to neutral with a load on the prop (ie in the water).

 

[PAUL HEENAN]

Hi Lou C, thanks for your reply....I am going to go over the remote cable extensively this weekend and do some checks on the freshly installed transom shift cable. Maybe i am misunderstanding the ESA system but everything i can find seems to indicate that the system reduces idle speed by interrupting the ignition signal when going into AND out of gear....reverse, mainly, from what i have read. The idea being minimizing damage to the dog clutch as you engage reverse gear and easing the shift from forward or reverse gear to neutral under load as you said.

 

[Scott Danforth]

if youre shifting out of water, grinding is normal as you dont have the load of the water on it.

if you are trying to ease it into gear, stop......shift with authority

 

[Lou C]

Agreed you have to shift fast but if either cable drags it will slow down the shift and it will grind but also if you don’t have enough throw in one of the shift directions it will
also grind. About the ESA, while the original manuals make some reference to it engaging while shifting into and out of gear that I believe that is an error. The way it works is related to how dog clutches work. They are designed to grab and not let go when there is a load on the prop. When out of the water no load on the prop so it will shift in and out easily with no ESA needed. But when there is a load on the prop (water) it will go into gear easily (with a solid THUNK, not a grriind-clunk); but for shifting out of gear in the water the clutch dogs will resist coming out of gear, this puts pressure on the cable jacket which moves the load lever on the engine shift bracket. This in turn triggers the interrupt switch which lowers the idle from 600 to approx 450 rpm and that reduction in torque applied to the prop shaft allows it to drop out of gear. Mercruiser has a similar system but less sophisticated in that there is no module to lower the idle speed; it momentarily grounds the ignition but if the cable is sticky it can stall the engine.

So on an OMC Cobra it should not engage the ESA shifting into gear at any time, and only when shifting OUT of gear in the water with a load on the prop. If the ESA engages when shifting into gear something is wrong with the cable, linkage or shifter assembly in the lower unit there should not be resistance to going into gear, only coming out of gear with a load on the prop. The ESA is 100% triggered by load on the shift cable jacket.

 

[PAUL HEENAN]

Thanks guys.....everything i am doing is with the boat in the water with load on the prop....i take both your points about shifting fast and not babying it but i believe Lou is correct.....even when i shift fast into reverse resisting the temptation to "ease" it into gear and therefore limit the gear noise it still does it.....it seems like i am on the right track with the mention of unequal travel of the various cables between forward and reverse.....forward consistently does the right thing and just clunks into gear with no grind.....reverse has always been funny, especially when cold and it gets better as it warms up but never officially goes away.....when i am with the boat later this week i am going to check the travel. I would guess it is simple as measuring the cable travel engine off when shifting from neutral to forward and neutral to reverse and comparing the measurements (as a starting point)? Also, given the age of the boat, is it worth taking the remote control/shifter apart to have a look inside and see if anything needs to be lubricated/cleaned/etc.? Last question, i noticed the other day that the allen head set screw at the bottom of the shifter where it attaches to the shifter assembly is missing and am now starting to wonder if that is causing me issues.

Again, thanks for your help and apologies in advance if these questions are dumb.....new to this!