91 OMC Cobra Shift question

[tw8572]

Hello All!

This is my first post here, but let me say a quick thank you for the countless questions that have been answered by the experts in this forum for me over the last year or so!

Onto my issue: 91 Four Winns 190 Freedom with a 4.3 OMC Cobra. When first purchased boat it shifted relatively smoothly, but always idled very low and stumbled quite a bit, especially when cold. When taking the boat to have some work done on an unrelated issue, the mechanic said that this boat was idling way too low and that the ESA wasnt working. He changed the ESA out, dialed in the carb, sped up the idle, and off we went. (Presumably, the previous owner didnt understand the ESA and just adjusted the idle down to where the boat barely ran) The boat now stumbles when coming out of gear as I understand it should and shifts from F or R back to Neutral very smoothly. Going into gear from Neutral into either gear there is no grinding, and not much force is needed, but there is more of thud there was previously. I wouldnt go so far as to say that it "bangs" into gear, but there is definitely more of a "thud" then before.

So finally onto my question and I'm sorry if this has been covered before - when searching this I got some conflicting information. On my boat, should the ESA come into play when going from N into gear? As far as I can tell mine does not. And second, I realize it's tough to accurately assess my "thud" over the internet, but does this seem normal for this drive?

Thanks in advance!!
Tom

 

[projo198]

Re: 91 OMC Cobra Shift question

I look forward to hearing the responses because I have been wondering the same thing. I set my idle VERY low, but my motor runs pretty smooth so there isn't an issue.

The book says you are supposed to shift "briskly" into gear, and I have read that there should be a thud. Not sure how much of one though. Mine isn't bad.

What is your idle, in gear, in the water? In gear?

 

[tw8572]

Re: 91 OMC Cobra Shift question

What is your idle, in gear, in the water? In gear?

Using the dash tach - which isn't the greatest I realize - it floats between 500-700 when warm. Which should be right in the ballpark according to the manual.

 

[projo198]

Re: 91 OMC Cobra Shift question

I would suggest a handheld tach if you cna get your hands on one. Connecting to the neg terminal on the ignition coil and grounding will give you your tach.

The ESA is to help you shift OUT of gear into neutral, not really for going into gear.

Mine currently idles at 550. It shifts well, starts up 1st time and never stumbles. I set it low to ease shifting once I got the motor running good. If your engine can handle it I would suggest a lower idle if you are worried about it.

 

[Reinell-BRXL-191]

Re: 91 OMC Cobra Shift question

The drive should have a slight tickity noise when going from neutral to gear, as it reaches that gear there should be a slight connection noise letting you know the gears are engaged.. some call this a "thud" I call it a thunk.. learn where you shifter travels from neutral to in gear.. then you shift to that point briskly, then once you hear the connection, you are good for acceleration... With the dog clutches, it's not a good idea to go further than the connection point (gear engagement) from neutral, reving the engine before the gears engage will shorten the life of the clutch dogs and gears

The ESA should only come in to play when shifting from a moving gear to neutral as long as the prop is being turned by the forward or reverse movement of water over the prop.. Say you are kicking along at a few knots, and decide to shift out of gear, the forward motion of the boat will cause torque to be created on the gears in the outdrive from water pushing the prop.. this makes it hard for the clutch dogs to let go... so, the ESA senses this torque and transfers it to the ESA, the ESA stumbles the engine, which releases the torque on the moving parts, and allows the gears to dis-engage. So, unless you are in the water and moving, the ESA shouldn't be doing much... your RPMs at idle in the water should be in the 550-600 range.. and the idle should be smooth

 

[bruceb58]

Re: 91 OMC Cobra Shift question

Basically, if the prop has a load on it,the clutch dogs will have a force on them which makes them want to stay engaged because of the angle of their teeth. In that case, the ESA should operate and stumble the engine helping the teeth disengage.