OMC COBRA 5.8 EFI and ESA

[Lou C]

Sounds like you tried to cover all the bases...
questions...
did you check the drag of the shift cable with it disconnected at both ends with a fish scale? should be not more than 2.5 lbs, the drag on the cable is pretty important...
also if you shifted the lower unit when it's off the boat, with someone turning the prop shaft or the driveshaft, does it shift relatively easily from N to F and from N to R?
Is the shifter bellcrank in pivot housing moving easily, these can get crudded up by deposits from water getting past that gasket...
Stiffness can be the control, control remote cable, transom shift cable, the shifter bellcrank in the pivot housing, or inside the lower unit. Since you just had yours re-done, that's probably not it.
Based on what you're saying about what you tried, it does sound like it could be the control unit. My original OMC one shifts very easily, almost too easily, the neutral detent is not that positive.
the water in the gear oil could have been the seal in the water pump adapter, TC has a video that shows how to change that, they also sell a modified part with an extra seal in addition to the standard one, I would do a pressure and vacuum test on the unit.
BTW, what did you think of TC's work, did they do well by you?

 

[Rhc]

Sounds like you tried to cover all the bases...
questions...
did you check the drag of the shift cable with it disconnected at both ends with a fish scale? should be not more than 2.5 lbs, the drag on the cable is pretty important...
also if you shifted the lower unit when it's off the boat, with someone turning the prop shaft or the driveshaft, does it shift relatively easily from N to F and from N to R?
Is the shifter bellcrank in pivot housing moving easily, these can get crudded up by deposits from water getting past that gasket...
Stiffness can be the control, control remote cable, transom shift cable, the shifter bellcrank in the pivot housing, or inside the lower unit. Since you just had yours re-done, that's probably not it.
Based on what you're saying about what you tried, it does sound like it could be the control unit. My original OMC one shifts very easily, almost too easily, the neutral detent is not that positive.
the water in the gear oil could have been the seal in the water pump adapter, TC has a video that shows how to change that, they also sell a modified part with an extra seal in addition to the standard one, I would do a pressure and vacuum test on the unit.
BTW, what did you think of TC's work, did they do well by you?

So I will do some more investigation but weather is turning bad so I’ll be limited. I will measure the PULL and see how that works out. I have the drive off so I’ll do a test with it free standing. I know I failed to have a person always standing at the back spinning the prop when I’m doing the shifting, but mostly I went down myself and double check if I was concerned. Not a good solution, but maybe with a freestanding unit I can get a better feeling for this. Require more investigation on the shifter before committing as the cost appear to be in the $500 CAD Vicinity. Seems outrageous to me. I have the boat in a side yard here and I can remove that and look at it this winter.
I definitely had some suds in the drive oil probably due to overfill. Yes I did have water as well. The leak is at the top cap on the upper drive as I think it wasn’t quite as tight as it should’ve been. Never had a problem there before - I did not checked bolts before landing in the water. TC is about three hours away from me so I don’t think I’ll be getting them to do a pressure or vacuum test. I may rig up something here.
I did look at TC Marine video at the pump location. Hope that isn’t the problem here. I’ve enjoyed working with Wayne Coyle TC. Marine. He is the general genuine article. Looks like he has done thousands of these drive rebuilds. He Agrees with you & others - the oil shouldn’t interfere with the efficiency of clutch dogs. I’m still not convinced that the hydraulic pressure wouldn’t make some changes but nobody else seems to agree. This is something between me and AI – we seem to agree on this one - scary based on some recent Calc’s it did with me. I’ll keep you posted if I do any work this winter. Thanks for your input as always.

 

[Lou C]

I bought both the pressure & vacuum testers and as long as you have a boat with either I/O or outboard they are useful to troubleshoot problems and water in the gear oil is a common issue with both.
I would be curious to see what the drag on your cable is, and if the bell crank in the pivot housing is moving freely.
I have spoken to Wayne as well and I am going to send a spare lower unit to them to go thru this winter…
As far as hydraulic pressure I know that adding water to gear oil tends to raise the viscosity of the oil + water mix. When I had water in the engine oil my oil pressure on the gauge was definitely somewhat higher. Could this affect shifting? Who knows?!
The most important thing with these is low drag on the shift cable and the whole shift system will including the remote control….

 

[Rhc]

I bought both the pressure & vacuum testers and as long as you have a boat with either I/O or outboard they are useful to troubleshoot problems and water in the gear oil is a common issue with both.
I would be curious to see what the drag on your cable is, and if the bell crank in the pivot housing is moving freely.
I have spoken to Wayne as well and I am going to send a spare lower unit to them to go thru this winter…
As far as hydraulic pressure I know that adding water to gear oil tends to raise the viscosity of the oil + water mix. When I had water in the engine oil my oil pressure on the gauge was definitely somewhat higher. Could this affect shifting? Who knows?!
The most important thing with these is low drag on the shift cable and the whole shift system will including the remote control….

Yes i will look into drag. I have the drive off and hung in garage to drain. So while hanging I worked the shift rod and it moves well. Slightly firmer going down then up -- not sure if that is Fw or Rev. I will fill fluid and post the drag results. Remember it did shift okay when i shifted with cable off at the remote console shifter!! But i feel the action is intermittent. For instance the last few times on the water after running say 10/15 minutes it would shift in and out satisfactorly!!
My first check on shift rod is Neutral up @1/4" to 1/2"and neutral down is 7/16" Remember neutral position detent is flexible. No matter where neutral is the total travel stroke is say 11/16" to 15/16". The stroke seems short?? The cable stroke is much more but the clutch dog angle may affect the total stroke --- any comments.

 

[Lou C]

OMC Cobra Sterndrive Tech Info

don't know if you have seen this site, but there is some original OMC documentation on this site, that will help explain the finer points of adjusting these, like:
setting the shift rod height (very important)
how much the travel of the shift cable should be (also very important)
measure cable drag (not more than 2.5 lbs)
So, have you measured the shift rod height?