OMC Cobra - Prop Spins in Neutral

[rybad]

I have twin OMC Cobra's. My port outdrive prop will spin while running, but with the engine in neutral. I did just change and adjust the transom shift cable. But this happened before the change as well. In fact, I though this change would help, but it didnt.<br /><br />I can stop the prop by hand, so I know it's not actually in gear. The drive will also shift into and out of gear fine. I just don't understand how the thing can spin if it's not in gear. It gets spinning pretty fast too. Especially if the drive is raised up, it will spin faster.<br /><br />Could the gear on the clutch dog be barely enguaged?? That wouldnt make much sense, but other than that, I dont understand it.<br /><br />Any suggestions?

 

[achris]

Re: OMC Cobra - Prop Spins in Neutral

David,<br /><br />It's all about the friction inside the gearbox. It's completely normal and it won't do it in the water. If the dogs were just picking up, man, you'd be hearing it! They make a terrible noise. Uck!<br /><br />Chris........

 

[Haut Medoc]

Re: OMC Cobra - Prop Spins in Neutral

Suggestion: Don't touch a spinning propeller. I don't know OMC so wait for those who do to post.....J

 

[rybad]

Re: OMC Cobra - Prop Spins in Neutral

Thats what I thought (I would hear it if it were semi-enguaged).<br /><br />So, my guess is that the gear oil is creating an effect like a tourque-converter on the propshaft??<br /><br />Mine actually does still spin while in the water, although much slower under that load. Is this somehting I need to worry about, or is it an indication of a problem, or something not quite adjusted to spec?<br /><br />Thanks for your fast reply.

 

[QC]

Re: OMC Cobra - Prop Spins in Neutral

Just a quick semi-related question. OMC Cobras don't have dog clutches do they? I thought the whole deal with the Cobra was a cone clutch, right?

 

[achris]

Re: OMC Cobra - Prop Spins in Neutral

Nothing to be concerned about. Maybe you should be using a lighter oil. What oil are you using?

 

[rybad]

Re: OMC Cobra - Prop Spins in Neutral

I use the OMC/Jon./Env. Ultra-UPF or Hi-Vis. Right now, I have the Ultra in it. But it's done this ever since I owned this boat which is 3 years. And I know they guy that owned it before me probably used the cheapest oil he could find (not very bright individual). But it has always done this.<br /><br />I guess I was just hoping someone would either tell me that there is a problem, or there is NOT a problem (which you have indicated).<br /><br />I just wanted to be sure that I didnt "ignore" a potentially expensive issue by not fixing the problem.<br /><br />Thanks for you help.

 

[rodbolt]

Re: OMC Cobra - Prop Spins in Neutral

you have no problems<br /> its normal. its the friction of the oil. <br /> the early king cobras had a cone clutch, later versions were a dog clutch but were a bit heavier than the standard cobra but not so much you readily noticed. the dog clucth king cobra was popular with 28 bayliners and 460 fords.<br /> the 95 and up jopint venture cobra/sx was a cone clutch but OMC sold off the JV project to volvo in late 95 early 96 I think.

 

[rybad]

Re: OMC Cobra - Prop Spins in Neutral

Thanks guys for the information.

 

[QC]

Re: OMC Cobra - Prop Spins in Neutral

rb,<br /><br />The heavier-duty drive had the dog clutch? Seems backwards. My understanding of the Volvo now is that torque limitations are what forced them into the duo-prop. Accurate?

 

[rodbolt]

Re: OMC Cobra - Prop Spins in Neutral

nope<br /> for about 2 years OMC tried a cone clucth. then quietly shifted the king cobra label to a unit with a V8 style case. volvo has used a cone clutch since the early 60"s. started out as a bus transmission. the 290 upper is the same as the DP. almost all volvo units share the same cone clutch design. some will even share upper parts. the cone and shoe materials have changed but not due to horsepower. the design of the volvo lower is it can rotate either way. the input rotation to all cone clutch volvos is left hand, wont work at all with right hand input. the reversing was simply by changing the shift link and prop. however the in the upper there are 2 driven gears. in one position the cone is locked to the upper gear and the other its locked to the lower. the top cover also retains the upper bearing. so if your main(fwd) thrust is taken from the upper the power may overwhelm the upper bearing housing. which is why the duo takes the power off the lower. and with a pair of duo props you dont need counter rotating. I did not say the dog clutch was heavier duty than a cone clutch king cobra. I said the dog clutch kings were heavier than a standard cobra. big bayliners of the late 80's used a lot of OMC 340HP 460 fords with dog clutch cobras and king cobra decals. I stillthink of the kings as being cone clutch models but not all were. its confusing

 

[Lou C]

Re: OMC Cobra - Prop Spins in Neutral

I have a 1988 OMC shop manual and if you compare the size of the lower units from the small block V-8 to the big block there is quite a difference. The 460 Fords/King with dog clutch took 108 oz of gear case oil, whereas the 262/305/350 took 64 oz of oil.<br />I have only seen one of the post 1990 Kings with the cone clutch on a 1991 FW Liberator with a 454. That drive was huge in comparison to these, way bigger and beefier looking. Too bad they are not still in business.