OMC 3.0L 4Cyl -- Lost propulsion

[mc1711]

When cruising at moderate speed my boat suddenly lost propulsion. Motor kept running and went up in RPM but no power was transferred to the prop.<br /><br />It felt in exactly the same way as when a car is put into neutral by mistake while the foot is still on the gas. <br /><br />Any ideas on what could have happened and what it will take to fix it?<br /><br />The motor still runs although it feels a bit unstable now compared to earlier.

 

[WillyBWright]

Re: OMC 3.0L 4Cyl -- Lost propulsion

Welcome to iboats. <br /><br />Check the gearlube for metal. Failing that, you may have a spun prop hub. I'd be amazed if a 3L did that. I think it's a lot more likely that you have a spun engine coupler, probably from an alignment problem. They're not awful to replace on a 3L, but you have to have the right stuff. The motor has to come out.

 

[Boatist]

Re: OMC 3.0L 4Cyl -- Lost propulsion

MCX<br />First off welcome to the board. <br />Really for anyone to help you we need to know the year of your engine.<br />OMC 3.0L 181 cubic inch 140 hp motor have changed a lot over the years.<br />What you have decribed is very common problem on the OMC 400 Stringer outdrive. I think the years it was made is form 1979 to 1985. This drive has a 1/4 round gear on the port side of the outdrive to raise and lower the outdrive. Motor trim is done by raising and lowering the front of the motor.<br />If it is that year then it is likely the water pump short drive shaft and the mateing shaft. This would also cause the water pump not to turn so if you ran it long enough it would also get hot. <br />This shaft drives the water pump but also the main drive shaft for the lower unit. It would cause no metal fileing in the gear lube. Broken ball gears would cause the same problem but if you were running with the drive in the down position then it is more likely the water pump short shaft and the mateing spline shaft.<br /><br />If this is the problem and you can not do the work your self then I think be be $800 to $1000 to repair. This would be for the two shafts and a water pump and labor.<br /><br />If it is 1985 or newer then should be a Cobra drive. This drive use two hydraulic cylinders to raise and lower the outdrive. This motor is completely different. I do not know the Cobra drive but ther plenty of good people here that do.<br /><br />So let us know the year and we can help.

 

[mc1711]

Re: OMC 3.0L 4Cyl -- Lost propulsion

Thanks guys. <br /><br />The boat itself is from 1989 and although I can't confirm it, I would expect that the engine is from the same year.

 

[Boatist]

Re: OMC 3.0L 4Cyl -- Lost propulsion

MCX<br />Ok if it is a OMC 1989 then should be a Cobra Drive. Does it have two hydraulic cylinders to raise the out drive just above the caviatation plate?

 

[mc1711]

Re: OMC 3.0L 4Cyl -- Lost propulsion

Yes, it does have the two hydraulic cylinders

 

[Boatist]

Re: OMC 3.0L 4Cyl -- Lost propulsion

I know very little about the cobra drive but many on here do. I dout it is a spun prop as with a spun prop you can idle back to the dock.<br /><br />At least we know it is a OMC Cobra outdrive. Now someone can help you.