1988 OMC Cobra. Boat takes on water and is slipping

[horns011]

I have a 1988 four winns 180 horizon with a 4.3L OMC Cobra outdrive. When out of the water the prop spins fine, once in the water the boat idles around easy but will not speed up. Just changed the hub in the prop so that's not the problem. The gears in the lower unit appear to be in great shape, The spline also looks fine. Also the boat is taking on water quickly I changed both bellows, water pump O ring and lower unit gasket also shift cable boot. Could the leak be related to the slipping? I heard it may be the engine coupler but I'm not for sure. Any Ideas would be greatly appreciated. thanks

 

[dubs283]

Re: 1988 OMC Cobra. Boat takes on water and is slipping

with the boat out of the water and the engine OFF, out the drive in FWD gear and spin the prop counterclockwise

the prop should lock in gear and not turn at all, if it does and you are sure the prop hub is not slipping and you are not turning the motor over while spinning the prop, you have an issue with the engine coupler or the drive internals

you will have to pull the drive to properly inspect the coupler/driveshaft splines/engine alignment

the shift cable boot? on the end of the shift cable tube?

the tube attaches to the inner transom plate and is a pain to replace

i don't see any relation to the water leak and the slippage

 

[horns011]

Re: 1988 OMC Cobra. Boat takes on water and is slipping

I have the lower unit off right now, but before pulling the engine i will set it back on and try turning the prop in gear. If it spins I will change the coupler. Is there anything I should know before pulling the engine and changing that coupler? This is my first boat so I'm trying to learn things as I go. I appreciate your help

 

[dubs283]

Re: 1988 OMC Cobra. Boat takes on water and is slipping

you should visually inspect the coupler now that the drive is off

shine a flashlight through the bellows and look

if the splines are pointy or missing/shredded you definitly have a bad coupler, same with the drive shaft splines

another sign is a grey, dry grease substance on the driveshaft splines

it could also be the rubber hub in the coupler that has spun free

if you do pull the engine to replace the coupler you should also replace the shift cable tube

 

[horns011]

Re: 1988 OMC Cobra. Boat takes on water and is slipping

I dont think the splines were hurt but there is a lot of gray grease on the driveshaft.

 

[danond]

Re: 1988 OMC Cobra. Boat takes on water and is slipping

Your boat is at the prime year range for rot to finally weaken the transom enough to cause a leak. If your transom is rotten and allowing water in through the gimbal seal, you need a transom replacement to fix the leak.

The other issue could be the lower shift cable tube, but I find that doubtful. They don't typically fail.

Look for cracks in the gelcoat around the bottom of the drive on the outside of the transom. If it's cracked, your transom's very likely rotten, and you've found your leak.

My site has info on finding rot and replacing transoms in I/Os.