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OMC lower unit I am baffled

D

Drake Dietz

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"88 bayliner with a 5.0 chevy

"88 bayliner with a 5.0 chevy and OMC stern drive. Getting it ready for summer, first year I have had to wineterize and commision. Drain the lower unit to replace the oil. Was not cloudy or anything. But figured it should be done. Drained it, and wnet to fill using the next to lowest fill port. Took out the overflow plug on the side and commenced to fill. All done and wnet to put the overflow plug back in and there are no threads on the housing. Trying to attach a picture. It was screwed into something when I took it out. Only thing I can think is previous owner put a nut or helicoil in and it has now fallen into the lower unit. Any suggestions? I also had a lot of oil running out by the prop, so need to pull the lower unit to replace a seal for sure, but can not figure out what to do about the plug."
 
"Drake my friend, unfortunatel

"Drake my friend, unfortunately you have fallen prey to the old "don't remove that screw" Cobra trick. The one you have removed was never meant to be taken out and at one time your Cobra would have had a Cobra emblem badge over it so you would never had known the screw was there. All is not lost though however you will have to remove the drive, what has happend is a very thin piece of metal like a nut plate was holding that screw in and it has fallen down inside the water passage. Remove the drive and fish it out and you can put it back together and then make a mental note never to do that again. See picture below and #14 in the bottom left corner is the screw plus the thin piece that it screws into.

For the oil you need to pump it in until it comes out the vent screw (not the one you removed) it is closer to front of the drive and a little lower just above the cavitation plate (same kind of screw that you pulled out to drain. Once it comes out the vent, screw the vent screw back in and keep pumping cause your only halfway there. The dipstick on the very top of the drive should be sitting loosely in the hole, pump until the oil hits the fill mark on the dipstick and then screw it in. The drive should hold 64 oz of fluid (if it was empty) If you don't fill it completely then your upper gears will get toasted.


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"Thanks again Bob. When you s

"Thanks again Bob. When you say remove the drive, do you mean upper and lower? Lower looks pretty straight forward, but I am hesitant on the upper drive. Is it possbiel to get to that plug once the lower half is removed? I did purchase the online manual through Seloc, but that upper portion looks intimidating."
 
You'll want to remove the

You'll want to remove the complete drive as a unit (upper and lower). Remove the six nuts and slide it right off. It will help a bunch to support it from above with a hoist.
 
"Yes...as Marada1 says, the wh

"Yes...as Marada1 says, the whole drive always has to come before you split the halves ( you don't need to split them) because of the shift rod, you have no access to it until the drive is off and you need to turn it before splitting, it will make more sense to you once you have it off. Removal is pretty straightforward, leave the gearshift in neutral, remove the nuts holding the rod between the 2 trim cylinders, remove the 6 nuts holding the drive on and pull out slowly, best to have another hand or 2 to grab the drive shaft once the u-joints come out. You'll need to pick up a new gasket/o-ring set from the dealer. Also suggest you borrow, rent, buy (eBay) an alignment tool to check it before putting the drive back on. Of course while it's off is a great time to grease the u-joints, check the gimbal bearing for smoothness and the bellows for any tears or old age (getting stiff)."
 
"Marada1, so once off I will n

"Marada1, so once off I will need to disasemble the entire thing to get to that piece of metal? I have to think there is a way to get to it without ripping the entire thing apart."
 
"Very well then, looks like a

"Very well then, looks like a weekend project. Thanks for all the help."
 
Bob has covered it in detail.

Bob has covered it in detail. Pay close attention to his directions for oil filling. DO NOT fill this drive from the bottom drain. It can cause air pockets that will cause you much misery.
Good luck
 
"two last questions. 1) w

"two last questions. 1) where did you find the parts diagram, I have nothing with the Seloc manual that I can find. 2) oil coming out by the propeller shaft is going to need which bearings?"
 
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