OMC Cobra Lower Unit Reoval

[brutustitan]

Can the lower unit of an OMC Corba stern drive be removed without pulling off the entire outdrive?
Is there a way to rotate the shift rod or unscrew it from the detent lever?

 

[danond]

Re: OMC Cobra Lower Unit Reoval

Sounds like you should have a manual before you start this project.

 

[brutustitan]

Re: OMC Cobra Lower Unit Reoval

I"ve got a Seloc and the OMC Cobra Service Manual.
They both say to remove the upper first.
I don't like what I hear about aligining the driveshaft when installing.
I'd like to find a way around it.

 

[metro3pilot]

Re: OMC Cobra Lower Unit Reoval

You need to remove the whole drive,

plus when you remove the whole drive you can inspect the bellows, gimble bearing, and lubricate the splines, shift bellcrank, and U joints.

get an alignment bar, new gasket for the install, and a way to measure the shift rod height, may also want to get the 2 grommets for the water tube as well.

alignment is a simple procedure adjusting 2 easily accessible engine mounts, nothing to be afraid of.

why do you need to split it anyway ?

 

[sea wolf]

Re: OMC Cobra Lower Unit Reoval

It can be done, cuz I've done it. Only once. Trust me, the easist way is to pull the whole drive off.

 

[brutustitan]

Re: OMC Cobra Lower Unit Reoval

I"ll give it a shot removing the whole unit.
Thanks for the tips.
I found an alignment bar on ebay for $50 +.

 

[Lou C]

Re: OMC Cobra Lower Unit Reoval

Removing the whole thing is actually pretty easy, but it is fairly heavy, so you need a piece of wood to rest the skeg on or some help with it. I built a stand to make it easy on the back. I would not try to separate the lower from the upper when they are on the boat, because the shift lever engages the bellcrank that is in the pivot housing, and trying to force it off may bend something. The drive has to be away from the pivot housing by an inch or two for the shift lever to disengage the bellcrank.
As far as reinstalling, the reasons that you can have trouble is that the engine could be out of alignment (needs to be corrected right now, or else the coupler can be ruined), the old style Cobra driveshaft bellows was just barely big enough and the ujoints would get hung up on them. There is a new style one that is quite a bit bigger. If you have the alignment bar (I got one too so I can do the yearly R&R myself) checking it is easy. Do a search here there is tons of info on it. Make sure you check the gimble bearing, ujoints, and bellows carefully.
for the official R&R procedure with pix from factory manuals:
www.crowleymarine.com
look in product support, OMC Cobra drives.

 

[brutustitan]

Re: OMC Cobra Lower Unit Removal

Re: OMC Cobra Lower Unit Removal

Finished in 2 hrs.,plus impeller and oil refill with my son.
I can't wait to repower soon.
Thanks again.

 

[brutustitan]

Re: OMC Cobra Lower Unit Reoval

I'm having trouble with water getting to my pump.
We ran it after the install, the temps. climbed to 250.
Removed impeller and noticed one side (the left )was getting water but the right wasn't.
Removed lower unit to check seals around the water pickup tube, and the upper unit seal wasn't up in the hole, just around the tube.
Put it back were it belonged and re-installed everything.
Fired it up again, temps. climbed,shuter down.
Removed impeller housing again,this time no water at either side.
What's up, an obstruction?
It seems that water isn't coming UP from the lower unit.
Never had this before with the older replaced lower unit.

 

[brutustitan]

Re: OMC Cobra Lower Unit Reoval

Also, the new lower drive came off of a 1993 four winns 5.7.
My boat and the upper drive is a 88' bayliner 5.7.
Any un-similarities that would cause a situation like this pairing them together?

 

[bruceb58]

Re: OMC Cobra Lower Unit Reoval

Its possible you have an obstruction after the water pump. There is a power steering cooler that the water goes through before it hits the thermostat housing. It is possible that it got clogged.

What condition are your manifolds and risers. If they are plugged, you will also get limited water flow.

To see if air is getting in somewhere, you could plumb in some clear hose between the hose that goes to the thermostat housing and the thermostat housing itself. If you see alot of air, you have a leak somewhere.

I know it seemed like it was working with the old unit. Just exploring possibilites.

 

[metro3pilot]

Re: OMC Cobra Lower Unit Reoval

chances are the tube is not in correctly since you had water then all of a sudden you did not have water, it comes in on one side goes thru the impeller and on to the engine thru the other side.

It could possibly be clogged but not much too clog between the lower and the impeller check your screens on your lower.

I found it easier to turn the unit upside down, install the tube and grommett in the upper and then mate the lower while the unit is still upside down, it should slide together easily, if you have to force it,something is not ligned up correctly.

you can test the water flow to the engine by removing the supply line at the Thermostat housing, hold the hose level with the housing and start the engine for a few seconds if you get a 2-4" stream then you are getting sufficient water to the engine.

when is the last time you changed your thermostat ?

 

[brutustitan]

Re: OMC Cobra Lower Unit Reoval

You were "oh so" correct my friend.
Pulled the drive again ang re-aligned the pickup tube and seals.
Now water came out the right side of pump with muffs on like a champ.
Bolted it up and ran it in a tub.
Overheated again.
Put my old (good shape) impeller on with a new seal and presto.
The Marina sold me an impeller that was too big.The input shaft slot was just spinning.
Thank you