OMC COBRA Lower removal

KrisHall

Seaman Apprentice
Joined
Jan 15, 2005
Messages
41
Hey Guys,

As some of you know I've been in the middle os a OMC Cobra saga that is on going.

Cracked block, manifolds, and I suspect heads, and last night with a flashlight I found that the lower outdrive box has about a six inch crack in it. I also found that there is no oil in the top filler (next to the water pump.)

Needless to say the entire drive needs to come off but I want to get that lower off first and start in on finding a used salvage case and get that out of the way first (tear into it in stages.)

Im glad I found this before ordering the engine and aftermarket manifolds...No point in that expense unless there is something that can be done with that outdrive.

I've got the 4 side bolts off and the two bolts under the trim vaine and it will drop about 3/4 inch but will go no farther. It looks as though there is (looking through the gap) a bolt on the forward side of the drive stopping it from dropping out and it looks like it is buried in the intermediary somewhere.

Am I going about this wrong? Does the whole assembly (top, intermediary, and lower) have to come off in one piece first?

I've got a manual on order...But will be a few days before I get it.

thanks in advance guys,

Kris
 

Boomyal

Supreme Mariner
Joined
Aug 16, 2003
Messages
12,072
Re: OMC 800 Lower removal

Re: OMC 800 Lower removal

You did not state a year and the drive cannot be both a Cobra and an 800. I could not tell from your pics either. Do you have a Macro setting on your digital camera? It really sharpens up those closeups.
 

KrisHall

Seaman Apprentice
Joined
Jan 15, 2005
Messages
41
Re: OMC 800 Lower removal

Re: OMC 800 Lower removal

I do not know the difference myself...But the original manifolds are Stamped 1987 and the Hull is titled as an 1988...I'll snap another pic showing the whole drive unit.

My cam is an older HP 318...I can increase resolution a bit.

Kris
 

Boomyal

Supreme Mariner
Joined
Aug 16, 2003
Messages
12,072
Re: OMC 800 Lower removal

Re: OMC 800 Lower removal

You have a Cobra KH. Edit the title in your post, as such, and you are liable to get more input. These drives are more like the mercs and volvos. I'm basically a stringer guy so I can't help you.
 

KaGee

Admiral
Joined
Aug 14, 2004
Messages
7,069
Re: OMC 800 Lower removal

Re: OMC 800 Lower removal

That crack looks repairable where it's at. Was it impact damage??
 

KrisHall

Seaman Apprentice
Joined
Jan 15, 2005
Messages
41
Re: OMC COBRA Lower removal

Hi guys,

Boomyal: I'm looking around the forum thread and am totally baffled on how to change the thread title.

KaGee: I have had this boat in the water once which was the summer of 04 In Crystal River Bay <Florida>. I remember tagging a couple of things on the northwest area of the bay at idle speed and the new michigan match prop reflects this with a couple nicks. I raised the drive a bit and problem solved. I have not slammed into anything at high speed. So impact damage I tend to think possible but not probable.

Given my lack of knowledge of stern drive boats because I've never had anything prior except 2 stroke outboards it is more likley that the crack is from ice...Not only did I fail to winterize the engine in Arkansas 20F weather...But I also left the drive in the up position where it would catch rain water.

Where I live/lived in florida this stuff is not a concern because it rarely freezes and if it does freeze it's only for a few hours through the night.

There is another thread about this same boat called OMC 4.3 white sludge.
 

KrisHall

Seaman Apprentice
Joined
Jan 15, 2005
Messages
41
Re: OMC COBRA Lower removal

If it's repairable; after I get it off and clean the oil out good...I'll find me some aluminum or brass rods and fire up my acetylene/O2.

Cheaper than the ones I see currently on ebay for $1500
 

KaGee

Admiral
Joined
Aug 14, 2004
Messages
7,069
Re: OMC COBRA Lower removal

If you clean out the crack and sand the surface, JB WELD would work, provided the crack is not internal into a water passage too. But, I think you are safe there. You can patch and pressure check.
 

cobra 3.0

Lieutenant Commander
Joined
Jul 31, 2003
Messages
1,797
Re: OMC COBRA Lower removal

You need to take off the whole thing first to disassemble. Lower the drive to make it perpendicular to the boat. Take off 6 bolts and one main shaft holding the cylinders. There is a shifter rod with a black metal slotted piece that needs to be moved to be able to split the upper and lower units. You'll see this better when it's off. Carefull that drive is heavy.
 

KrisHall

Seaman Apprentice
Joined
Jan 15, 2005
Messages
41
Re: OMC COBRA Lower removal

I've already got the engine and electrical harness removed from the boat...Look's like I'll have to bleed the hydraulics off to get the drive down...Only thing I can think of...any Ideas?
 

jfcar

Cadet
Joined
Jul 22, 2006
Messages
28
Re: OMC COBRA Lower removal

Since you already have the power disconnected try supporting the lower unit (out drive) taking weight off the trim/tilt cylinders, remove the rod and then slowly lower the out drive to the down position. Remove the oil level plug (plug on top of out drive) and get a hook bolt 1/2" 13 thread to use as a lift eye for a hoist and screw it into the level plug hole. Used a hoist to hold the out drive in place, remove the six nuts and pull drive away from the transon.
 

cobra 3.0

Lieutenant Commander
Joined
Jul 31, 2003
Messages
1,797
Re: OMC COBRA Lower removal

Don't drain the cylinders! Just remove the nut at one of the ends of the through and through bolt/rod holding up the cylinders. Lift the drive slightly and pull the bolt/rod through. The drive isn't THAT heavy. Maybe a 100 lbs or so.( because I can carry the drive)
 

jfcar

Cadet
Joined
Jul 22, 2006
Messages
28
Re: OMC COBRA Lower removal

Also I didn't mention you should support the cylinders so thay didn't hang by hoses.
 

KrisHall

Seaman Apprentice
Joined
Jan 15, 2005
Messages
41
Re: OMC COBRA Lower removal

Thanks Cobra,

I've got the cylinders off in the way you suggested, however it was not an easy job due to minor corrosion and apparently no grease in years/decades.

Yes once I got the nut loose on one side I tested the weight of it...It's not bad at all. I'm a fairly able person, I can take that drive and throw it around like the suit case in the old Gorilla sampsonite commercial. I took the prop off to keep from slicing myself up while doing this.

Anyway, I got the rod out and the 6 nuts/washers are off...And for the past 45 minutes Mr. Magilla Gorilla (me ) has been yanking, jerking, jolting, pushing, pulling, beating, and cursing that drive!

I can see that the housing is loose, moving freely on all six bolt studs but it is obvious that a gear or bearing therof is holding it in somehow. So I pulled off the top filler plate to take a look...aside from some stagnant water rust on top of the forward gear...the gears and from what I can see of the bearings are pristine (no wear or chips ) although there was not a drop of oil in it.

I happened to watch on the starboard side as I was jerking it around and a massive amount of white powder (aluminum oxide) was falling out...My first thought was, "It's from Florida and it's got a KILO in it :} IM RICH8) "

Is there something more than those six bolts on the cobra drive that would hold it in?

I took the cylinders off from the aft end and left the forward end connected so they are not suspended by the hoses.

Bigger Hammer?
 

Gary H NC

Fleet Admiral
Joined
Dec 1, 2005
Messages
8,972
Re: OMC COBRA Lower removal

Sounds like you are having fun anyway...LOL 8)
Maybe its the drive shaft stuck in the engine coupler...Thats a good question for Don S.

BIG pry bar??:%
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Re: OMC COBRA Lower removal

If this drive hasn't been off in awhile could easily be the shaft is stuck in the coupler.

I had the same problem with one a long tie ago. I eventually used a large screwdriver and pried on it being extremely careful I didn't use too much force to break or damge the housing.

I have heard horror stories of people having to cut the shaft from the boat side...I hope yours isn't that far gone.
 

KrisHall

Seaman Apprentice
Joined
Jan 15, 2005
Messages
41
Re: OMC COBRA Lower removal

Hey Bruce,

Thus far the only damage I've done to it is two fold...

The head twisted off the water plug on the port side. I heard something fall inside when it did.

and one of the heads of the top plate bolts turned off. So now I got a stud soaking up some "PB nutbuster" I may have to drill and easy it out. I got a bunch of those screw extractors (aka easy outs ) from back in the day when I worked for Raytheon, Boeing. etc.

I can get the drive to move aft about 300-400 thousandths jerking it around.
 
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