Leaking water through Transom OMC Cobra

eldrive

Cadet
Joined
Jul 13, 2004
Messages
11
(Sorry this is long!)

Hey All! Been a while since I have posted on this site, but am back with a new problem and I having been using the search function and perusing the archives and I believe I have a good grasp on what is going on but hope to get some more input and maybe this will help someone else down the road! I am very mechanical and wrench daily on motorcycles for a living so can do pretty much all, but have no experience with fiberglass/transom repair etc etc.

Ok, 1988 Reinell 17ft with a GM 3.0 and OMC Cobra outdrive.

Boat was very well maintained with just over 300 hours, I was actually surprised at how well this thing ran when I got it and it was serviced regularly every year, every thing was greased and adjusted properly, shifts with one finger as they are supposed to (I hear that is a problem with the OMC's) and every single thing save for the horn works on this boat. The guy I got it from knew nothing about boats, but he knew the original owner since they worked together so the boat has had a good history and regular maintenance by a shop. Only operated in fresh water, lake or river.

Only problem when he sold me the boat was that water was coming in from somewhere and he did not know where...in fact he had put some MarineTex on the bottom of the hull where the boat had been beached a few times thinking that was the problem....it wasn't.

I took it out once and the after about 3 hours the bilge had water up to about 2-3 inches below the oil pan! At this time the bilge pump had some crap in the line and was plugged so it did not work, but I fixed that in about 5 mins when I got it home and works great now.

So I took the boat to the launch ramp yesterday to put it in and see if I could find the leak. Prior to this I closely inspected the driveshaft bellows and it is in very good condition with no tears or holes. The shift cable also does not seem to have any problems. The exhaust bellows does have some cracks and holes but as I understand it that is not a problem.

So after lowering it into the water and getting down into it I could see the water coming in from just above the drain plug hole. It comes in somewhat moderately, cascades down like a very gentle waterfall about 3 inches across.

The area I am pointing to with the orange rod is where the water seeps from...just behind that metal plate. (NOTE: The drain plug assembly is removed to repair the kinda poor job done on it before, but it did not leak)

Boat008.jpg




Here is a shot from outside of the boat...(note I have the Anode part removed from the bottom of the drive to have a better look!)

It seems to me that when I pulled the boat out of the water and stopped on the ramp to have a look, the water came back out in this approximate area that I am pointing to!
Boat002.jpg



So I realize after reading a number of other threads here that I probably have some degree of rot or "soft transom". I have physically tried to move the outdrive up and down and see no play or flexing, I have also tapped around the transom and it appears solid, but I realize I need to drill into it to see how much rot and am going to take it to a local boat repair guy tomorrow to do just that.

I did get back into the boat and put a socket on one of the nuts seen in the first picture and it easily turned a revolution or so before becoming somewhat tight....I realize that it should not be loose and tightening it down is just pulling in the transom, or drive so to speak. I also realize that the engine and drive need to be removed to repair the transom and fix the seal...no problem I can do that...my question is:

Can I tighten this down and maybe use a marine grade sealant somewhere to get me through this season so I can use the boat and then pull it all apart in the winter??? I understand that tightening it down may affect the alignment and I would have to compensate (I think) by adjusting the front engine mount.

Ok, I think that is it, I am probably forgetting something but will add more later if I remember. Thanks for any and all advice on this! Would really like to fix this for the summer and then ovehaul in the winter....I just moved to a new house TWO MINUTES from the boat launch! LOL!!
 

eldrive

Cadet
Joined
Jul 13, 2004
Messages
11
Re: Leaking water through Transom OMC Cobra

Forgot to ask, is there a preffered brand of sealent...if I can even do that....thanks!
 

Coors

Captain
Joined
Dec 8, 2006
Messages
3,367
Re: Leaking water through Transom OMC Cobra

It might be an easy repair, just start probing, to see how far the rot goes.
 

eldrive

Cadet
Joined
Jul 13, 2004
Messages
11
Re: Leaking water through Transom OMC Cobra

Yeah I figure it is not so bad considering the condition of the rest of the boat, but will probably still require removal of the engine/drive, any thoughts on the quick fix/temporary part of it?
 

wakeboarddude

Seaman Apprentice
Joined
May 21, 2007
Messages
36
Re: Leaking water through Transom OMC Cobra

Check out this site....
http://www.rotdoctor.com

I just redid all the back end of my boat, ripped all the rotten wood out down to nothing and pulled the wood off the transom. It was a big job, but before i started i was looking at these products to "patch it up". Theres lots of great info on this site about repairing transoms. The stuff you'd be looking at is the penetrating epoxy.
Good luck, i know its not a small project redoing the transom/floors.
 

Gary H NC

Fleet Admiral
Joined
Dec 1, 2005
Messages
8,972
Re: Leaking water through Transom OMC Cobra

The penetrating epoxy will only work if the rotted area is dried out.That would mean removing the drive and gimbal housing anyway. It works for early stages of rot but if it is too far gone you need the transom replaced..
 

Robj

Lieutenant
Joined
Mar 22, 2007
Messages
1,441
Re: Leaking water through Transom OMC Cobra

Now that you tightened the bolts you should try it to see if you slowed down the leak. Otherwise you could use a sealer such as 3M 4200 to seal between the transom and the shield, but I would think that for that to work as a temporary fix you would have to remove the outdrive and transom shield so you can get the sealer inbetween the shield and transom.

Otherwise you can fix it properly by replacing the wood, it should not take you more that 2 to 3 days. That is how long it took me to do mine.

Have a great day,

Rob.
 

Gary H NC

Fleet Admiral
Joined
Dec 1, 2005
Messages
8,972
Re: Leaking water through Transom OMC Cobra

2 to 3 days is a heck of a job. Especially on an I/O:D

I wish my transom rebuild was going that fast. I'm 4 days into it with skinned up knuckles and fingers and still have more rot to remove.I just keep chipping away at it...:)
 

wakeboarddude

Seaman Apprentice
Joined
May 21, 2007
Messages
36
Re: Leaking water through Transom OMC Cobra

Gary your right that epoxy only works with dried out rot. Thats why I just ripped everything out to nothing and started all over with new wood. Definately 4 + days to do a real good job, no shortcuts.
Good luck with yours Gary, now if ony I can get my boat started I'd be on my way!

Eldrive. not sure exactly how your seal works there as I have an omc, but i had a similar problem and had to pull the rubber boot off clean it all and reseal with that 3M Marine sealant 5200 stuff.
 

kucharskiauto

Recruit
Joined
Jun 2, 2007
Messages
1
Re: Leaking water through Transom OMC Cobra

hi i have the a leakas well but mine is coming thought the bellows boots i asume the top as a slice in it ujoints in there and bottomis almost gone ibought a kit how long does it take to replace an is ther a sight i can get free info on how to replace? was going to tackle it in the am thanks mike:eek::eek:sorry for the spelling im on my phone daa
 

sea wolf

Lieutenant Junior Grade
Joined
Apr 3, 2002
Messages
1,219
Re: Leaking water through Transom OMC Cobra

Hey Eldrive, before u start ripping that transom off, make sure that's where the leak is. I have an 87 starcraft with the 3.0 OMC Cobra that was taking on water in the exact same location you describe. Come to find out, there's a seal in the transom between the engine & lower unit that was shot. Problem is, I had to pull the engine to find it, as it's not mentiond in any manuels. Might be worth investigating, as it's a hell of a lot easier pulling that motor than replacing that transom. Good luck.
 
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