Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runabout

Hello new boating family!

I am stoked to finally be able to start enjoying some time on the water! However, I have to first get around the obstacle that is my boat. The boat itself is in fair condition; it was owned by my fiances' uncle for years, he parked it because of a phantom water leak last year and its been in his barn since. He gave it to us as a wedding present / something to have fun on this summer before I deploy to Kuwait.

I am relatively mechanically inclined, but I have no idea where to start with this...

I went through with the manual and checked things over when I got it home, everything looks good. And my curiosity prompted me to put it in the water to try to determine where the "leak" was coming from...
I he my buddy watch the engine compartment while I backed it in and it almost immediately began to take on water. I kicked on the bilge pump to remove the water while I looked for the source and it cleared out with no issue. I could not get my head around the back far enough to clearly see anything, I did notice what looked like water running down the back wall of the engine compartment, towards the middle, possibly lower.

The weird thing is after I pulled out from the dock and started motoring around almost no water was entering. I even stopped a few times to see if it would start pouring in when not moving forward and water never came in the way that it had at the dock. We stayed out for about an hour and a half and I only kicked on the pump a few times (mostly for peace of mind).

I want to fix it but have no idea where to start.... If anyone has an idea please let me know! Thank you so much for the help!!!

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

Search OMC thread for leaking bellows and see if that matches up with your leak.

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

I'll look more into the bellows. I've already checked it all over (short of pulling the vertical drive) and the seal looks like its in decent shape still.
Thanks for the tip!!

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

'87 should be a Cobra, right? If it's a Stringer, you may have a few other places to look.

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

I believe it is a Cobra, how do I verify that? And what would be the other areas to check out??

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

charles.manifold said:

I believe it is a Cobra, how do I verify that? And what would be the other areas to check out??

Click to expand...

Pull the drive and check it all out.
Bellows, rotten transom, rusted y pipe etc.
Post a pic but my guess is it is a cobra.

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

charles.manifold said:

I believe it is a Cobra, how do I verify that? And what would be the other areas to check out??

Click to expand...

If you can see a 1/4 gear on the port side of the drive, it's a Stringer. If it's got rams on both sides of the drive it's a Cobra.

You may put some water into your bilge and see if you can see it leaking down the drive (plug in, of course).

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

I will post some pictures tomorrow.
Put it in the water again today and for whatever reason it took on significantly less water than the first time; I was primarily curious to see if the leak was consistent, and it's bugging me that I can't determine whether the leak is static or operationally occurring.

I did notice today that my temp was fluctuating. The first time out it stayed right at 160, today it almost hit 180 and stayed there for a few minutes at cruising speed, then it dropped down to 130-140 at trolling speed.... That wouldn't have anything to do with the leak would it?

Thanks for the help, pictures tomorrow.

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

I should mention that "significantly less" is still quite a bit more than what should be there.... I'm not sure if I can ever expect "dry", but there is definitely water intrusion occurring.

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

For some reason I cannot insert pictures into a post...

I am fairly certain it is a cobra that I'm working with, it has the 2 hydraulic rams on the outside of the vertical drive.

I am going to attempt adding water to the bilge (plug in) and watch for where it exits. Is there an area that I should pay particular attention too?

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

Yes, sounds like a Cobra. Bellows are a first check, and it sounds like you need to have the impeller replaced.

You might try putting the plug in while you've got it on the trailer, and raising the bow up. Don't fill the boat (like you're flooding it), but fill the bilge up with a garden hose and see if you see where the leak is coming from.

If you don't have a shop manual yet, getcha' one. I don't know the Cobra drives, but someone will be along who does.

Re: Please help! New to boating and need assistance! 1987 OMC 3.0 in fiberglass runab

Yeah that was the first thing I got when my fianc?s uncle gave us the boat and tried to explain that it had a leak. I work out of manuals every day so I thought I was gonna be all set; but the manuals no use in finding the leak at its source.

Will update after some further exploration