OMC Cobra growling noise

[whickety2007]

I have a 1989 Seaswirl runabout with the OMC 4.3 liter, and Cobra drive.
Last year I rebuilt the shortblock after a main bearing went. I had the machine work done, reassembled the engine, and had my local marine shop install it.
They had the drive off, and I assume, checked the gimbal alignment before reinstalling it. The engine has about 80 trouble free hours on it now.
The problem is that when the drive is trimmed up (anything other than almost
all the way down) it makes a light growling noise, and has a slight vibration.
I'm sure the Gimbal bearing is the original, as are the u-joints, so I suspect it is one of the two. I puchased a service kit, that has a new bearing, u-joints, and gaskets, and am going to pull the drive to install them.
If I press out the u-joint closest to the drive first this disconnects the shaft from the drive. So can I use the shaft itself as an alignment tool to align the new gimbal bearing, and make any motor mount adjustment I need?
Thanks,
Dan

 

[Bondo]

Re: OMC Cobra growling noise

So can I use the shaft itself as an alignment tool to align the new gimbal bearing, and make any motor mount adjustment I need?

Nope,.....

An Input Shaft will Not be a workable substitute for an actual Alignment Bar.....

Unless your hull is rotting away under, or behind the motor,+ it's mounts,...
It's probably still in alignment,... Provided the other guys actually Did align it......

 

[whickety2007]

Re: OMC Cobra growling noise

Well, the mounting points seem as solid as can be, so I'm sure the motor hasn't moved. I'll slap the new bearing, and u-joints in this weekend...see if the noise goes away.

Hey Bond-o this all started up your way a few weeks back I rented a place up
on mud bay, just around the corner from you. Good fishing up there!
Was running it pretty hard against that big lake Ontario swell. A little to big for
my 19 footer. Too many unmarked shoals sticking out...last year I pulverized a prop now I'm too chicken to get in near anything.
Thanks much.

 

[Bondo]

Re: OMC Cobra growling noise

Ayuh,....

If you think the bottom is alittle Boney here on the Pond,....

It's a Good thing you didn't go around the corner to the Big Creek,....

The St. Lawrence is Full of hidden islands,...
Well,.. Rocks actually, that Would be islands if the water was a few inches lower,....
If the water was just slightly lower,... It would be known as the 10,000 Islands rather than just the 1000 Islands area....

I'm Glad you enjoyed the trip,... I just Love living here.....

 

[sea wolf]

Re: OMC Cobra growling noise

Hey Bond-o, snowin up there yet? Just kidding. A buddy of mine used to slip his boat at French's Marina in Clayton. We used to make the run to Kingston, Ont. & back with a stop for a few cold ones in Gananoque {sp}. The good 'ol days. Yea, the river is beautiful, but you better know where you're going.

 

[Bondo]

Re: OMC Cobra growling noise

Hey Bond-o, snowin up there yet?

Nope,... But it Could be any day now.......

I know French Creek Marina owned by old Wilbur Wahl,+ there's French Bay Marina, owned by Jeremy Kellogg,....
I don't know that would call either of the men, Close Friends,..
but I do know them kinda well....
They both run a couple of the Better marinas in the area....

 

[sea wolf]

Re: OMC Cobra growling noise

Yea, I met 'ol Wilbur once. Kinda ornery if memory serves me right. Nice marina though.

 

[Bondo]

Re: OMC Cobra growling noise

Kinda ornery if memory serves me right.

Ayuh,... Thats a Polite way of putting it,......

I guess ole Wibur,+ I have abit in Common,......

 

[whickety1]

Re: OMC Cobra growling noise

Just a little follow up.
I installed the new gimbal bearing and u-joints today. It took me much longer than I expected, but hey I saved myself shelling out some buck for labor!
The old u-joints looked perfect actually. When the material around the needles was inspected I found that all of the were still looking brand new. I thought maybe the marina replaced them last year when I had my new engine installed , and they put the drive back on, but could not find them on the receipt for the work. even had fresh green grease hanging from the grease nipples.
I rented a nice slide hammer setup from the auto parts store, and made quick work of pulling the old bearing (which also felt perfect to the touch, and spun
very smoothly before I pulled it). I've read in many posts that just reaching in and "feeling" the bearing spin with no rough spots is all you have to do. No no
I don't think so!
I reinstalled the drive, only after spending an hour cleaning up the gasket surface on the drive itself and the pivot housing. The marina had installed some serious gasket adhesive, and 2, thats right, 2 gaskets ( no it didn't split)
There was also 2 rubber rings fit into the grove around the water intake on the pivot housing! Its a wonder it didn't leak. The bellows had no sign of water in it, and looked and felt nice and supple, so I left it alone.
Threw the muffs on, started it up, problem solved!! The drive now travels up and down, left to right with no sounds whatsoever smooth as can be.
Bond-o, I guess the alignment is right...she slide right back in with plenty of grease.
Thanks for all of your help.

 

[whickety2007]

Re: OMC Cobra growling noise

Well I out on the water today, and it ran fine. Ran it about 30 mins down the lake, and back. It still has a slight vibration at slower speeds, and I do hear some noise when trimmed almost all the way up. But it is MUCH better. I would suspect this to be normal, as the u-joints are just stressed.
I was trying to think of what changed when this vibe started, and I forgot that I
nicked the bottom, while in some unfamiliar water (bond-o's neck of the woods).
This aluminum prop is only a season or two old, and still looked perfect.
Now when I say nicked the bottom, I mean I barly felt it, and all three blades took just a little scuff. basically knock the paint off. Could this knock the balance off? I would think it would have some flexibility.
Any other thoughts on this slight vibration?
Should I just live with it?

 

[sea wolf]

Re: OMC Cobra growling noise

Put your spare prop on & see if the vibration goes away or not. If it does, take the ss one to a shop for a rebuild/rebalance.

 

[whickety2007]

Re: OMC Cobra growling noise

Thanks for the reply. Would love to try my spare prop, but I don't own one.
I should have my old chewed up one repaired. Most of my boating is done in the finger lakes in central N.Y. so there are very few hazards.
I have 2 neighbors with mercs... one with a force 90 outboard, I could see if they fit, but I don't think so.
The thing that gets me, is that the audible growling while trimmed up is now much better, but the vibe is still there. I ran it for about an hour yesterday, down the lake, but there was a ton of cross-chop with all of the boat traffic out there. It was kinda hard to feel for the vibration at higher speeds. It's definitely
there at 2000 rpm's and below.
Thoughts??