my sterndrive is growling at me

[mtfoyre]

I recently bought a 1968 Thompson 21' cuddy with a model 1967 OMC SternDrive and noticed something this weekend that hadn't happened before:

I had the boat at home just to run through some things before taking it out the next morning. When I started the motor up I almost immediately noticed a "growling" noise that seemed to come from the upper portion of the sterndrive.

I noticed that both ball gears look sheared a little as if it had been ran with the drive lifted up (that's a no-no, right?).

Also, I checked the BRP Parts Catalog I found on BoaterEd (great help, BTW) and I would guess that there are problems with the gears and/or bearings related to the following parts:

DRIVESHAFT & BALL GEAR
PINION GEAR & BEARING
SHAFT AND BEARING

Now, I'm fairly mechanically inclined but am new to boats. It seems that there are only four bolts holding the entire assembly to the back of the boat. I would imagine with some strong help and attention to detail we could pull the sterndrive off, get at the parts and have it mounted back up relatively quickly. Am I correct?

One last thing...there is an electrical wire running through the back of the boat down into the drive. It doesn't seem to have any slack on it. I'm sure I'll need to unhook it so as not to rip it out, but what is it for? Is the "transmission" simply electric and this is where the signal to switch in/out of gear comes from?

I'm new and may get some of the terms wrong. I appreciate any advice I can get.

 

[WillyBWright]

Re: my sterndrive is growling at me

Those are the shift wires. The drive is only held on with those 4 bolts. You have to be careful of the wire and it's been so long that I've forgotten how it attaches. Go to your public library. I'll bet they have one of the aftermarket manuals. You can also get them from iboats.

The ball gears are either growling because they are badly worn, or they're out of time. They need to mesh with the same teeth all the time. If the drive is taken off, it's imperative to mark the ball gears so that they get back together the way they came apart. Running at tilt isn't much of a problem because it will drop down if there is significant thrust (load).

If the ball gears are more than half worn, they need to be replaced. I believe yours has the ball gear as part of the shaft thru the transom. I don't know if you can still get them. Newer configurations are still available.

There are four places for gearlube. The intermediate housing (thru the transom) needs regular gearlube. So does the upper gearcase and the tilt clutch. The lower gearcase gets a special gearlube called Premium Blend or Type C.

 

[WillyBWright]

Re: my sterndrive is growling at me

Okay, It's starting to come back. The wires are connected just inside the transom with connectors in a sleeve you slide up the wires to detach. A bit of WD-4o helps with that. With the drive tilted all the way up, you'll see the wire held in place with a hook secured by a bolt. Remove that. Disconnect the wire inside the transom, tie a string to the end, and gently pull the wire from the outside. Greasing that wire helps a bunch when putting things back together. You'll be tempted, but don't use silicone sealer when you put that wire back in. You may need to get apart again sometime.

 

[mtfoyre]

Re: my sterndrive is growling at me

Thanks for the info so far, WillyBWright.

I should mention I was told on BoaterEd to check my gimble bearing. I have a confession...I don't know what that is. In fact, it almost sounds made up but I'm sure it isn't.

Just so you know I'm not sure that the problem is from the ball gears. They aren't worn halfway...maybe 1/5 at most.

I hope it's simply an issue of low lubricant. When I bring the boat back to the house this weekend I'll verify all the fluid levels.

 

[DHPMARINE]

Re: my sterndrive is growling at me

Very seldom does oil a growling noise solve !!

But best of luck ! !

DHP

 

[Purduebarry]

Re: my sterndrive is growling at me

Sorry MT, Gimbal bearings are real, muffler bearings are not but that's a different story. The OMC drive should be pulled each season to lubrictate the U-joints and Gimbal bearings. Depending on your model there is a nipple which allows you to lubricate the gimbal from the outside of the drive while still attached. This is on the upper starboard side of the outdrive but the business end (inside the drive) must be turned the right direction to lube properly. Bottom line, pulling the drive is routine matenaince and often overlooked. Once you get the drive pulled you'll know much better what's going on in there. Also the drive/motor must be properly aligned when it all goes back together. This sounds worse than it is unless they find some problems (water, worn parts, etc.) . Should only run about $150 for the service, more if parts are needed.

 

[mtfoyre]

Re: my sterndrive is growling at me

Very seldom does oil a growling noise solve !!

But best of luck ! !

DHP

:/ I know....but I'm hoping!

Thanks PurdueBarry.