Mercruiser Alpha One grinding noise

Got a problem with my 130HP mercruiser Alpha One i/0,

It seems to be operating OK but making a low pitched grinding noise:

When the trim is all the way down, it makes the noise, But, when you raise the trim slightly, the noise stops. If you raise the trim too much, the noise starts again.

When you turn the wheel either right or left, it makes the noise (pretty loud, too).

When you put the boat in neutral, and do the same thing, no grinding noise, even at comparable RPM's

My theory is it's the universal joint is shot/bearings worn, and the whole thing is getting ready to go out.

How complicated is it to take off/check this part? Do you need special tools? I already have experience at trying to reinstall one of those rubber bellows on the back, which was a pain in the neck, so if the other two bellows plus rest of the assembly is similarly a nuisance, I will turn this one over to the pros and let them have at it.

Thanks, oh great forum dwellers, for your advice.

 

The very same problem!

I have a 2005 Glastron with a Alpha I... It has very low hours. Surely the U-joint and bearings couldn't be the culprit. My '99 pontoon has the same 3.0 and outdrive with many more hours and seems to be bullet proof.

Please help us! I hope, as my Dad often says, "It's probably something simple".

 

Hi pup55,

Your suspicion about the universal joint and bearings sounds plausible, given that the noise only occurs when the drive is in a position where the universal joint is misaligned. A mechanic familiar with the Alpha, given the opportunity to listen to the drive while it is running, may be able to pinpoint the cause.

Most "grinding" noises, in anything mechanical, are indicative of expensive parts being worn away. Having it repaired now will most likely be much cheaper than waiting for something to fail.

Pretty much the only way to get inside the gimbal assembly of most sterndrives, Merc or otherwise, is to take the whole drive off, including bellows, trim rams, shift linkage, etc. If you thought replacing one bellows was a pain, you might well consider the work needed to get to the driveshafts to be a form of torture.

Now, if you're going to have expensive work done on the drive, it's worth figuring out what caused it to tear itself apart in the first place. Are the interior and exterior components of the transom assembly properly aligned? Is water getting in somewhere that it shouldn't? Do you run the motor while the drive is in the tilted-up (trailering/beaching) position? (Doing so tends to wear things out very quickly- the engine should be off before moving it to the tilted-up position).

 

The noise comes from a giant bearing that supports the shaft with the universal joints. It is a ball bearing with a rounded outer rim, pressed in an aluminum carrier. It should regularly receive grease from the point on the right hand side of the gimbal housing, behind the swivel mechanism. That should keep the water away, but with a damage bellows or worn shift lever, water still reaches the bearing and destroys it.

To remove it you must take the drive off (6 nuts and the pins from the trim cylinders). Then you need something called a pull-hammer, a 2 ft long piece of steel bar, one side bent a little over 90 degrees, the other side threaded with a nut on it. A heavy piece of iron pipe freely slides over the bar.
The hook is inserted in the bearing and some quick pulls on the iron pipe move the bearing outwards.
The new bearing can be pushed into place with a piece of wood and a hammer.

Replacing the bellows is a nasty job anyhow, but if your drive is an Alpha-1 2nd generation it cannot be done without a special tool to push the expander ring into place. More details can be found on www.sterndrives.com