Knocking/clicking noise - gimbal bearing and u-joints replaced.

[Mini hog]

My Mercruiser 5.7 with alpha gen 2 outdrive has a knocking/clicking noise that I have a really hard time to get rid of. Gimbal bearing and u-joints has been replaced but it has not solved the issue. Outdrive/engine is aligned. Engine mounts looks good.

The noise increases as I turn the steering sharp. Going straight forward there is no noise. Two mechanics has inspected the boat and listen to the noise, no one of them could tell me what is causing the noise. I also sent a question to a mechanic via his webpage and the only idea he got was to replace the coupler.

Before I pull the engine, what do you think, could it be the coupler (I assume the noise could come from worn splines)?

This has been the third season with this noise. But when I re-mount the outdrive (lower house) this spring there where no noise the first 15-20 minutes. I used a lot of grease on the drive shaft. Maybe that terminated the noise for a short while??

All ideas are welcome!

Rgds from Sweden

 

[Walt T]

Re: Knocking/clicking noise - gimbal bearing and u-joints replaced.

Remove the drive then start it. See if you still hear it.

 

[thumpar]

Re: Knocking/clicking noise - gimbal bearing and u-joints replaced.

Remove the drive then start it. See if you still hear it.

^^^ Time to isolate the problem.

 

[NHGuy]

Re: Knocking/clicking noise - gimbal bearing and u-joints replaced.

First off, welcome to the forum.
If you realigned and correctly installed everything there could be rotting stringers or transom allowing things to get out of shape. That would be really bad.
If you are comfortable that the structure of the boat is sound maybe recheck the universal joints. They can't have any play at all in them. I test them by pushing them in and out, back and forth, up and down. There can't be any play and they have to move smoothly.
Inspect the splines in the coupler end of the drive yoke, they need to have squared ends not points. Also check the splines in the coupler, same thing there. If either of the two is sharply pointed it's worn out.
My boat clicks at full lock, it's how they are. But mine doesn't click til it's almost at the steering stop. They do make high performance joints for the bigger motors, maybe give that a try. I'm getting that style next time I do mine.
Give it very little power at extreme turning angles, there's a lot of force going through that drive shaft.
Put on a rubber glove and turn the gimbal bearing by hand, it should be buttery smooth with no movement fore & aft, or up and down. Any graininess or play, replace it. Again.
That's all I got!

 

[Mini hog]

Winters over in Sweden and time to get the boat back in the water. Still want to solve the issue with the knocking/clicking noise before the boat will be used on a daily basis.
​Today the outdrive is removed from the boat. And Im planning to start it and see if the noise is there or not.I usually attach a hose with fresh water to the drive when I start the engine out of the water. How should I solve the cooling when the drive is removed? (its sea water cooled)

Also, this a picture of the coupler splines. Seems to be fine...

To summarize it:
Splines on coupler - OK
Splines on shaft - OK
U-joints - OK
Gimbal bearing - OK

 

[bspeth]

Cut the end off a hose and stuff it in the water inlet on the bell housing,water pressure will keep it cool at idle speeds.

 

[ouachitaman]

I have an Alpha 1 gen two for 12 years, bought new. It has clicked at full turn since bought brand new. Everything inspected multiple, multiple times, nothing wrong. I think that the system may allow turning just a bit beyond what the ujoints like.

 

[Mini hog]

Okay, no noise when I run the engine without the outdrive. Mounted the drive and still no noise. But the boat isn't in the water yet and Im pretty sure that the noise will be back after 10-20 minutes of cruising. The knocking/clicking noise disappeared last time the outdrive was remounted but came back after a using the boat in the water for a short period of time. And thats we I thought it could be the splines on the coupler that was damaged. And with all new grease on it it just when silent for a short while.

But to me the splines looks good. I will get the boat on the water this weekend and test it for an hour or so.

 

[Mischief Managed]

My drive clicks and rattles when I turn too. I think they all tend to do this to some extent. U-joints (even in a double cardan application) will always have velocity errors if the drive shaft and driven shaft are not parallel. The velocity error increases as the angle between the drive and driven shaft increases. The only real solution is to use a constant velocity joint. Not sure why they don't, I think one would fit. Would not have to be too big since the torque is pretty minimal right out of the engine. Look how small they are on FWD cars where the torque is huge.

 

[Mini hog]

So, case solved. It was the center socket which was slightly too big/wide. Now its replaced and no strange noise when turning. The mechanic who replaced the u joints from in the first place didnt check the center socket.
Just wanted to update the thread if someone has the same noise but it isnt solved by replacing the u joints

 

[Bondo]

So, case solved. It was the center socket which was slightly too big/wide. Now its replaced and no strange noise when turning. The mechanic who replaced the u joints from in the first place didnt check the center socket.
Just wanted to update the thread if someone has the same noise but it isnt solved by replacing the u joints

Ayuh,.... Glad to hear ya finally found the culpurt,..... Thanks for stoppin' by with the Update too,.....

 

[JoLin]

Forgive my ignorance, but what is the center socket?

 

[Bt Doctur]

the "center socket" (#36) is the piece both U joint connect to. The "wiggle joint" "constant velocity joint" etc.

 

[JeffS1]

Thank you for the great info and asking the question on center socket, was wondering same. Hoping this is my issue, tried other fixes unsuccessfully.

 

[DeepBlue2010]

Thanks for updating us, very few people take the time to do so after solving the problem. I am just curious, how the problem is the first U-Joint developed in the first place. Do you know the history of the boat? Was it working OK with you and then developed the knock?

 

[Mini hog]

Thanks for updating us, very few people take the time to do so after solving the problem. I am just curious, how the problem is the first U-Joint developed in the first place. Do you know the history of the boat? Was it working OK with you and then developed the knock?

The boat was about 10 years old when I bought it. The knocking sound was there from first day, but it was not too bad. Since I want everything to be in order and I hate the noise that occoured during every sharp turn I decided to replace the u-joints. But it didn't solve the problem and it took me 4-5 seasons before I found a mechanic who could help me.
I don't have any idea why the center socket was too big/wide. I didn't ask the mechanic =( It seems to be a very rare problem though. It should not be any problem to continue to use the boat without replacing the center socket (if you can stand the noise) But with a faulty center socket you will most likely ruin the u-joints faster than normal.