u-joint noise: how much is normal? Also, alternator 1 vs 3 wire

[jesse_boston]

At idle, with the outdrive all the way down and steering straight, I can hear a slight knock. It almost sounds like the noise an old car engine I used to have made when it had spun a bearing, but much quieter. Above 800 or 900 RPM it settles out, no more knock.
But, if I turn hard to port or starboard, I can definitely hear it again, at any RPM.

I'm pretty sure this is the u-joints. How much noise is normal?
I could try to get an audio recording of it next time I have the engine running...
Am I risking catastrophic damage if I run it this way for the next few trips out, if I don't get into it when turning?

If a joint blows, will I be looking at transom repair, new gimbal housing, etc etc, or just a tow?

I will rebuild the u-joints this winter, would like to avoid doing it on a good boating day if I can wait.

Alternator: Mine is shot, battery worked its way down to 12.3 from 12.6 in a 5 hours of boating... not bad with the tunes going and the fridge running.

Is there a reason I should stay with a 3-wire alternator, instead of switching to 1-wire? Amazon can have a 1-wire 110 amp DB electrical alternator to me tomorrow, 3-wire end of the week if I'm lucky, next week if I'm not.
This is a 1995 5.7 mercruiser alpha 1 carb with a mechanical fuel pump, thunderbolt 4 ignition.

 

[Scott Danforth]

pull the drive and look at the u-joints, gimbal and bellows


I dont recommend a 1-wire alternator on a boat.

the 3-wire will start charging immediately. the 1-wire requires the RPM's to be brought up high enough to excite.

so if you troll a lot or idle a lot, you may not be charging.

 

[Rick Stephens]

Pulling a drive and looking is a 10 minute activity. Avoiding it takes all day.

 

[Bt Doctur]

Examining it now before it explodes is the better approach

 

[Bondo]

If a joint blows, will I be looking at transom repair, new gimbal housing, etc etc, or just a tow?

Ayuh,...... No u-joint noise is normal,......

It's possible that blowin' one could leave ya lookin' at the surface of the water,....................Above ya,.......

 

[jesse_boston]

Alternator: Installed a 3-wire 65 amp. The factory harness wiring is very small gauge, I'm surprised it is enough for that much. Will likely run a new set of wires straight to the battery over the winter.

u-joints: i kinda don't know where to start. I can pull the outdrive (though last time it took a lot of swearing to get it back on the boat), but what am I looking for? Am I checking if something has extra play? Listening to things? Do I want to clean off all the old grease? I ended up *covered* in grease last time I was in there.
rebuilding: do i just follow the video I saw where a guy just put the joint on top of a socket and hammered away at the grease cap with another socket until it pushes out the other side? I don't own a press.

Thanks as always

 

[Rick Stephens]

With your symptoms, you need to replace the u-joints. You can take it to someone, spend a few Ben's on it. Or pick up a Harbor Freight ball joint press, or something similar, and figure out how to push them in and out for yourself. I would probably not recommend hammering them in and out. Problem is you end up 'upgrading' things that work best left original, like the straight machined holes the bearing caps press into. It is not easy pressing u-joints on a Merc. The damn spanner nut makes access very limited. I had to file a teeny bit off one of the nut tabs the first time I did one an an original Alpha 1. It can be done, just gotta figure out how to apply the pressure.

Different boats, especially those with swim decks, can be tough to access the drive when sliding it on and off. I could probably take my drive off and reinstall it in 20 minutes without breaking a sweat. But I've done a lot of them and know what tools to grab and how to position the boat for ease of access. I do lightly coat everything that is bare metal with 2-4-C grease when installing. But I can wipe it off as I go and reapply as I install. Grease is grease, wear gloves if you don't like it on your hands. And you must have an alignment bar and check alignment before reinstalling - every time!