Possible u-joint replacement, oil question

[stephentyler20]

Hi all! As usual with the new year here, my mind's starting to drift back to the boat again (no pun intended). I have the luxury of keeping my boat in a heated barn, so even though I winterized it, I hadn't gotten around to changing the gear lube yet (I did it late in the season over the summer anyway). Went down today to do it... Happy to report that the oil was as green as when it went in, and looked (superficially) flawless. The only thing I noticed on both drain plugs (I have magnet plugs in both upper and lower), is that there were some black metal bits (very very small, like dust) on each plug. Not a lot, but enough that I wiped them off with a rag. Is this fairly normal? I redid the upper gear housing last year, for what it's worth, and haven't touched the lower housing. And it's a 1988 Alpha One drive.

So at the end of last season, I was starting to hear a faint knocking sound coming from the drive. The sound was only audible at lower speeds and idle, but it was very much there. It sounded in tune with the drive shaft speed, and was definitely coming from the upper part of the drive. Is this likely to be the U-joints? If so, probably best to pull the drive and replace them right? I haven't pulled the drive yet this season, so I haven't been able to inspect them. Since I'm way too busy with school this year to work on this myself, I'd probably have to hunt down a mechanic to do this one for me... how much should I expect this to cost about?

 

[Don S]

Re: Possible u-joint replacement, oil question

That black glob on the magnets is normal.

As far as the noise, have you had the drive off lately? Could be water in the bellows causing your ujoints to go bad.

 

[stephentyler20]

Re: Possible u-joint replacement, oil question

OK thanks, I kinda thought the stuff on the magnet was normal, just wanted to make sure. For sure there were no big pieces of metal on there.

I should have mentioned - last year I also replaced the bellows and the gimbal bearing. So while there could have been some water in there from the bilge, I highly doubt either was leaking. Either way, the U-joint was looking a little rusted last year, and it's probably never been replaced.

Is that knocking sound symptomatic of the U-joint failing? Also, I noticed that there was a louder growl/knock when turning the wheel hard either direction, even with the gimbal being brand new.

 

[Don S]

Re: Possible u-joint replacement, oil question

You need to just pull the drive and look in the bellows. Even though you had the bellows replaced, all it takes is a hole in the bellows or even the big quad ring getting knocked out of place when putting the drive in, to allow water in the bellows. That is why that is done during winterization, is so you find the stuff early before it sets in water or whatever and gets worse all winter.
Pull the drive, check for water, check the ujoints by moving them, feel that the gimbal bearing is smooth, and then you will know.

 

[stephentyler20]

Re: Possible u-joint replacement, oil question

Gotcha, I will do as you say! So is it possible that water could enter from the bilge? Or that shouldn't happen? In other words, is ANY water in the bellows a bad sign?

 

[Fishermark]

Re: Possible u-joint replacement, oil question

Gotcha, I will do as you say! So is it possible that water could enter from the bilge? Or that shouldn't happen? In other words, is ANY water in the bellows a bad sign?

As you can see from the picture above, water would have to be pretty high in the bilge to get into the bellows. The hole in the picture leads to the bellows area.

Yes - ANY water in the drive bellows is a bad sign.

 

[Don S]

Re: Possible u-joint replacement, oil question

So is it possible that water could enter from the bilge?

Sure, if the water level inside the boat was deeper than the centerline of the crankshaft of the engine. Of course, if it was that deep, the starter and who knows what else would have been under water also.

 

[stephentyler20]

Re: Possible u-joint replacement, oil question

OK thanks. Not sure when I'll have time to pull the drive, but maybe sometime this week. I was hoping to build a nice stand for it, but that involves even more time!

 

[havasuboatman]

Re: Possible u-joint replacement, oil question

Sure, if the water level inside the boat was deeper than the centerline of the crankshaft of the engine. Of course, if it was that deep, the starter and who knows what else would have been under water also.

And your feet would be wet. We call that sinking.

 

[stephentyler20]

Re: Possible u-joint replacement, oil question

And your feet would be wet. We call that sinking.

Lol. Gotcha. None of that yet!