Bad Gimbal Bearing / U-Joints?

[Agimax]

So i bought a used boat 1985 Century Bronco I w/ 3.0 mercruiser Alpha I Outdrive. Tuned up motor (though carb needs rebuilt due to rough and sporatic idle), removed lower end on outdrive and replaced whole water impeller system, put together 3 times (simple rookie mistakes) and finally filled with fluid (from bottom up with handpump) and then pressure tested to almost 35 psi. No problems other than vibration in whole boat while idling, took to lake about 4-5 times and ran like a champ. However, we have had a drought this year and like a rookie ran with the outdrive up farther than i should when pulling to the boat dock, cause it would start to hit bottom if i didn't. Still no problems UNTIL i took it on a long trip to Michigan and ran the boat HARD wide open for many hours. Ran around 4400 rpm at around 37 mph and I turned very sharply, then back straight at the end of the day and as i was backing off the throttle the outdrive started Randomly 'banging' very loudly like someone was hitting it with a sledgehammer. I backed to neutral and the sound was still randomly going on, so i shut it off and checked around the unit couldnt see or feel anything and checked the prop would lock as supposed to in and out of gears with engine off using shifter. At that point i tried to start and engine would start, the banging would randomly happen and as soon as i touched the throttle or put it in gear, the motor would abruptly die. I pulled the whole outdrive off the back and it was very hard to pull the unit off the last couple inches. I got the unit off and there was some (maybe a cup) of water in the u-joint bellow and slight rust coloration on the shaft and u-joints. The gimble bearing was replaced (supposedly) 3 years ago. I could see the corrosion was coming from the shift cable area and also around the water intake tube ring (lots of corrosion and crud). The lower end unit looked great when i had it appart before the issue and can turn the driveshaft by hand and make everything function in fwd, rev & neutral. There is slight slop trying to turn the driveshaft (inside the unit-not the driveshaft slop) to make the prop spin, but not much.

Sorry for the long post, but needed to give history!

My real questions:

The gimble bearing seems like it is rougher spinning than it should be, so i plan on replacing that, plus the vibration the boat had always at idle but lessened the faster you went.

The U-Joints even though they aren't so tight that the joints hang by themselves, have NO slack in them at all, still have white grease leftover from the last time the grease fitting was used. The U-Joints move super freely and i mean with little effort you can move it around without restriction, but can't find any information online of how to test to see if they are bad, as i said NO Play in anything u-joint related. I don't want to replace them just because if they are still good. I am not comfortable pressing them out and even less about removing the main fork out of the unit.

I am getting ready to order bellows kit, gimble bearings, alignment tool, installation tool, gaskets and all.
Do i need to get a new cable? It shifts fine, but appears the leak was from the place the cable fitting goes into.
Will replacing all of the bellows get rid of the leak around the shift cable?

There are no nicks inside the gimble housing or signs that there was 'banging' going on in there.

Again, sorry for the long post better to have too much than too little.....

 

[slicksboat]

Re: Bad Gimbal Bearing / U-Joints?

you need to fire engine up with drive off just to see if noise is gone if your worried about temp take a junk water hose cut the end off and use eletrical tape to make hose fit tightly in the hole that the water goes thru on the gimble housing after your test to make sure is not the engine also you need to check gap in points inside the distributer that has alot to do with firing if to small of gap youll get a weaker spark to fire them pistions and a carb kit will deffinatly do justice but i can give you the walk down of the carb if youd like cause i got inside info on the carb now the banging may come from running rich with weak spark its a its called 4 banger for a reason but it does balance out and pur like a kitty if you get the fuel and spark right

 

[ktbarrentine]

Re: Bad Gimbal Bearing / U-Joints?

Quite a long post, with some issues to individually comment on...
First.... You DONT pressure test the Outdrive with oil in it, and second, you only pressure test it to 15 PSI max. Otherwise you can/will blow out seals. Next, boats should not be run "hard wide open for many hours".
Next....you shouldnt have any water in the drive (u-joint bellows)....Did you glue the Outdrive nose-gasket in place when you installed the drive? What does the nose gasket look like after you pulled the drive? You indicated that it "appears the leak was from the place the cable fitting goes into" a leak in that area (from the shift cable bellows) will not cause leakage into the drive bellows. It will, however, leak into your shift cable and into the boat. You should give a really close inspection of the drive bellows. You can replace all the bellows, but it may end up that youre replacing parts that dont yet need replacing. depending on age, though, it may not be a bad idea.
IMHO...you need to drain the outdrive oil, check it for metal, and then you might want to do an informational pressure test (at < or = to 15 PSI) just to make sure the noises you heard arent internal to the drive and may have caused a seal or two to have problems. The difficulty in pulling the drive off the last couple inches sure sounds alignment related and/or you may a coupler that is about to give up the ghost. In any event, you've got an alignment tool coming (good) as it is always the best idea to check alignment anytime you have the drive off.
Also....how was your water temp during all these issues. Just want to make sure your impeller is holding up under all this.
Lastly, although not recommended, you can (as quite a few boaters can attest to) run your drive for short periods at idle (like when docking like you did) with it up past the upper trim limit. just dont make it a habit, or run it above idle like that. Some guys have to do this when traversing very shallow areas so they don't drag their drive through the sand.
Good luck and keep us posted on what else you find.
KB