The best way to pressure check the system is to buy an extra drive oil reservoir cap. Drill and install a barbed fitting into the cap and slip the hose from a small pressure pump onto the fitting. Now pump up the whole system from inside the boat at the reservoir. About 5 - 7 lbs. will do it and let it sit overnight. The next day you will see where the oil was leaking from. Either inside the boat or on your garage floor!
I would guess that it is leaking into the u-joint bellows and then inside the boat through the vent hole in the transom.
Dennis Moore
Mercruiser Master Tech

on mine the driveshaft yoke was a bit worn and had slight rust spots causing a slight leak

Ditto on the drive lube bottle.

I freaked to see oil in my bildge. My mechanic traced it back to the port bottle.

Good luck.

Jeff

My bottles were cracked as well. It was the easiest oil leak I have ever fixed!

Steve

I did notice fluid from what I believe to be the power trim. See photos. This bolt took five complete turns to tighten and the bolt next to it took one turn.

So it seams that I have two leaks, One drive oil leak inside the boat (not sure where) and one power trim outside the boat. See photo.

Does this seam right?

After look at the some more something does not seam right to me. Why would I have oil on the Mercathode Assembly?

Just for yucks and out of curiousity, is there a checkball and valve on your Bravo? When the drive is pulled from the boat, you have to ensure the ball or checkvalve hasn't fallen out. Passing along what happened to me a few years ago.

In my case, the only time that I let a mechanic service my drives, he didn't notice the ball and valve had fallen to the ground when he pulled the drive. The idiot then put the drive back on the boat, filled it to the venthole from the bottom, and then poured lube into the reservoir bottle. Had he filled the drive and the bottle completely from the bottom the way it should be done, he would have noticed the disconnect. No lube would have made it to the bottle because the mechanism was missing. The drive leaked every so lightly, and some down onto the mercathode.

Any gear lube in my bilge has always been from cracked bottles, very hard to see sometimes. I've been through 3 sets in 13 years, just now moved over to the new plastic square bottle.

Well I took the boat back to the dealer to fix the drive leak and Dennis Moore was correct the drive was leaking from the U-joint assembly.

They replaced the entire u-joint assembly and had me back in the water in two days. All work was covered under my extended warranty.

Re: Drive Lube Leak
 

Well after some 50 hours or running between end of last year and beginning of this year I have a drive oil leak again. This time the extended warranty is expired and boat is now in rack storage. Oil is leaking into bilge with no signs of oil outside the boat or milky oil in the bottle. Time to stand on my head and find leak, I'm hopping it's the bottle or hose connecting the bottle to transom

Re: Drive Lube Leak
 

bc,
if this is an XR drive, they have a tendency to push the seal out of the retainer. There is a kit to replace the retainer and seal that fixes the problem. Do the presure test that Dennis talked about. That will find the leak...

Dick
Good luck!