Just wondering if there is any common things that would cause my drive bottle to keep dropping down? Drops about 1/4" every 3 weeks or so. At first I though air pocket maybe?

No visible leaks, all drive lube lines from reservoir to drive are new, with new clamps. Don't see any drive fluid in driveshaft bellows.

Any ideas?

Thanks in advance!

If its not in the bellows, then its probably leaking between the upper and lower and getting mixed with the cooling water.

So if I change the drive fluid then I would know correct? There should be water in the drive or no?

Probably not any water in the lube. If there is, the water will settle to the bottom of the drive and would come out first. It sounds like a very slight leak. The lube is probably leaking into the where the water inlet holes are. You may see some light oil streaks at the water intake holes. First thing to do is pressure test it to about 10-15# and see if it holds pressure overnight.

Pressure test the lube system?

I believe he means pressure test the gearcase. I always test to about 12lbs on Bravo's. Has anyone had the carrier out recently? If so maybe they flipped inner seal though usually major leak then since reservoir cap is made to maintain pressure. It can get caught on the large "straight" propshaft units, with out proper tool, not likely on the tapered shafts. I assume there are no visible leaks like where the reservoir passage is at the drive to gimbal mating point.

Pressure test the drive using either the upper lube vent hole or lower fill hole.

No one has had the drive apart since I have owned the boat. I had one leak earlier this year, and it was the hose between the gimbal ring and drive, I replaced that hose and the clamps, along with the hose from the bottle to transom.

We are going to be heading down to cumberland for the PR (with the boat as spectators & partiers) but I want everything to be 100% as we will be in the water Wed night through sunday.

I am going to recheck everything this weekend, and do a drive lube service, and make sure there is no water inside.

So as for pressure testing, i can just dump the drive lube, and before I fill it, reinstall the vent screw, and regulate air pressure to 12psi at the lower fill screw, and just look/listen for leaks?

Thanks for the help guys.

Check propshaft seals for fishing line. It wraps around shaft and lifts seals up.

I bet half the boats on here have leaks similiar to what you are seeing - I am one of them. I have NO Idea where it goes, but it isn't in the bilge, and the drive isn't getting water in it, so I just top it off and move on....

I would primarily be concerned if you are seeing water when you do your drive oil changes.

Hey Griff - aren't todays Merc Drive Lubes forulated so that the water "blends" with the lube so that it doesn't seperate? Not sure, just thought I remembered reading/hearing that.