This is a followup to this thread: Leaking Bravo 1 Gear Lube

After fabricating the replacement gear lube bottle, I ran into a new problem. Before the second day of use, I noticed that the level in the resevoir was higher than the fill mark, so additional lube appeared to be in the bottle. Thinking that air trapped in the drive might have expanded pushing some of the lube back into the resevoir, I removed the prop and drained some lube. Seeing no water in the drained lube, I added lube back into the drive until it was full and sealed it back up. Even though the resevoir was 3/4 full, I decided to not try and drain it in case there was a possibility of trapped air in the drive. We then proceeded to use the boat for a day.

Today when at the ramp preparing to launch, I noticed that the bottle was completely full and had overflowed. Off came the prop and I drained fluid until it stopped flowing. We were quite happy to see clear fluid come out with no sign of water. I replaced the lower plug and removed the upper one. It was obvious that draining the lube had created a vacuum in the drive when air gasped into the hole.

PROBLEM #1 -- why did gear lube not flow from the resevoir into the drive when I drained some lube?

Since my lube pump was at home, we headed over to WM to buy a quart of lube (never use up your spare!) and another pump. I slightly overfilled the drive and after cleaning up, moved into the engine compartment to drain the excess fluid from the resevoir. Using the pump to move lube from the resevoir to a dump bottle seemed like a good way to avoid making a huge mess. I was not thrilled to find that the lube at the bottom of the resevoir was contaminated with water, but at least there was a clue to the excess lube.

PROBLEM #2 -- how is water getting into the resevoir?

My best guess is that the o-rings between the outdrive and the bell housing are in poor shape (in the previous thread, you may remember I had a problem with the one around the lube line). Exhaust gasses/water may be pressurizing the joint and forcing water into the lube line, backfilling the resevoir.

Trying to diagnose this has pointed out that I really don't know how the lube resevoir replenishes the lube, and where the check valve(s) are. The Mercruiser service manuals that I have don't seem to cover this. Anyone care to educate me?

No clue on problem #2, not sure why you have water in the reservoir but not the drive? As for problem #1, it takes FOREVER for the lube to move from the reservoir to the drive! You have this thick goo that has to travel thru a tiny hose, and if the vent cap isn't removed, the air inside the drive it displaces must come back thru the same tube as air bubbles. Even with the vent cap off it takes a long time. I figured a way around this problem last spring: small wet-dry vac. We have a 1 gallon vac, and I found that it'll suck the lube into the drive at the rate of about a quart in 15 minutes. I propped the vac hose up with some lawn chairs so that the vacuum would hold the end of the hose against the drive, over the upper vent hole. Worked like a charm, I just had to keep an eye on it when it was about full.

OK

#1 - I would suspect that the line is blocked and the reservoir cannot drain into the drive. This would explain the vacuum noise when you loosened the upper screw. I would get a fluid pump and see if you can pull oil from the reservoir via the upper plug hole. If it feels difficult to pull fluid into the drive, then I would suspect the hose that leads from reservoir to the transom plate.

#2 - I failed to see in your post, where/when you were getting water into the reservoir bottle. Anyway, perhaps water is draining over it and some is getting into the bottle. After all, didn't it used to be a water bottle in its former life?

My advice is correct #1, then monitor #2. remember that water is heavier than oil and will sink to the bottom of the bottle and should then go into the drive. At that point it sinks to the bottom of the drive, and should be the first thing that comes out when you loosen the lower plug.

FR, I see what you are saying, but we drew a pretty good vacuum on the drive, with no measurable flow of lube from the resevoir over a 10-15 minute time. And, there is no sign of water in the drive, which should have happened with the amount of water at the bottom of the resevoir. I think tpenfield is probably correct about a clog, but I wonder if it might be in the drive.

I do not see any way that much water could get into the resevoir through the cap. I have it almost all the way closed, with just a little looseness to allow air to flow (still need to drill a vent hole). We are basically talking a cup of water!

Assuming the water is coming up the hose, I don't see how it could have a clog, hence my guess that the clog is in the top of the drive. I wish I checked for bubbles in the resevoir when the engine was running. We were rushing at the end of the day yesterday, so I still need to look at the resevoir after 2-3 hours cruising and see what happened. I'll check in the morning and report back.

Quite an interesting and unexpected problem...

The resevoir is at the same level. I expected to see it filled with water again.

Go figure...

I guess I will check for water in the drive and run the boat again this weekend. It is the last trip for us, so over the winter I will go through the system and figure out what could have gone wrong.

Hey, way (grin), was just reading thru this thread, and this post by T-squared in particular:


I wonder if something as simple as your new cap could be why you had water in the reservoir?

FR, thnks for pointing out the other thread with T-Sq's comments. That helped me better understand the whole system and give me some ideas to try on mine. I may even try to incorporate the original 1-way valve into my new cap.

In any case, I do not think that the cap caused the water to be drawn into the resevoir for two reasons. First of all, the cap has been loose enough that I do not think a vacuum could have been created. Also, if there was a vacuum that sucked water into the resevoir, it would have also sucked it into the drive, but that has not been the case so far.