Drive lube

MarkB

Hello all. Today after a little run out for fishing, I checked my fluids after returning to my slip. Everything was great except for my drive lube. The level was at the ADD line. Last time I checked it was full, and there was only two outings between this time including today's. 

What  could have caused the level to drop that much. I know there could be 'burping' but I've never seen it drop by that much. 

Admittedly it's only the 4th time I had it out since I put her in the water this year. So it could be some air lock due to the last service. 

Should I check something? 

Black_Diamond

Probably a burp. Keep an eye on it, if ot keeps consuming oil you'll need to have the seals looked at. 

MarkB

OK thanks. I also spoke to my (amazing) mechanic. He isn't too stressed also said to keep an eye on it. No water getting back in as the fluid is still clean and clear, so the worst it can be is a leak at the prop. Don't see any slicks whatsoever, so most likely a very big burp. 

Hopefully going out tomorrow so I will check on it. 

Michael T

After it has sat for a bit look to see if there is any oil sheen on the water ( there won't be much so you will have to look carefully)  there are a couple of O rings on drives that can leak. If you fill it up and it goes down over a week that is a likely culprit. MT

MarkB

I don't think the level drops while the boat is sitting. It looks like it drops only when the boat is running, but I have to check that.  Will do tonight. 

I did take her out again last night - went out for about 3 hours. The reservoir level fell about 3/4".  Had to top it up again.  My guess is that it is leaking while the engine is engaged, probably a prop shaft seal.  I should probably start it up and engage it under slight load at the slip and see if I can observe a slick.

Michael T

Yes, Mark if it is an oil leak it will leak underway but you probably won't be able to see it. When it sits for a few minutes (30 or so ) in your slip maybe you will see a very slight sheen from the leak that happened underway. That happemed to me with a 4.3LX Alpha l combination. It was driving us nuts and I thought it was going to be costly until the Admiral saw a slight sheen on the water, while we were putting the canvas on after about 30 minutes. It was an O ring in the drive and was real cheap to fix. MT

MarkB

OK thanks MT.  I called Mercruiser and this is all under warranty (thank goodness I got the 3 year extended Platinum Coverage). The main thing is that Mercruiser don't think I need to pull the boat right away, no immediate danger to anything, so it's just a matter of keeping the lube topped up, until I pull the boat in late September. That's of course unless it starts accelerating consumption to the point where it is unmanageable - so hopefully things stay put.

Michael T

Great news Mark. That's what my tech said too - but the frigin' leak got worse and worse. I was topping up the resevoir every second trip. When he showed me the O ring I asked how a little bu**er like that could loose so much oil. He replied it's uneder pressure. At least it's a cheap fix. Two thumbs up for your smarts to purchase an extended warranty Mark! :-) MT

TikiHut2

Prop wash of any consequence would probably dissipate the tiny amount leaking at near idle. If it's not too much trouble I'd try to let it set overnight and do a quick lift at the marina or at a friendly dock and have a screwdriver and small clean container ready to sample check the drive oil at the foot. If water gets in there it's a really painful $$ experience. 

I recently pulled the top cap off my OD and found that the top vent plug is about a pint down from filling the drive completely so a recent oil change will probably burp more air than you'd think. Hope that's all it is. 

Below, A nice clean sample with no metal or milky water contamination. Slight fuzz on the magnetic plugs is normal but be sure to check the top and bottom plugs. Love the symmetry of those bearing sets... especially when they are all where they belong.

Mike

MarkB

Tiki, not sure if it makes a difference, but I'm in fresh water, so I'm not as concerned about corrosion. I asked the Mercruiser Customer Rep if water getting in is a problem, and he said that the Mercury High Performance Gear Lube was made to work in water, so he didn't seem to be too concerned, and just asked me to keep observing it. If there's further damage, it's all on record, so the warranty will cover it all! LOL.  OK, I don't want any further damage, but including MT's tech, there's 3 sources saying it should be okay.

I basically have 1 more trip out before I'm in Florida, then about 3 or 4 outings at most before we pull the boat in September.

Now, I don't want to brush off what you're saying. If water gets in (freshwater) what would the concern be (or the significant damage that can happen)?

 

TikiHut2

Water of any kind just isn't what a gearset likes to run into when it's under load. There's nothing magical about a drive oil that'll neutralize the lack of lubricity that water has. 

Any positive pressure created by the heat generated from running should force oil out.... but what happens as the drive cools being submerged? 

That said I've had a dozen lower units that I discovered had slightly milky oil and needed a seal kit and there was no lasting damage if caught quickly.... so maybe there is some magic in that oil.   After all the drive issues we've seen lately I'm probably just being a drama queen. 

Post what you find. It'll be interesting to hear. Mike

MarkB

For sure Mike. We will probably need to wait to October to hear the outcome. In the meantime I'm hoping that it's just that my drive has a bad case of gas, and all this burping is going to stop soon.  Burping is better than barfing gear lube. LOL.

Black_Diamond

++ from Tiki: but again there is no oil that can take in water and still perform, the water will displace the oil under load and you'll get metal to metal contact and then the associated wear, corossion, etc.  The EP additives will help over a plain R&O oil but it is not magic against water.  If it is an oil seal (and/or damged seal surface) it will keep getting worse.  Unless the seal is badly damaged, they tend to leak very little at rest and being underwater you have the external water pressure to balance the oil in the drive, once you start spinning the shaft is when the oil starts leaving due to pressure in the drive (warming oil) and the seal can actually pump oil out (or even water in). 

MarkB

I'm assuming because I have drive lube dropping in the reservoir, oil is getting out, rather than water getting in? 

Black_Diamond

That would be reasonable to asusme...but things can mix as the unit cools off and it can suck in water..probably not much but it happens.

Hopefully it is just clearing air..you can use a few oz (or several ml for your metric folks!) easily.

MarkB

Well, I think I added a little more than 1/3 quart on Saturday after 2 trips of 5 hours each (10 hours total), and then maybe about 1/6 quart on Sunday after a 3 hour trip.  So, probably a little more than  1/2 quart in total after 13 hours. 

But those hours are not tough on the engine. Basically I go out to my fishing spot at 4100 rpm, 30 mph which takes 15 to 30 minutes to get to, then troll for 2 - 4 hours at around 600 - 800 rpm (control speed at 2.5 to 3.0 mph).  Then back to the slip another 15 to 30 minutes planning at 4100 rpm, 30 mph.

If some water gets in, will it basically be pushed out of the seal as the oil heats up? Can damage be caused during this time frame, or is it pretty short in duration, and so not really much to worry about?

TikiHut2

That's not a surprising amount of oil if there'd been an oil change in the last few hours. It's probably nothing but a gas bubble....... but I'd still say if it was me I'd do a quick check if it wasn't too hard. Good luck.

Wish I had my trailer close to you and we'd know in 90sec...... but that's a heck of a commute. Cya, Mike

pvantienen

I recently had my motor rebuilt and some maintenance on the lower end. I have been keeping an eye on the fluid levels as usual. I too noticed my gear lube dropped down, it's now in between the add and fill lines. I am assuming a burp as well. Can I just top up the reservoir?

Michael T

Yes, in fact you should immediately (before another outing) top up the resevoir AND continue to keep an eye on it. MT

MarkB

Yes P. Top it up to the full line. Please make sure you use the right fluid. If it is drive lube, then the Mercury High Performance Gear Lube is what you want to use (assuming you have a mercruiser engine). 

@TikiHut2 The fluids were changed at the begging of the season, end of April. Since then I had the boat out 5 times, including the last 3 outtings discussed above. 1st outing I checked, no fluid change. 2nd outing I checked, had to add a very minor amount of drive lube - probably 1/8th quart.  Next check was after outing 4 (so 3 and 4 combined), and had to add over 1/3rd quart. 5th outing, last night, 1/6 quart. On average each trip is between 3 and 6 hours - but as indicated, most of this is trolling at a speed between 600 and 800 rpm.

Thanks for all the advice. And Tiki maybe I should take my boat to your trailer. LOL. I don't know if the seal would last though!

MarkB

OK so I went to the boat tonight, the reservoir level is about the same as when I filled it last night. I ran the engine at the slip, no sheen. I engaged the prop at idle speed forward. No sheen. 

So I don't think this is happening at slow speeds. 

I raised the drive to have a look, and everything appears normal. 

Praying to the good Lord above that it was just air. 

youstolemybeer

I wanna know why none of the outdrives I have ever opened up NEVER looked that pretty. Mine usually would be rusty or missing chunks of bearing (on a good day).

Im jealous

I

TikiHut2

Great news Mark, now where's all that fish we've been hearing about?

lmao beer, Sounds like yours were toast by the time you got in there. Maybe I'm just crazy for opening up a perfectly fine OD to see what's in there and make sure everything is playing nicely....Inquiring minds want to know. It's the kind of art/sculpture that my warped mind appreciates....... when they're behaving.

Actually the drive guy from All American ODs asked me to pull the top off to look for metal on the top bearing sets. He said that's a spot where loose parts will settle if it's starting to screw up. It's only 6 bolts to easily make sure all is well.

Mike

Black_Diamond

Beer: if you are seeing rust..you have water intrusion, changing annually or at least checking an oil sample will tell you if things are going well.  The water can lead to the degradation of everything.  Add that I bet most people only open a drive when they think something is wrong...

aero3113

At the beginning of last season I had my drive serviced (water pump re-seal and pressure test). The whole season I kept having to top off the reservoir. This season i only had to add a little after my first outing, it's been at the full mark ever since.

TikiHut2

Aero, Seems like you had your share of oil leaking.... from your oil pan last season..... yikes. You've paid your dues. Glad that OD is tight.

Thanks to your post on that oil pan condensation I caught mine in time. Owe you one.

aero3113

Tiki, that's what this forum is all about. You don't owe me anything! Well maybe a beer or three if we ever cross paths, LoL!

Dan4754

I found this thread and it has lessened my concerns.
I had major work done on my '05 FL 250 in 2010 and put in storage until fall of last year. One of the repairs was replacing the stern drive.
Last fall I had the shop de-winterize it and put it back in storage until last week.

After running to the fuel dock (about ten minutes) and fueling (another ten minutes) I started the motor and headed back to the slip
The alarm started almost immediately and I have since determined that the drive lube reservoir is low.
The air burp is a hopeful reason for this and I will be adding and checking today.

My concern is the color of the existing fluid. It is dark and brown, not green and clear.
Seems to me that the fluid should have been replaced when the drive was replaced and should look pretty new.
The bottle of Quicksilver "high performance" gear lube says to not mix with "premium" gear lube.
Do you think the discoloration is a concern?

The boat has a total of 120 hours on it.

craigswardmtb

That sounds strange to me.  If using Merc/quicksilver lube it should be bluish-green.  I would play it safe and drain and fill.  Worth the piece of mind.

MarkB

I think it should be greenish blue. Having said that I am told there is no way for drive lube to be contaminated with anything all the way back to the reservoir. If you have a leak, it leaks into the water, not the other way around, except for some water perhaps getting into the lower end of the drive. So did they perhaps put a different kind of drive fluid into the reservoir. I would contact the mechanic to find out.

212rowboat

brown?  like- hardly creamed coffee brown or like straight coffee?  water intrusion will turn it to look like chocolate milk when it's bad enough. 

burping is normal- and expected after servicing.  it's been my experience that a full fill reservoir will enter the drives after a service, even after pushing oil from the bottom to the vent confidently.  

the thing about these drives, is that they are double sealed.  the exterior seals purpose it to stop water intrusion.. the inner seals purpose is to trap oil from escaping.. that leaves a void between them that can fill with either water, or oil, depending on which is leaking.  

if it continues to be a concern, and while high and dry, loosen a clamp on the bellow and pry the ring of the bellow up just a touch... if oil escapes, your inner seals are not doing their jobs.. if water escapes, the outer seal isn't doing it's job.. if chocolate milk escapes, you've got problems you need to address right now instead of kicking that can down the calendar to 'end of season'.