Just how critical is a bit of water in gearcase oil?

[Tinkerer]

I know the question reveals my ignorance, but if you've got only a little bit of water in there there's still a lot of lubrication, although obviously the oil isn't going to work the same as if it was pure.<br /><br />British Seagull outboards actually relied on water entering to form a water / oil emulsion. There was something wrong with it if it didn't have water in it. So at least one motor could handle it. Admittedly it was 140 grade oil, so there was a bit of scope for changed viscosity compared with modern oils.<br /><br />Engine oil changes in cars with dilution from fuel blow by, although it's probably nothing nowadays compared with 40 years ago, so they can handle a bit of dilution as well. I don't know that milky oil in an auto crankcase matters all that much in service (in the old days plenty of cars ran like it for ages if the water was kept up to them) except it indicates a water leak somewhere which might be costly to fix and which might cook the motor if the water leak isn't fixed. Auto crankcase oil would seem to be working in a harsher heat and lubrication environment than a marine gearcase surrounded by cold water with no combustion in it.<br /><br />Why is a little bit of water so bad in marine gearcases?

 

[rodbolt]

Re: Just how critical is a bit of water in gearcase oil?

how bad is a touch of rust on a bearing how bad is a touch of rust on a surfaced hardend gear face?

 

[Tinkerer]

Re: Just how critical is a bit of water in gearcase oil?

Originally posted by rodbolt:<br /> how bad is a touch of rust on a bearing how bad is a touch of rust on a surfaced hardend gear face?

So it's the corrosion that's the problem, not the lubrication?

 

[Tinkerer]

Re: Just how critical is a bit of water in gearcase oil?

But if it's the corrosion then what's the difference between the metal in the British Seagulls, plenty of which are still happily in service after 50 years of salt water in the gearcase, and other motors? Cheaper production?

 

[Bluefish]

Re: Just how critical is a bit of water in gearcase oil?

In a perfect world, no water would be great that said I have been living with a prop seal that lets water in every season for the last 8 years got tiered of changing it every year only to least three mouths in to the season. It only takes a few drops of water to turn the oil milky in that blender of an out drive; you need to determine the condition of the oil and the risk you want to take? Do change oil and run before boat is layed up for any length of time. Do a pressure and vacuum test to try to repair problem and check your orings on the plugs many times their the problem. Were goner start one with this

 

[llfish]

Re: Just how critical is a bit of water in gearcase oil?

How do you measure a little bit of water in a gear case full of oil? Correcting the problem could save you a little bit of trouble and a lot of cash down the road. This motor is trying to tell you something.

 

[BillP]

Re: Just how critical is a bit of water in gearcase oil?

Other than corrosion, a "little" water won't do much except wear parts faster. How many hrs it takes off gear life is a guess. 1940 SeaKings (made by Merc and same as a Merc K1) had an open hub gearcase and ran light grease with water. I've found small amounts of water in different gearcases at lube change and never had problems in the long term. When I find it seals are changed.<br /><br />On the extreme end, due to a defective seal, I had a Merc 20 lower unit lock up at full speed from water in the gears. It screeched like hexx when it locked up...it was only a two week old motor and Merc replaced the unit. Ever since that I always check new motors after the first couple runs to make sure gearcases are tight.<br /><br />A friend of mine hit a rock at high speed and cracked the gearcase (50 Merc) enough to see gears. It was a BIG fracture but didn't affect operation. All the lube came out and water ran in and out freely. He figured it needed a full replacement and ran approx 5 miles back to the dock at high speed. His ob dealer stripped it down and there was no visible damage or wear on the gears. We figured the water rushing in and out kept it cool and lubed without foaming. He swapped gears into a new case and the motor for years after.

 

[rodbolt]

Re: Just how critical is a bit of water in gearcase oil?

and I did the gear case on a friends 95 225 jonnyrude that sat from july of 2002 till july of 2003 with nothing but water in it. lost the upper driveshaft bearings and the lower drive shaft. the boat satfrom july 4th of 2002 till july1st of 2003. the parts that were fully submerged did not get damaged.<br /> had he run it it would not have made a mile.

 

[Tinkerer]

Re: Just how critical is a bit of water in gearcase oil?

Originally posted by llfish:<br /> How do you measure a little bit of water in a gear case full of oil?

That's the hard and maybe the most important part.<br /><br />The first test is sight but the second one is feel. If there's no metal fragments in it then it's assumed to be alright. Even if it might have been milky for the past 5 years.<br /><br />Modern oils contain other things like detergents, rust inhibitors and de-emulsifiers, although I have no idea to what extent these and other things are in marine gearcase oil. It probably varies between brands.<br /><br />For all I know a few drops of water churned up in a gearcase for five minutes has the same effect as churning up a few drops of dishwasher detergent in a Mixmaster bowl for the same time. Looks a lot different and changes the alkalinity and viscosity of the fluid, but it's still pretty effective as the base fluid for most purposes.<br /><br />If a few drops of water produces milky oil, is it that much of a problem? Or does it only get milky if it's, say, 50% water in which case it's lubricant properties are seriously affected and its corrosive capacity a lot more?<br /><br />I don't know. Which is why I started this thread.<br /><br />I'm just wondering if it's one of these things like milky oil in cars in my youth in the '60's when we wouldn't buy a car with milky oil because it was one of those bad signs but a lot of us still ran them for ages in the same condition because we knew what we had to do to keep them going.

 

[Silvertip]

Re: Just how critical is a bit of water in gearcase oil?

Milky oil in a auto crankcase and milky lub in a lower unit are two different problems. Yes -- leakage is the problem. However in a car, the leakage is from the pressurized cooling system which quickly produces a cooling system problem as well as a lubrication problem. A water/oil mix in a car begins to foam since the lubrication system is under 40 - 60 PSI. Camshafts and main/rod bearings deteriorate quickly. Conventional lower units are not pressure lubed so foaming is less likely. Some lower unit lubs take on a milky appearance in five minutes running so unless water actually runs from the drain, my personal feeling is the leak is not significant nor particularly troublesome. My $.02 worth.

 

[Bluefish]

Re: Just how critical is a bit of water in gearcase oil?

You are the only one that can see our feel the oil, if it is a manageable situation you need to decide. You keeping the motor a year a lifetime it is your choice as what to do.

 

[llfish]

Re: Just how critical is a bit of water in gearcase oil?

Upinsmoke, your post is worth a lot more than$.02. Great explanation.

 

[BillP]

Re: Just how critical is a bit of water in gearcase oil?

Let the motor sit overnight and drain the lower unit. Water will drain first, then oil. It's easy to tell how much water is there. A soda bottle capful of water in the lower unit will make the oil look like salad dressing if you drain it immediately after running.

 

[R.Johnson]

Re: Just how critical is a bit of water in gearcase oil?

I have to question The Seagull engine made in Britain, to depend on water, mixing with the oil to lubricate the gearcase. Did that gearcase somehow know when to stop water coming in. Seem's like! one has to get the better of the other. I would like to see the directions that came with that engine. I think we have some confusion here!

 

[Tinkerer]

Re: Just how critical is a bit of water in gearcase oil?

Originally posted by R.Johnson:<br /> I have to question The Seagull engine made in Britain, to depend on water, mixing with the oil to lubricate the gearcase. Did that gearcase somehow know when to stop water coming in. Seem's like! one has to get the better of the other. I would like to see the directions that came with that engine. I think we have some confusion here!

I know it sounds wrong, but it's right. <br /><br />I might have got rid of my British Seagull manuals when I sold mine a couple of years ago. I'll dig around. <br /><br />In the meantime, this bloke is probably the world expert on them and he confirms what I said, and answers your question about the water continually leaking in.<br /><br /> http://www.saving-old-seagulls.co.uk/faq.htm <br /><br />What Oil should be in my gearbox, it looks like coffee sludge? <br /><br />If your gearbox has a mixture of oil and water in a grey/brown slurry, that’s healthy!<br /><br />The gearboxes on most seagulls have no proper oil seals, just a rubber grit seal. The oil will leak out and water get in. They are designed to run on an emulsion of oil and water. However, there comes a time when the water content is too high, so if it is inspected every 10 hours use and found watery, replace it with 140 grade oil. It’s a lot cheaper than the gears.<br /><br />I find horror stories in gearboxes. Full of water or dry, full of dust, rust and salt crystals, or even worse packed with grease…. The grease moves over to let the water in and hey presto, no casehardening, no gears!<br /><br />There is an exception to this apparently. the very early model 102s used a sort of runny grease, thus the grease nipples on the boxes. The earliest ones had proper grease nipples, the ones that a grease gun would clip onto, for these boxes it might be possible to use 250 grade oil and grease mixed. the later oil nipples should use 140, but if it leaks out try 250 grade.

 

[ob]

Re: Just how critical is a bit of water in gearcase oil?

Modern marine lower unit oil contains a level of emullsifiers that will bound up water to a certain extent.Over that extent,the gear oil will reach a pasty consistency which becomes adhered to the inner case walls,away from where it is intended to lubricate.Enough water gets in and you've got yourself an overfilled gearcase full of pasty goo that is not going to afford smoothe gear operation and "will" lead to mechanical breakdown.That's a fact.Seems some of this "don't worry about it" literature is not only poppycock , but assumes that beacuse of antiquated gear case sealing methods on some earlier models that some water is normal and nothing to worry about.IMO , that too is moonshine.The only thing that is 'normal' about it is that bad seals don't hold out water.

 

[R.Johnson]

Re: Just how critical is a bit of water in gearcase oil?

Tinker: That makes a little more sense with a 10 hr. change. Did't the British also make motorcycles with a total loss oil system? This was long ago of course.

 

[umblecumbuz]

Re: Just how critical is a bit of water in gearcase oil?

Quoting Rodbolt:

the boat sat from july 4th of 2002 till july1st of 2003. the parts that were fully submerged did not get damaged.

Seems to me the fact that the motor STOOD is the significant point here. Had the guy run it every day, the humidity which is one of the main causes of metal corrosion in an enclosed space might not have done such damage. It's significant that the metal parts immersed in water/oil emulsion were not so badly affected.<br /><br />The pattern of use of a motor with a gearcase leak obviously makes a difference to its reliability.

 

[Tinkerer]

Re: Just how critical is a bit of water in gearcase oil?

Originally posted by R.Johnson:<br /> Tinker: That makes a little more sense with a 10 hr. change.

They're a great little motor. Couldn't kill it with a cannon. Beautifully simple. Can haul it into the boat and dismantle it completely with a screwdriver and shifter if you had to. Low speed but big thrust. Yachties liked them because a 4HP could push a 23' foot along quite well.<br /><br />

Originally posted by R.Johnson:<br /> Did't the British also make motorcycles with a total loss oil system? This was long ago of course.

Apparently it was used fairly widely in the early days.<br /><br /> http://www.dansmc.com/4_stroke_oilpump.htm <br /><br />Lastly we have Total Loss lubrication. This was used on motorcycles back in the early 1900s. Early motorcycle engines had plain babbet bearings or roller and needle bearings or a combination of both. Oil, oilpumps, babbet and everything else were all kind of new back then and not as good of quality as we have today. Because of this, high output engines used roller and needle bearings. The engines had hand pumps on their oil tanks. When you started the engine you gave 'er a shot of oil. Every so many miles you would give the engine another stroke of the pump. The engine used up the oil and got more clean, fresh oil to the bearings with each stroke of the pump. The engines had sumps and these where filled with oil to start with and splash lubrication took care of the rest of the engine. This gave lots of clean, fresh oil always going through the engine. Sometimes the engines had a Drip feed Lubricator, in addition to the hand pump. One pump of oil every eight to ten miles at 20 MPH was deemed sufficient. At 30 MPH you needed one pump every five or six miles. The Drip Feed should be set at 8 drops per minute, just in case you wanted to know. I don't think you will run into too many of these machines !

 

[BillP]

Re: Just how critical is a bit of water in gearcase oil?

Originally posted by ob:<br /> Modern marine lower unit oil contains a level of emullsifiers that will bound up water to a certain extent.Over that extent,the gear oil will reach a pasty consistency which becomes adhered to the inner case walls,away from where it is intended to lubricate.Enough water gets in and you've got yourself an overfilled gearcase full of pasty goo that is not going to afford smoothe gear operation and "will" lead to mechanical breakdown.That's a fact.Seems some of this "don't worry about it" literature is not only poppycock , but assumes that beacuse of antiquated gear case sealing methods on some earlier models that some water is normal and nothing to worry about.IMO , that too is moonshine.The only thing that is 'normal' about it is that bad seals don't hold out water.

OB,<br />Poppycock...Moonshine? Let me make it clear so your asumptions of my postings are accurate. I'm not saying water in the unit is normal for today's motors or that is is ok to run long term with water in the gearcase...however, it was normal and worked in older motors without trashing the gears. They also let the water run out after every outing and the lube ran out with it. If you wanted the lower unit to last you had to check lube every day. If maintained this way the gears lasted a long time. <br /><br />If "paste" was such a problem it seems I would have seen it a least in one motor in 40+ yrs of ob boating. I've seen/had plenty of gearcases with water in them and resealed many motors because of it. I even had a V4 75 johnson that only got water in it if I ran it in reverse at high speeds. Never had a lower unit failure or premature death on any case that was found to have run with a "little" water in it either.<br /><br />Should someone freak out if they see a "little" (capful)water in the gearcase? NO. Should they park the boat and reseal? YES.