gear oil water saturation

[vinnie1234]

Hi there. I have a 400 series outdrive, I am new to boats and so I am wondering if what I observe is normal or not. In my upper and lower units, I believe I have a small amount of water getting in. I have pressure tested the upper and lower units to 10 psi (and they lose pressure very slowly, so I am thinking the seals are okay) - anyway after a few runs I pulled the drain plug to see the condition of the oil and it is slightly milky. no water comes out, so I think that whatever moisture is there is being held in solution in the gear oil. Obviously it needs to be changed when it gets right nasty, but my question: is it normal to see perfect clear gear oil, or do you get a bit of water in there no matter what? I don't want to go ripping it all apart for a small amount of water intrusion that may be considered normal. thanks!

 

[southkogs]

Both of my gear cases have been pretty water tight (surprisingly enough), though from time to time you may get some water invasion. So, a short answer to your questions is that it should not be normal to consistently see evidence of water in the gear case.

If you're seeing consistent evidence of water in the upper gear case, I would start working the problem now so to avoid bigger issues later. Try some simple things: I dunno' what year your 400 is, but check the rings on the top cap and the lube fill and things of that nature. One of them might be letting some water in. Probably not a panic point right now, but work on it as you can as a preemptive strike.

 

[vinnie1234]

Thanks southkogs. I have read about horror stories with the gearcases seizing right up because of water in the gearcase, however if I read between the lines, it would seem like this is more of an issue related to corrosion causing bearing damage and heat from lack of film strength than it is of massive gear failure. People not keeping up on the boat y'know. I can't imagine that with an unvented gearcase (fully submersed) you could get by with no water intrusion for long.

 

[Scott Danforth]

once properly sealed, my 400 was surprisingly water and oil tight.

besides the points that 'kogs mentioned, another place to check is the water pump. The water pump housing is also the bottom of the upper gear box. I had a small hole in mine from dirt and debris in the impeller housing that effectively cut a nice groove thru the aluminum housing. from there it made an effective pump to remove the gear oil from the upper and replace it with water.

and yes, it seized up tight, about 1/2 mile from the launch

 

[vinnie1234]

Wow. That sucks. I actually changed the pump out because the housing was cracked. I used a healthy amount of gasket sealer wherever I could, so I think it is probably okay. I have also been watching the exhaust of the boat for signs of oil leakage. When in the water, I am constantly looking for the telltale rainbow in the lake and in the driveway I have inspected the puddle on the ground, and grabbed handfuls of water a few times to see that it is clean and free of oil.
I am being ultra picky about this because I want the boating experience for the family to be fee of trouble so I can get everyone pumped about boating. If I miss something and end up having to paddle for 3 hours, at this stage in the game it will likely ruin it for everyone and I will just end up selling it.

Anyway, as I write this, I have to wonder if I could rig up a pressure guage to the upper fill plug and measure for an increase in pressure while the engine is running? That might tell me if the water pump was trying to insert water into my upper?

 

[bruceb58]

I have pressure tested the upper and lower units to 10 psi (and they lose pressure very slowly, so I am thinking the seals are okay)

They should hold 10 PSI. They don't sound OK to me at all.

 

[vinnie1234]

Thanks Bruce. I am guessing that you have pressure tested these yourself and found them to hold that much air? I only have what I have read to go on as I have never worked on boats. I have read elsewhere on the internet that you will have a slow leakdown over a couple of minutes, so I thought it may be okay. I have also had the units pressurized with soapy water on them and found no bubbles. Part of me thinks that my pressure tester is the source of the leak - either in the tube or at the drain plug. Here is what I did:

To pressure test I made a tester using the gear oil filler attachment with a valve stem attached to it. Sealed with electrical tape. (good stuff huh?)
I connected a regulated air feed at 10psi to the valve stem so there was a constant air supply to the gearcase. Listened at the openings for air and it was quiet - and used soap and water anywhere I could splash it and could see no bubbles. The only way I could really check air flow through was to drop some gear oil in the tube and watch it move with air flow. I would see a bubble pass about every 5 or 6 seconds. I also took a tire pressure guage and read the pressure through the valve stem that way, and it seemed to hold, but it is hard to account for pressure loss experienced while connecting the guage.

The comment I made about leaking very slowly comes from my observation of air passing from the air supply down the tube. I would think that if there were a substantial pressure leak, I would be able to observe a decent quantity of oil coming out somewhere. Even leaving it on pressure for a while, there are no observable leaks....... Any better ideas on how I can/should test this?

 

[bruceb58]

We had a brand new OMC back in 1975 that leaked from day one. We took it to the dealer and they changed all the seals and showed us the pressure test with it holding pressure.

I would make a setup that had a gauge already connected in the setup. Just takes some tees and you can make one.

By the way, water can get in way easier than oil getting out. We were getting water in our gear oil without having a leak.

 

[vinnie1234]

It sounds like this is a little trickier than I figured at first glance. I think you are right. It may be a while for me to get some time, but I am thinking I will make something that will also take a plastic washer to ensure a seal at the drain plug. Maybe I can use some brake line and fittings to hook up to the t's and go from there.

If you want a laugh..... when I first got this thing and pulled the water pump out - there was a ton of water in the upper case. (the crack in the water pump housing was 3" long and 1/4 inch wide). Not thinking about how they were put together I figured - I will just hook up some pressure to the drain plug and see if I can find the leak. So, I did just that. Got it up to about 5 psi and " BWAM" The damn gear housing fired out of there like a cannon. Scared the hell out of me. Luckily I had a nice sized pile of rags on the floor because I had spilled some gear oil.....that saved me from damaging the housing. I could have had my freaking head up there looking for a leak!
Anyway, I didn't realize that the water pump bolts held that in there.

The point to this story, is I am a little nervous putting pressure to this stuff because I don't know what it will take. 15? 20? 50? I thank you for the tips, and will use 15 as a threshold. Try not to flog me too badly for taking this apart and not changing the seals. They looked fine to the eyes of a car guy.

 

[bruceb58]

Look at the first two links

http://forums.iboats.com/forum/engi...ines-outdrives/481978-home-made-special-tools

You are testing with all gear oil drained right?

 

[vinnie1234]

Great links Bruce. Thanks. An yes, I was testing with oil drained. As we discuss this I was thinking about filling the gearcase and then pressure testing to look for a drip, but I think the gear oil is likely too viscous for that. Parts washing fluid crossed my mind.....Maybe not a good idea. I'll have to ponder that one. But in any case, a good quality tool, (other than a valve stem electrical tape and a tire guage) will likely do the trick.

I will make something up and let you know the results.

Before I do this... I will just confirm that YOU think slightly milky oil is not normal and I have a leak - and that I need to find it .. Right?

Not to say that I would rather be boating. But I would rather be boating.

 

[bruceb58]

You need to find it. When we had our issue, we were draining and refilling every time we went out before we finally got it fixed in the fall.

 

[vinnie1234]

So, (just trying to understand) you knew you had a water leak before it seized, and were draining and refilling every time and it still broke? OR - once it seized, it freed up after cooling, you changed the oil and it was fine to use until the fall when you had it serviced? I am only asking because I find it hard to fathom that with a fresh change 1 run would cause a seizure. Any yes, I know that I used fathom and water in that sentence. I am thinking about running it and just changing the oil frequently, as I work out the other bugs......

 

[bruceb58]

It never seized.

 

[vinnie1234]

Hi Bruce. sorry about that. Scott Danforth had the seizure. I got a bit confused. :facepalm:

 

[southkogs]

Vinnie - it's not that it'll seize for sure with a little water intrusion. It's that the probability is a lot higher with a little water intrusion. You can keep using the unit if you keep checking the lube and changing it as needed ... but you ultimately need to stop the intrusion.

I had a sterndrive that I picked up for parts that I tried out the upper with. Put it in the water one time and it came back filled with milky lube. Drained everything out and put new lube in it and it still works fine, but the minute I submerge the thing it's going to fill up again. Eventually it'll seize up if I don't fix the leaks. (<== that upper is not on the boat currently)

 

[vinnie1234]

So I changed the gear oil in the upper and lower gearcase the other day. Before I went to take the boat out yesterday, I figured I would pull off the top of the housing and have a look at the steering mechanism, so I brought it into the shop and drained the oil from the upper. @ things to make note of. First of all, with the fill plug in, I only get the odd drip of oil here and there, which tells me that the seal is pretty decent, if not perfect. When I removed the fill plug to get the oil out, it looked exactly the same as it did after the last time I had it in the water. A very slight creamy colour. Well, the steering mechanism is just fine, and I decided that perhaps there was a seal problem with the water pump. perhaps there was some moisture getting in there that way. So I pulled the water pump. Nope. nice and tight.
I have to wonder if this isn't normal. It does look different than the gear oil that we pull out od a differential, so I am fairly sure it looks like water intrusion, but without having it in the water - and with the water pump bone dry and sealed up tight I am thinking "what the hell??"
Just thought I would update this and let you know if there actually is a leak or not.

I am going to leave the current gear oil in there and keep checking it. As soon as I get a little rush of water out the drainplug I will change it, but if I don't get that little rush of water, I think I will call it sealed!
Cheers,