Pontoon Boat & Deck Boat Forum

Long story short ..

First time doing maintenance on my outboard. I was doing my 20 hour service and changing my lower unit oil. I misread the manual (or didn't read it good enough) and filled the lower unit from the upper "check" hole with the drain hole plugged. I was using a pump and the pressure got too great and oil out leaked from the water intakes and a little out the back from the prop. Great

I realized now what I did was bad. My next course of action is to drain the lower unit again and do a pressure test on it. Manual says 14 psi for 5 minutes is what it should hold. If this test comes out successful, is there anything else I need to check? I know if it fails that I need to replace some seals and read better next time.

Thanks again

WOW

Be sure and fill from bottom

OOps! hope all is well. Yep that's a lot of hydro pressure on seals not designed for it.

A thought.............fill with oil and put it in the water for a while then check for water in the oil. Worse scenario is then you have to change seals.

RcgTexas wrote:OOps! hope all is well. Yep that's a lot of hydro pressure on seals not designed for it.

A thought.............fill with oil and put it in the water for a while then check for water in the oil. Worse scenario is then you have to change seals.

That sounds like a good idea. I'll fill it with oil then submerge the lower half in a big container of water and wait a bit. If no water makes it in, I guess all should be good.

Lower units are best tested by a qualified mechanic--vacuum and pressure tested--from time to time. The penalty for missing a leaking seal could cost you a whole lower unit. New lower units are beyond expensive.

I ignored my lower unit on a Yamaha 115 hp 2 stroke, and it was toast. I had to buy a whole new boat--after 27 years' use on the old one.

Chances are your engine's fine, however.

creel wrote:That sounds like a good idea.

Sorry, but putting it the water to test for a leak is an incredibly BAD idea.

Do a pressure test on it.

Fill from the bottom. Get a service manual and read it next time you want to do maintenance on your engine

I haven't changed the lower unit oil on my boat myself, so I haven't researched the issue. Why do they require that you fill from the bottom? Seems counter intuitive.

C_M_25 wrote:I haven't changed the lower unit oil on my boat myself, so I haven't researched the issue. Why do they require that you fill from the bottom? Seems counter intuitive.

The top hole allows air to escape while pumping oil from the bottom. This ensures the lower unit is full when oil starts to leak from the top hole.

If you don't fill from the bottom , you will get air pockets so the drive isn't full and you will wipe out your gears.

babock wrote:

creel wrote:That sounds like a good idea.

Sorry, but putting it the water to test for a leak is an incredibly BAD idea.

Do a pressure test on it.

Fill from the bottom. Get a service manual and read it next time you want to do maintenance on your engine

The worse thing that can happen is it leaks. then replace the oil and find the leaking seal. if it doesn't leak water, there is no incredible problem.

I'm not saying run it for a season just see if it leaks and then keep an eye on it. Any water will be at the bottom and will show itself when the plug is removed.

If you drain the oil and it is coffe brown color you have water getting in there and mixing with the oil. When you buy gear oil buy the pump that screws on the lower unit drain and when you pump the oil and it comes out the top hole screw the cap back on before removing the pump and then quickly screw the bottom as soon as you pull out the pump.

RcgTexas wrote:The worse thing that can happen is it leaks.

No...worst thing that happens is that it leaks and you now have water in your drive that mixes with the oil and can cause rust in your bearings. Actually, I can think of an even worse scenario...the seals are so blown that the gear oil leaks profusely and the gear oil drops so bad that the gears are wiped out. I know one thing...I would NEVER take that chance with my boat or give that advice to someone else.

You pressure test first to see if there is a leak.

Always makes me wonder why people don't fix things right the first time!

Wow talk about some dooms dayers.... First off he does not know that the seals are "blown" as just because they were overwhelmed does not mean they are ruined. As to getting a little water in the oil believe me it is not the end of the world and it will not wipe out your gears unless all oil has been displaced by the water. For years I watched my father nurse a foot that had an unrepairable leak. We used that motor without reservation simply by checking the lower drain for signs of water and would replace the oil after every couple of weekends worth of use when it showed up milky. Having spent nearest to 30 years working in the engine room on boat and ships I've dealt with water in oil lots of times and its never been a death sentence once known and watched. If I didn't have the means of pressure testing the foot I'd simply fill to correct level, wash the outside down good with Dawn to break up any oil left on the foot surface. Go put the boat in the water or find a barrel to test with. Watch for oil at the dock if none shows start up and let idle in gear and continue to check for oil to come to the surface. Go from there....

It takes an hour to do the job right!

Pressure test it and be done with it.

Reminds me of the quote " There's never time to do it right the first time but always time to do it over the next".

And yes, having water in your drive is not a good thing no matter how long it's in there. I have taken drives apart where just a little moisture was in there and there was a coating of rust on everything.

teecro wrote:Wow talk about some dooms dayers.... First off he does not know that the seals are "blown" as just because they were overwhelmed does not mean they are ruined. As to getting a little water in the oil believe me it is not the end of the world and it will not wipe out your gears unless all oil has been displaced by the water. For years I watched my father nurse a foot that had an unrepairable leak. We used that motor without reservation simply by checking the lower drain for signs of water and would replace the oil after every couple of weekends worth of use when it showed up milky. Having spent nearest to 30 years working in the engine room on boat and ships I've dealt with water in oil lots of times and its never been a death sentence once known and watched. If I didn't have the means of pressure testing the foot I'd simply fill to correct level, wash the outside down good with Dawn to break up any oil left on the foot surface. Go put the boat in the water or find a barrel to test with. Watch for oil at the dock if none shows start up and let idle in gear and continue to check for oil to come to the surface. Go from there....

I agree.

I've had coffee cream colored oil draining out for years - and it still works just fine. The key is to change it often - which is dirt cheap and easy. I also fill it from the top using a hose jammed onto the tapered spout of the gear lube bottle, and a smaller "step down" hose inline and then inserted in the check hole. It's not real fast this way, since air will slowly bubble out between the inserted hose and check hole allowing it to fill to the top. I just hang the FULL bottle upside down, monitor it and let it take it's time while I do other maintenance. Kind of like an IV drip in a hospital. If you want it to fill faster you can always squeeze the bottle - takes maybe 5 minutes this way. I may get motivated one day and repair the little booger, but it's a low priority. It's of course VERY important to change out the oil BEFORE it's stored for any length of time since rust never sleeps. I do it at the same time I drain the carbs, fuel pump, lines and fuel filter. Nuttin' to it.