1990 Yamaha 150hp oil leak

[bdeskins]

I noticed some oil leaking from a drainage whole on the lower unit.  The whole is located about 3-4" below a screw labeld OIL LEVEL.  Is this leakage normal?  It was not an abundance of oil, but I had never noticed it before.

The boat is on the trailer and I had the engine resting at an angle on the transom.  I have now lowered it so that it is almost down as much as it is in the water.  What position should I leave the engine in when on the trailer and not being towed AND would that have anything to do with the leak from the lower unit?

Thanks for your help.

[John Jones]

I leave mine as straight up and down as possible.

It depends on what oil it is.  If it's black, it's probably just unburned 2-stroke oil from the exhaust, especially if you run it for any length of time on the hose.  The motor doesn't get hot enough to burn off all the oil in the fuel.  If it's brown to yellow, it could be from the lower unit.  The lower unit should be checked for oil level and condition several times per year and changed anually, if not more often.  If it's black oil from the lower unit, it should have been changed 3 years ago.

[RickK]

When you run the motor on the muffs, does water spray out that hole?  I think mine ('91 250) has that same hole and water does shoot out of it.  JJ probably has it right but since I'm no mechanic, I'll defer to someone that is.  Seems that some seal is not right there - I don't see oil coming out of mine there.

[bdeskins]

Thanks for the help!  The oil looks like unburned 2 stroke, pretty clean.  I will check the lower unit level and condition.  The motor runs and idles great.  There is a little smoke when I first start it, but other than that not much.

[GoneFission]

The oil level hole on the lower unit that is marked "oil level" is the upper hole for the gearcase.  I should not have oil running out of it.  If it does, you probably have water in the gearcase.  

You should drain the gearcase by taking out the plug at the "oil level" point, then put a pan under the lower unit (gearcase) to catch the oil, and drain the lower unit by removing the drain plug on the bottom.  If you are lucky, you will not have much water in there.  

Check the drain plugs carefully - there may be a rubber o-ring on the plug that is damaged.  If not, put some teflon tape on the plug before replacing it.  You fill the lower unit by squirting marine gear lube (that's why the tubes are shaped that way) from the bottom hole until it comes our the top hole (that's why it's labeled "oil level").  Then quickly put the plug back in the bottom hole and then replace the plug in in the top hole.  If it's all sealed up good, you won't have leakage in the future.  

See ya on the water!

[bdeskins]

Thanks for the posts concering the leak. I though I would include a pic to show wher ehte leak is.  The OIL FILL LEVEL seems to be fine, and the OIL DRAIN HOLE seems to be fine as well.  The leak is from a manufactured hole in between.  I had some oil leaking in under the cowling and thought mayeb it was making it all the down to the lower unit, but I am no sure if that is even possible.

[JimCt]

Only two sources of oil: fuel mix and the lower unit.  If it's from the fuel what you are seeing is unburned oil.  Not a concern.

My uneducated guess is the hole's an exhaust weep-hole put there to prevent unburned exhaust oil from accumulating in the leg.

[bdeskins]

thanks Jim, I like the sound of that answer!

I have added a few more pics under bdeskins in the members gallery.

I now have the gas tank cover off.  I was thining about reinforcing with a little more resin and cloth (because it is a little soft when standing on it), but once I got it off, I am not sure that that is a good idea.  The whole piece seems to be made to flex.  It was not a soft spot in the one particular area that I stand at the helm, but the whole thing had similar rigidity.  Do you have any experience with this?

[JimCt]

How much weight are you putting on the panel when you see it flex?  Big difference if you weigh 120# or 285#...

[bdeskins]

I weigh about 170

[JimCt]

Panel should be fairly (relative term) stiff under your weight.  If it's uncomfortably springy the wood core in the panel may be starting to deteriorate from moisture intrusion. It is easily replaced by grinding off the glass matting from the underside of the panel, removing the old plywood and glassing in a new core.